\input texinfo @c -*-texinfo-*-
@c Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998,
-@c 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+@c 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
@c Free Software Foundation, Inc.
@c
@c %**start of header
@finalout
@syncodeindex ky cp
+@syncodeindex tp cp
@c readline appendices use @vindex, @findex and @ftable,
@c annotate.texi and gdbmi use @findex.
@copying
Copyright @copyright{} 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
-1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
@end ifset
Version @value{GDBVN}.
-Copyright (C) 1988-2009 Free Software Foundation, Inc.
+Copyright (C) 1988-2010 Free Software Foundation, Inc.
This edition of the GDB manual is dedicated to the memory of Fred
Fish. Fred was a long-standing contributor to GDB and to Free
* Running:: Running programs under @value{GDBN}
* Stopping:: Stopping and continuing
* Reverse Execution:: Running programs backward
+* Process Record and Replay:: Recording inferior's execution and replaying it
* Stack:: Examining the stack
* Source:: Examining source files
* Data:: Examining data
+* Optimized Code:: Debugging optimized code
* Macros:: Preprocessor Macros
* Tracepoints:: Debugging remote targets non-intrusively
* Overlays:: Debugging programs that use overlays
* Emacs:: Using @value{GDBN} under @sc{gnu} Emacs
* GDB/MI:: @value{GDBN}'s Machine Interface.
* Annotations:: @value{GDBN}'s annotation interface.
+* JIT Interface:: Using the JIT debugging interface.
* GDB Bugs:: Reporting bugs in @value{GDBN}
@value{GDBN}
* Operating System Information:: Getting additional information from
the operating system
+* Trace File Format:: GDB trace file format
* Copying:: GNU General Public License says
how you can copy and share GDB
* GNU Free Documentation License:: The license for this documentation
who have worked on the Xtensa port of @value{GDBN} in the past include
Steve Tjiang, John Newlin, and Scott Foehner.
+Michael Eager and staff of Xilinx, Inc., contributed support for the
+Xilinx MicroBlaze architecture.
+
@node Sample Session
@chapter A Sample @value{GDBN} Session
@itemx -x @var{file}
@cindex @code{--command}
@cindex @code{-x}
-Execute @value{GDBN} commands from file @var{file}. @xref{Command
-Files,, Command files}.
+Execute commands from file @var{file}. The contents of this file is
+evaluated exactly as the @code{source} command would.
+@xref{Command Files,, Command files}.
@item -eval-command @var{command}
@itemx -ex @var{command}
@item apropos @var{args}
The @code{apropos} command searches through all of the @value{GDBN}
commands, and their documentation, for the regular expression specified in
-@var{args}. It prints out all matches found. For example:
+@var{args}. It prints out all matches found. For example:
@smallexample
apropos reload
* Attach:: Debugging an already-running process
* Kill Process:: Killing the child process
-* Inferiors:: Debugging multiple inferiors
+* Inferiors and Programs:: Debugging multiple inferiors and programs
* Threads:: Debugging programs with multiple threads
-* Processes:: Debugging programs with multiple processes
+* Forks:: Debugging forks
* Checkpoint/Restart:: Setting a @emph{bookmark} to return to later
@end menu
the compiler.
Programs that are to be shipped to your customers are compiled with
-optimizations, using the @samp{-O} compiler option. However, many
+optimizations, using the @samp{-O} compiler option. However, some
compilers are unable to handle the @samp{-g} and @samp{-O} options
together. Using those compilers, you cannot generate optimized
executables containing debugging information.
without @samp{-O}, making it possible to debug optimized code. We
recommend that you @emph{always} use @samp{-g} whenever you compile a
program. You may think your program is correct, but there is no sense
-in pushing your luck.
-
-@cindex optimized code, debugging
-@cindex debugging optimized code
-When you debug a program compiled with @samp{-g -O}, remember that the
-optimizer is rearranging your code; the debugger shows you what is
-really there. Do not be too surprised when the execution path does not
-exactly match your source file! An extreme example: if you define a
-variable, but never use it, @value{GDBN} never sees that
-variable---because the compiler optimizes it out of existence.
-
-Some things do not work as well with @samp{-g -O} as with just
-@samp{-g}, particularly on machines with instruction scheduling. If in
-doubt, recompile with @samp{-g} alone, and if this fixes the problem,
-please report it to us as a bug (including a test case!).
-@xref{Variables}, for more information about debugging optimized code.
+in pushing your luck. For more information, see @ref{Optimized Code}.
Older versions of the @sc{gnu} C compiler permitted a variant option
@w{@samp{-gg}} for debugging information. @value{GDBN} no longer supports this
reads the symbol table again (while trying to preserve your current
breakpoint settings).
-@node Inferiors
-@section Debugging Multiple Inferiors
+@node Inferiors and Programs
+@section Debugging Multiple Inferiors and Programs
-Some @value{GDBN} targets are able to run multiple processes created
-from a single executable. This can happen, for instance, with an
-embedded system reporting back several processes via the remote
-protocol.
+@value{GDBN} lets you run and debug multiple programs in a single
+session. In addition, @value{GDBN} on some systems may let you run
+several programs simultaneously (otherwise you have to exit from one
+before starting another). In the most general case, you can have
+multiple threads of execution in each of multiple processes, launched
+from multiple executables.
@cindex inferior
@value{GDBN} represents the state of each program execution with an
object called an @dfn{inferior}. An inferior typically corresponds to
a process, but is more general and applies also to targets that do not
have processes. Inferiors may be created before a process runs, and
-may (in future) be retained after a process exits. Each run of an
-executable creates a new inferior, as does each attachment to an
-existing process. Inferiors have unique identifiers that are
-different from process ids, and may optionally be named as well.
-Usually each inferior will also have its own distinct address space,
-although some embedded targets may have several inferiors running in
-different parts of a single space.
+may be retained after a process exits. Inferiors have unique
+identifiers that are different from process ids. Usually each
+inferior will also have its own distinct address space, although some
+embedded targets may have several inferiors running in different parts
+of a single address space. Each inferior may in turn have multiple
+threads running in it.
-Each inferior may in turn have multiple threads running in it.
-
-To find out what inferiors exist at any moment, use @code{info inferiors}:
+To find out what inferiors exist at any moment, use @w{@code{info
+inferiors}}:
@table @code
@kindex info inferiors
@item info inferiors
Print a list of all inferiors currently being managed by @value{GDBN}.
+@value{GDBN} displays for each inferior (in this order):
+
+@enumerate
+@item
+the inferior number assigned by @value{GDBN}
+
+@item
+the target system's inferior identifier
+
+@item
+the name of the executable the inferior is running.
+
+@end enumerate
+
+@noindent
+An asterisk @samp{*} preceding the @value{GDBN} inferior number
+indicates the current inferior.
+
+For example,
+@end table
+@c end table here to get a little more width for example
+
+@smallexample
+(@value{GDBP}) info inferiors
+ Num Description Executable
+ 2 process 2307 hello
+* 1 process 3401 goodbye
+@end smallexample
+
+To switch focus between inferiors, use the @code{inferior} command:
+
+@table @code
+@kindex inferior @var{infno}
+@item inferior @var{infno}
+Make inferior number @var{infno} the current inferior. The argument
+@var{infno} is the inferior number assigned by @value{GDBN}, as shown
+in the first field of the @samp{info inferiors} display.
+@end table
+
+
+You can get multiple executables into a debugging session via the
+@code{add-inferior} and @w{@code{clone-inferior}} commands. On some
+systems @value{GDBN} can add inferiors to the debug session
+automatically by following calls to @code{fork} and @code{exec}. To
+remove inferiors from the debugging session use the
+@w{@code{remove-inferior}} command.
+
+@table @code
+@kindex add-inferior
+@item add-inferior [ -copies @var{n} ] [ -exec @var{executable} ]
+Adds @var{n} inferiors to be run using @var{executable} as the
+executable. @var{n} defaults to 1. If no executable is specified,
+the inferiors begins empty, with no program. You can still assign or
+change the program assigned to the inferior at any time by using the
+@code{file} command with the executable name as its argument.
+
+@kindex clone-inferior
+@item clone-inferior [ -copies @var{n} ] [ @var{infno} ]
+Adds @var{n} inferiors ready to execute the same program as inferior
+@var{infno}. @var{n} defaults to 1. @var{infno} defaults to the
+number of the current inferior. This is a convenient command when you
+want to run another instance of the inferior you are debugging.
+
+@smallexample
+(@value{GDBP}) info inferiors
+ Num Description Executable
+* 1 process 29964 helloworld
+(@value{GDBP}) clone-inferior
+Added inferior 2.
+1 inferiors added.
+(@value{GDBP}) info inferiors
+ Num Description Executable
+ 2 <null> helloworld
+* 1 process 29964 helloworld
+@end smallexample
+
+You can now simply switch focus to inferior 2 and run it.
+
+@kindex remove-inferior
+@item remove-inferior @var{infno}
+Removes the inferior @var{infno}. It is not possible to remove an
+inferior that is running with this command. For those, use the
+@code{kill} or @code{detach} command first.
+
+@end table
+
+To quit debugging one of the running inferiors that is not the current
+inferior, you can either detach from it by using the @w{@code{detach
+inferior}} command (allowing it to run independently), or kill it
+using the @w{@code{kill inferior}} command:
+
+@table @code
+@kindex detach inferior @var{infno}
+@item detach inferior @var{infno}
+Detach from the inferior identified by @value{GDBN} inferior number
+@var{infno}, and remove it from the inferior list.
+
+@kindex kill inferior @var{infno}
+@item kill inferior @var{infno}
+Kill the inferior identified by @value{GDBN} inferior number
+@var{infno}, and remove it from the inferior list.
+@end table
+
+After the successful completion of a command such as @code{detach},
+@code{detach inferior}, @code{kill} or @code{kill inferior}, or after
+a normal process exit, the inferior is still valid and listed with
+@code{info inferiors}, ready to be restarted.
+
+
+To be notified when inferiors are started or exit under @value{GDBN}'s
+control use @w{@code{set print inferior-events}}:
+
+@table @code
@kindex set print inferior-events
@cindex print messages on inferior start and exit
@item set print inferior-events
inferiors have started, exited or have been detached.
@end table
+Many commands will work the same with multiple programs as with a
+single program: e.g., @code{print myglobal} will simply display the
+value of @code{myglobal} in the current inferior.
+
+
+Occasionaly, when debugging @value{GDBN} itself, it may be useful to
+get more info about the relationship of inferiors, programs, address
+spaces in a debug session. You can do that with the @w{@code{maint
+info program-spaces}} command.
+
+@table @code
+@kindex maint info program-spaces
+@item maint info program-spaces
+Print a list of all program spaces currently being managed by
+@value{GDBN}.
+
+@value{GDBN} displays for each program space (in this order):
+
+@enumerate
+@item
+the program space number assigned by @value{GDBN}
+
+@item
+the name of the executable loaded into the program space, with e.g.,
+the @code{file} command.
+
+@end enumerate
+
+@noindent
+An asterisk @samp{*} preceding the @value{GDBN} program space number
+indicates the current program space.
+
+In addition, below each program space line, @value{GDBN} prints extra
+information that isn't suitable to display in tabular form. For
+example, the list of inferiors bound to the program space.
+
+@smallexample
+(@value{GDBP}) maint info program-spaces
+ Id Executable
+ 2 goodbye
+ Bound inferiors: ID 1 (process 21561)
+* 1 hello
+@end smallexample
+
+Here we can see that no inferior is running the program @code{hello},
+while @code{process 21561} is running the program @code{goodbye}. On
+some targets, it is possible that multiple inferiors are bound to the
+same program space. The most common example is that of debugging both
+the parent and child processes of a @code{vfork} call. For example,
+
+@smallexample
+(@value{GDBP}) maint info program-spaces
+ Id Executable
+* 1 vfork-test
+ Bound inferiors: ID 2 (process 18050), ID 1 (process 18045)
+@end smallexample
+
+Here, both inferior 2 and inferior 1 are running in the same program
+space as a result of inferior 1 having executed a @code{vfork} call.
+@end table
+
@node Threads
@section Debugging Programs with Multiple Threads
@item thread-specific breakpoints
@item @samp{set print thread-events}, which controls printing of
messages on thread start and exit.
+@item @samp{set libthread-db-search-path @var{path}}, which lets
+the user specify which @code{libthread_db} to use if the default choice
+isn't compatible with the program.
@end itemize
@quotation
@xref{Set Watchpoints,,Setting Watchpoints}, for information about
watchpoints in programs with multiple threads.
-@node Processes
-@section Debugging Programs with Multiple Processes
+@table @code
+@kindex set libthread-db-search-path
+@cindex search path for @code{libthread_db}
+@item set libthread-db-search-path @r{[}@var{path}@r{]}
+If this variable is set, @var{path} is a colon-separated list of
+directories @value{GDBN} will use to search for @code{libthread_db}.
+If you omit @var{path}, @samp{libthread-db-search-path} will be reset to
+an empty list.
+
+On @sc{gnu}/Linux and Solaris systems, @value{GDBN} uses a ``helper''
+@code{libthread_db} library to obtain information about threads in the
+inferior process. @value{GDBN} will use @samp{libthread-db-search-path}
+to find @code{libthread_db}. If that fails, @value{GDBN} will continue
+with default system shared library directories, and finally the directory
+from which @code{libpthread} was loaded in the inferior process.
+
+For any @code{libthread_db} library @value{GDBN} finds in above directories,
+@value{GDBN} attempts to initialize it with the current inferior process.
+If this initialization fails (which could happen because of a version
+mismatch between @code{libthread_db} and @code{libpthread}), @value{GDBN}
+will unload @code{libthread_db}, and continue with the next directory.
+If none of @code{libthread_db} libraries initialize successfully,
+@value{GDBN} will issue a warning and thread debugging will be disabled.
+
+Setting @code{libthread-db-search-path} is currently implemented
+only on some platforms.
+
+@kindex show libthread-db-search-path
+@item show libthread-db-search-path
+Display current libthread_db search path.
+@end table
+
+@node Forks
+@section Debugging Forks
@cindex fork, debugging programs which call
@cindex multiple processes
Show whether detach-on-fork mode is on/off.
@end table
-If you choose to set @samp{detach-on-fork} mode off, then
-@value{GDBN} will retain control of all forked processes (including
-nested forks). You can list the forked processes under the control of
-@value{GDBN} by using the @w{@code{info forks}} command, and switch
-from one fork to another by using the @w{@code{fork}} command.
+If you choose to set @samp{detach-on-fork} mode off, then @value{GDBN}
+will retain control of all forked processes (including nested forks).
+You can list the forked processes under the control of @value{GDBN} by
+using the @w{@code{info inferiors}} command, and switch from one fork
+to another by using the @code{inferior} command (@pxref{Inferiors and
+Programs, ,Debugging Multiple Inferiors and Programs}).
-@table @code
-@kindex info forks
-@item info forks
-Print a list of all forked processes under the control of @value{GDBN}.
-The listing will include a fork id, a process id, and the current
-position (program counter) of the process.
+To quit debugging one of the forked processes, you can either detach
+from it by using the @w{@code{detach inferior}} command (allowing it
+to run independently), or kill it using the @w{@code{kill inferior}}
+command. @xref{Inferiors and Programs, ,Debugging Multiple Inferiors
+and Programs}.
-@kindex fork @var{fork-id}
-@item fork @var{fork-id}
-Make fork number @var{fork-id} the current process. The argument
-@var{fork-id} is the internal fork number assigned by @value{GDBN},
-as shown in the first field of the @samp{info forks} display.
+If you ask to debug a child process and a @code{vfork} is followed by an
+@code{exec}, @value{GDBN} executes the new target up to the first
+breakpoint in the new target. If you have a breakpoint set on
+@code{main} in your original program, the breakpoint will also be set on
+the child process's @code{main}.
-@kindex process @var{process-id}
-@item process @var{process-id}
-Make process number @var{process-id} the current process. The
-argument @var{process-id} must be one that is listed in the output of
-@samp{info forks}.
+On some systems, when a child process is spawned by @code{vfork}, you
+cannot debug the child or parent until an @code{exec} call completes.
-@end table
+If you issue a @code{run} command to @value{GDBN} after an @code{exec}
+call executes, the new target restarts. To restart the parent
+process, use the @code{file} command with the parent executable name
+as its argument. By default, after an @code{exec} call executes,
+@value{GDBN} discards the symbols of the previous executable image.
+You can change this behaviour with the @w{@code{set follow-exec-mode}}
+command.
-To quit debugging one of the forked processes, you can either detach
-from it by using the @w{@code{detach fork}} command (allowing it to
-run independently), or delete (and kill) it using the
-@w{@code{delete fork}} command.
+@table @code
+@kindex set follow-exec-mode
+@item set follow-exec-mode @var{mode}
+
+Set debugger response to a program call of @code{exec}. An
+@code{exec} call replaces the program image of a process.
+
+@code{follow-exec-mode} can be:
@table @code
-@kindex detach fork @var{fork-id}
-@item detach fork @var{fork-id}
-Detach from the process identified by @value{GDBN} fork number
-@var{fork-id}, and remove it from the fork list. The process will be
-allowed to run independently.
+@item new
+@value{GDBN} creates a new inferior and rebinds the process to this
+new inferior. The program the process was running before the
+@code{exec} call can be restarted afterwards by restarting the
+original inferior.
-@kindex delete fork @var{fork-id}
-@item delete fork @var{fork-id}
-Kill the process identified by @value{GDBN} fork number @var{fork-id},
-and remove it from the fork list.
+For example:
-@end table
+@smallexample
+(@value{GDBP}) info inferiors
+(gdb) info inferior
+ Id Description Executable
+* 1 <null> prog1
+(@value{GDBP}) run
+process 12020 is executing new program: prog2
+Program exited normally.
+(@value{GDBP}) info inferiors
+ Id Description Executable
+* 2 <null> prog2
+ 1 <null> prog1
+@end smallexample
-If you ask to debug a child process and a @code{vfork} is followed by an
-@code{exec}, @value{GDBN} executes the new target up to the first
-breakpoint in the new target. If you have a breakpoint set on
-@code{main} in your original program, the breakpoint will also be set on
-the child process's @code{main}.
+@item same
+@value{GDBN} keeps the process bound to the same inferior. The new
+executable image replaces the previous executable loaded in the
+inferior. Restarting the inferior after the @code{exec} call, with
+e.g., the @code{run} command, restarts the executable the process was
+running after the @code{exec} call. This is the default mode.
-When a child process is spawned by @code{vfork}, you cannot debug the
-child or parent until an @code{exec} call completes.
+For example:
-If you issue a @code{run} command to @value{GDBN} after an @code{exec}
-call executes, the new target restarts. To restart the parent process,
-use the @code{file} command with the parent executable name as its
-argument.
+@smallexample
+(@value{GDBP}) info inferiors
+ Id Description Executable
+* 1 <null> prog1
+(@value{GDBP}) run
+process 12020 is executing new program: prog2
+Program exited normally.
+(@value{GDBP}) info inferiors
+ Id Description Executable
+* 1 <null> prog2
+@end smallexample
+
+@end table
+@end table
You can use the @code{catch} command to make @value{GDBN} stop whenever
a @code{fork}, @code{vfork}, or @code{exec} call is made. @xref{Set
@xref{Ambiguous Expressions,,Ambiguous Expressions}, for a discussion of
that situation.
+It is also possible to insert a breakpoint that will stop the program
+only if a specific thread (@pxref{Thread-Specific Breakpoints})
+or a specific task (@pxref{Ada Tasks}) hits that breakpoint.
+
@item break
When called without any arguments, @code{break} sets a breakpoint at
the next instruction to be executed in the selected stack frame
A call to @code{exec}. This is currently only available for HP-UX
and @sc{gnu}/Linux.
+@item syscall
+@itemx syscall @r{[}@var{name} @r{|} @var{number}@r{]} @r{...}
+@cindex break on a system call.
+A call to or return from a system call, a.k.a.@: @dfn{syscall}. A
+syscall is a mechanism for application programs to request a service
+from the operating system (OS) or one of the OS system services.
+@value{GDBN} can catch some or all of the syscalls issued by the
+debuggee, and show the related information for each syscall. If no
+argument is specified, calls to and returns from all system calls
+will be caught.
+
+@var{name} can be any system call name that is valid for the
+underlying OS. Just what syscalls are valid depends on the OS. On
+GNU and Unix systems, you can find the full list of valid syscall
+names on @file{/usr/include/asm/unistd.h}.
+
+@c For MS-Windows, the syscall names and the corresponding numbers
+@c can be found, e.g., on this URL:
+@c http://www.metasploit.com/users/opcode/syscalls.html
+@c but we don't support Windows syscalls yet.
+
+Normally, @value{GDBN} knows in advance which syscalls are valid for
+each OS, so you can use the @value{GDBN} command-line completion
+facilities (@pxref{Completion,, command completion}) to list the
+available choices.
+
+You may also specify the system call numerically. A syscall's
+number is the value passed to the OS's syscall dispatcher to
+identify the requested service. When you specify the syscall by its
+name, @value{GDBN} uses its database of syscalls to convert the name
+into the corresponding numeric code, but using the number directly
+may be useful if @value{GDBN}'s database does not have the complete
+list of syscalls on your system (e.g., because @value{GDBN} lags
+behind the OS upgrades).
+
+The example below illustrates how this command works if you don't provide
+arguments to it:
+
+@smallexample
+(@value{GDBP}) catch syscall
+Catchpoint 1 (syscall)
+(@value{GDBP}) r
+Starting program: /tmp/catch-syscall
+
+Catchpoint 1 (call to syscall 'close'), \
+ 0xffffe424 in __kernel_vsyscall ()
+(@value{GDBP}) c
+Continuing.
+
+Catchpoint 1 (returned from syscall 'close'), \
+ 0xffffe424 in __kernel_vsyscall ()
+(@value{GDBP})
+@end smallexample
+
+Here is an example of catching a system call by name:
+
+@smallexample
+(@value{GDBP}) catch syscall chroot
+Catchpoint 1 (syscall 'chroot' [61])
+(@value{GDBP}) r
+Starting program: /tmp/catch-syscall
+
+Catchpoint 1 (call to syscall 'chroot'), \
+ 0xffffe424 in __kernel_vsyscall ()
+(@value{GDBP}) c
+Continuing.
+
+Catchpoint 1 (returned from syscall 'chroot'), \
+ 0xffffe424 in __kernel_vsyscall ()
+(@value{GDBP})
+@end smallexample
+
+An example of specifying a system call numerically. In the case
+below, the syscall number has a corresponding entry in the XML
+file, so @value{GDBN} finds its name and prints it:
+
+@smallexample
+(@value{GDBP}) catch syscall 252
+Catchpoint 1 (syscall(s) 'exit_group')
+(@value{GDBP}) r
+Starting program: /tmp/catch-syscall
+
+Catchpoint 1 (call to syscall 'exit_group'), \
+ 0xffffe424 in __kernel_vsyscall ()
+(@value{GDBP}) c
+Continuing.
+
+Program exited normally.
+(@value{GDBP})
+@end smallexample
+
+However, there can be situations when there is no corresponding name
+in XML file for that syscall number. In this case, @value{GDBN} prints
+a warning message saying that it was not able to find the syscall name,
+but the catchpoint will be set anyway. See the example below:
+
+@smallexample
+(@value{GDBP}) catch syscall 764
+warning: The number '764' does not represent a known syscall.
+Catchpoint 2 (syscall 764)
+(@value{GDBP})
+@end smallexample
+
+If you configure @value{GDBN} using the @samp{--without-expat} option,
+it will not be able to display syscall names. Also, if your
+architecture does not have an XML file describing its system calls,
+you will not be able to see the syscall names. It is important to
+notice that these two features are used for accessing the syscall
+name database. In either case, you will see a warning like this:
+
+@smallexample
+(@value{GDBP}) catch syscall
+warning: Could not open "syscalls/i386-linux.xml"
+warning: Could not load the syscall XML file 'syscalls/i386-linux.xml'.
+GDB will not be able to display syscall names.
+Catchpoint 1 (syscall)
+(@value{GDBP})
+@end smallexample
+
+Of course, the file name will change depending on your architecture and system.
+
+Still using the example above, you can also try to catch a syscall by its
+number. In this case, you would see something like:
+
+@smallexample
+(@value{GDBP}) catch syscall 252
+Catchpoint 1 (syscall(s) 252)
+@end smallexample
+
+Again, in this case @value{GDBN} would not be able to display syscall's names.
+
@item fork
A call to @code{fork}. This is currently only available for HP-UX
and @sc{gnu}/Linux.
Break conditions can have side effects, and may even call functions in
your program. This can be useful, for example, to activate functions
that log program progress, or to use your own print functions to
-format special data structures. The effects are completely predictable
+format special data structures. The effects are completely predictable
unless there is another enabled breakpoint at the same address. (In
that case, @value{GDBN} might see the other breakpoint first and stop your
program without checking the condition of this one.) Note that
Display the current scheduler locking mode.
@end table
+@cindex resume threads of multiple processes simultaneously
+By default, when you issue one of the execution commands such as
+@code{continue}, @code{next} or @code{step}, @value{GDBN} allows only
+threads of the current inferior to run. For example, if @value{GDBN}
+is attached to two inferiors, each with two threads, the
+@code{continue} command resumes only the two threads of the current
+inferior. This is useful, for example, when you debug a program that
+forks and you want to hold the parent stopped (so that, for instance,
+it doesn't run to exit), while you debug the child. In other
+situations, you may not be interested in inspecting the current state
+of any of the processes @value{GDBN} is attached to, and you may want
+to resume them all until some breakpoint is hit. In the latter case,
+you can instruct @value{GDBN} to allow all threads of all the
+inferiors to run with the @w{@code{set schedule-multiple}} command.
+
+@table @code
+@kindex set schedule-multiple
+@item set schedule-multiple
+Set the mode for allowing threads of multiple processes to be resumed
+when an execution command is issued. When @code{on}, all threads of
+all processes are allowed to run. When @code{off}, only the threads
+of the current process are resumed. The default is @code{off}. The
+@code{scheduler-locking} mode takes precedence when set to @code{on},
+or while you are stepping and set to @code{step}.
+
+@item show schedule-multiple
+Display the current mode for resuming the execution of threads of
+multiple processes.
+@end table
+
@node Non-Stop Mode
@subsection Non-Stop Mode
program.
You can use the @code{thread} qualifier on conditional breakpoints as
-well; in this case, place @samp{thread @var{threadno}} before the
-breakpoint condition, like this:
+well; in this case, place @samp{thread @var{threadno}} before or
+after the breakpoint condition, like this:
@smallexample
(@value{GDBP}) break frik.c:13 thread 28 if bartab > lim
to the caller of that function, @emph{before} the function was called,
just as the normal @code{next} command would take you from the last
line of a function back to its return to its caller
-@footnote{Unles the code is too heavily optimized.}.
+@footnote{Unless the code is too heavily optimized.}.
@kindex reverse-nexti
@kindex rni @r{(@code{reverse-nexti})}
@end table
+@node Process Record and Replay
+@chapter Recording Inferior's Execution and Replaying It
+@cindex process record and replay
+@cindex recording inferior's execution and replaying it
+
+On some platforms, @value{GDBN} provides a special @dfn{process record
+and replay} target that can record a log of the process execution, and
+replay it later with both forward and reverse execution commands.
+
+@cindex replay mode
+When this target is in use, if the execution log includes the record
+for the next instruction, @value{GDBN} will debug in @dfn{replay
+mode}. In the replay mode, the inferior does not really execute code
+instructions. Instead, all the events that normally happen during
+code execution are taken from the execution log. While code is not
+really executed in replay mode, the values of registers (including the
+program counter register) and the memory of the inferior are still
+changed as they normally would. Their contents are taken from the
+execution log.
+
+@cindex record mode
+If the record for the next instruction is not in the execution log,
+@value{GDBN} will debug in @dfn{record mode}. In this mode, the
+inferior executes normally, and @value{GDBN} records the execution log
+for future replay.
+
+The process record and replay target supports reverse execution
+(@pxref{Reverse Execution}), even if the platform on which the
+inferior runs does not. However, the reverse execution is limited in
+this case by the range of the instructions recorded in the execution
+log. In other words, reverse execution on platforms that don't
+support it directly can only be done in the replay mode.
+
+When debugging in the reverse direction, @value{GDBN} will work in
+replay mode as long as the execution log includes the record for the
+previous instruction; otherwise, it will work in record mode, if the
+platform supports reverse execution, or stop if not.
+
+For architecture environments that support process record and replay,
+@value{GDBN} provides the following commands:
+
+@table @code
+@kindex target record
+@kindex record
+@kindex rec
+@item target record
+This command starts the process record and replay target. The process
+record and replay target can only debug a process that is already
+running. Therefore, you need first to start the process with the
+@kbd{run} or @kbd{start} commands, and then start the recording with
+the @kbd{target record} command.
+
+Both @code{record} and @code{rec} are aliases of @code{target record}.
+
+@cindex displaced stepping, and process record and replay
+Displaced stepping (@pxref{Maintenance Commands,, displaced stepping})
+will be automatically disabled when process record and replay target
+is started. That's because the process record and replay target
+doesn't support displaced stepping.
+
+@cindex non-stop mode, and process record and replay
+@cindex asynchronous execution, and process record and replay
+If the inferior is in the non-stop mode (@pxref{Non-Stop Mode}) or in
+the asynchronous execution mode (@pxref{Background Execution}), the
+process record and replay target cannot be started because it doesn't
+support these two modes.
+
+@kindex record stop
+@kindex rec s
+@item record stop
+Stop the process record and replay target. When process record and
+replay target stops, the entire execution log will be deleted and the
+inferior will either be terminated, or will remain in its final state.
+
+When you stop the process record and replay target in record mode (at
+the end of the execution log), the inferior will be stopped at the
+next instruction that would have been recorded. In other words, if
+you record for a while and then stop recording, the inferior process
+will be left in the same state as if the recording never happened.
+
+On the other hand, if the process record and replay target is stopped
+while in replay mode (that is, not at the end of the execution log,
+but at some earlier point), the inferior process will become ``live''
+at that earlier state, and it will then be possible to continue the
+usual ``live'' debugging of the process from that state.
+
+When the inferior process exits, or @value{GDBN} detaches from it,
+process record and replay target will automatically stop itself.
+
+@kindex set record insn-number-max
+@item set record insn-number-max @var{limit}
+Set the limit of instructions to be recorded. Default value is 200000.
+
+If @var{limit} is a positive number, then @value{GDBN} will start
+deleting instructions from the log once the number of the record
+instructions becomes greater than @var{limit}. For every new recorded
+instruction, @value{GDBN} will delete the earliest recorded
+instruction to keep the number of recorded instructions at the limit.
+(Since deleting recorded instructions loses information, @value{GDBN}
+lets you control what happens when the limit is reached, by means of
+the @code{stop-at-limit} option, described below.)
+
+If @var{limit} is zero, @value{GDBN} will never delete recorded
+instructions from the execution log. The number of recorded
+instructions is unlimited in this case.
+
+@kindex show record insn-number-max
+@item show record insn-number-max
+Show the limit of instructions to be recorded.
+
+@kindex set record stop-at-limit
+@item set record stop-at-limit
+Control the behavior when the number of recorded instructions reaches
+the limit. If ON (the default), @value{GDBN} will stop when the limit
+is reached for the first time and ask you whether you want to stop the
+inferior or continue running it and recording the execution log. If
+you decide to continue recording, each new recorded instruction will
+cause the oldest one to be deleted.
+
+If this option is OFF, @value{GDBN} will automatically delete the
+oldest record to make room for each new one, without asking.
+
+@kindex show record stop-at-limit
+@item show record stop-at-limit
+Show the current setting of @code{stop-at-limit}.
+
+@kindex info record
+@item info record
+Show various statistics about the state of process record and its
+in-memory execution log buffer, including:
+
+@itemize @bullet
+@item
+Whether in record mode or replay mode.
+@item
+Lowest recorded instruction number (counting from when the current execution log started recording instructions).
+@item
+Highest recorded instruction number.
+@item
+Current instruction about to be replayed (if in replay mode).
+@item
+Number of instructions contained in the execution log.
+@item
+Maximum number of instructions that may be contained in the execution log.
+@end itemize
+
+@kindex record delete
+@kindex rec del
+@item record delete
+When record target runs in replay mode (``in the past''), delete the
+subsequent execution log and begin to record a new execution log starting
+from the current address. This means you will abandon the previously
+recorded ``future'' and begin recording a new ``future''.
+@end table
+
+
@node Stack
@chapter Examining the Stack
@group
#0 m4_traceon (obs=0x24eb0, argc=1, argv=0x2b8c8)
at builtin.c:993
-#1 0x6e38 in expand_macro (sym=0x2b600) at macro.c:242
+#1 0x6e38 in expand_macro (sym=0x2b600, data=...) at macro.c:242
#2 0x6840 in expand_token (obs=0x0, t=177664, td=0xf7fffb08)
at macro.c:71
(More stack frames follow...)
value, indicating that your program has stopped at the beginning of the
code for line @code{993} of @code{builtin.c}.
+@noindent
+The value of parameter @code{data} in frame 1 has been replaced by
+@code{@dots{}}. By default, @value{GDBN} prints the value of a parameter
+only if it is a scalar (integer, pointer, enumeration, etc). See command
+@kbd{set print frame-arguments} in @ref{Print Settings} for more details
+on how to configure the way function parameter values are printed.
+
@cindex value optimized out, in backtrace
@cindex function call arguments, optimized out
If your program was compiled with optimizations, some compilers will
located at the original location, a substitution rule is the only
method available to point @value{GDBN} at the new location.
+@cindex @samp{--with-relocated-sources}
+@cindex default source path substitution
+You can configure a default source path substitution rule by
+configuring @value{GDBN} with the
+@samp{--with-relocated-sources=@var{dir}} option. The @var{dir}
+should be the name of a directory under @value{GDBN}'s configured
+prefix (set with @samp{--prefix} or @samp{--exec-prefix}), and
+directory names in debug information under @var{dir} will be adjusted
+automatically if the installed @value{GDBN} is moved to a new
+location. This is useful if @value{GDBN}, libraries or executables
+with debug information and corresponding source code are being moved
+together.
+
@table @code
@item directory @var{dirname} @dots{}
@item dir @var{dirname} @dots{}
@cindex listing machine instructions
@item disassemble
@itemx disassemble /m
+@itemx disassemble /r
This specialized command dumps a range of memory as machine
instructions. It can also print mixed source+disassembly by specifying
-the @code{/m} modifier.
+the @code{/m} modifier and print the raw instructions in hex as well as
+in symbolic form by specifying the @code{/r}.
The default memory range is the function surrounding the
program counter of the selected frame. A single argument to this
command is a program counter value; @value{GDBN} dumps the function
-surrounding this value. Two arguments specify a range of addresses
-(first inclusive, second exclusive) to dump.
+surrounding this value. When two arguments are given, they should
+be separated by a comma, possibly surrounded by whitespace. The
+arguments specify a range of addresses (first inclusive, second exclusive)
+to dump. In that case, the name of the function is also printed (since
+there could be several functions in the given range).
+
+The argument(s) can be any expression yielding a numeric value, such as
+@samp{0x32c4}, @samp{&main+10} or @samp{$pc - 8}.
+
+If the range of memory being disassembled contains current program counter,
+the instruction at that location is shown with a @code{=>} marker.
@end table
The following example shows the disassembly of a range of addresses of
HP PA-RISC 2.0 code:
@smallexample
-(@value{GDBP}) disas 0x32c4 0x32e4
+(@value{GDBP}) disas 0x32c4, 0x32e4
Dump of assembler code from 0x32c4 to 0x32e4:
-0x32c4 <main+204>: addil 0,dp
-0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
-0x32cc <main+212>: ldil 0x3000,r31
-0x32d0 <main+216>: ble 0x3f8(sr4,r31)
-0x32d4 <main+220>: ldo 0(r31),rp
-0x32d8 <main+224>: addil -0x800,dp
-0x32dc <main+228>: ldo 0x588(r1),r26
-0x32e0 <main+232>: ldil 0x3000,r31
+ 0x32c4 <main+204>: addil 0,dp
+ 0x32c8 <main+208>: ldw 0x22c(sr0,r1),r26
+ 0x32cc <main+212>: ldil 0x3000,r31
+ 0x32d0 <main+216>: ble 0x3f8(sr4,r31)
+ 0x32d4 <main+220>: ldo 0(r31),rp
+ 0x32d8 <main+224>: addil -0x800,dp
+ 0x32dc <main+228>: ldo 0x588(r1),r26
+ 0x32e0 <main+232>: ldil 0x3000,r31
End of assembler dump.
@end smallexample
-Here is an example showing mixed source+assembly for Intel x86:
+Here is an example showing mixed source+assembly for Intel x86, when the
+program is stopped just after function prologue:
@smallexample
(@value{GDBP}) disas /m main
Dump of assembler code for function main:
5 @{
-0x08048330 <main+0>: push %ebp
-0x08048331 <main+1>: mov %esp,%ebp
-0x08048333 <main+3>: sub $0x8,%esp
-0x08048336 <main+6>: and $0xfffffff0,%esp
-0x08048339 <main+9>: sub $0x10,%esp
+ 0x08048330 <+0>: push %ebp
+ 0x08048331 <+1>: mov %esp,%ebp
+ 0x08048333 <+3>: sub $0x8,%esp
+ 0x08048336 <+6>: and $0xfffffff0,%esp
+ 0x08048339 <+9>: sub $0x10,%esp
6 printf ("Hello.\n");
-0x0804833c <main+12>: movl $0x8048440,(%esp)
-
0x08048343 <main+19>: call 0x8048284 <puts@@plt>
+=> 0x0804833c <+12>: movl $0x8048440,(%esp)
+
0x08048343 <+19>: call 0x8048284 <puts@@plt>
7 return 0;
8 @}
-0x08048348 <main+24>: mov $0x0,%eax
-0x0804834d <main+29>: leave
-0x0804834e <main+30>: ret
+ 0x08048348 <+24>: mov $0x0,%eax
+ 0x0804834d <+29>: leave
+ 0x0804834e <+30>: ret
End of assembler dump.
@end smallexample
@kindex show disassemble-next-line
@item set disassemble-next-line
@itemx show disassemble-next-line
-Control whether or not @value{GDBN} will disassemble next source line
-when execution stops. If ON, GDB will display disassembly of the next
-source line when execution of the program being debugged stops.
-If AUTO (which is the default), or there's no line info to determine
-the source line of the next instruction, display disassembly of next
-instruction instead.
+Control whether or not @value{GDBN} will disassemble the next source
+line or instruction when execution stops. If ON, @value{GDBN} will
+display disassembly of the next source line when execution of the
+program being debugged stops. This is @emph{in addition} to
+displaying the source line itself, which @value{GDBN} always does if
+possible. If the next source line cannot be displayed for some reason
+(e.g., if @value{GDBN} cannot find the source file, or there's no line
+info in the debug info), @value{GDBN} will display disassembly of the
+next @emph{instruction} instead of showing the next source line. If
+AUTO, @value{GDBN} will display disassembly of next instruction only
+if the source line cannot be displayed. This setting causes
+@value{GDBN} to display some feedback when you step through a function
+with no line info or whose source file is unavailable. The default is
+OFF, which means never display the disassembly of the next line or
+instruction.
@end table
@code{char}, @w{@code{unsigned char}}, and @w{@code{signed char}} as
strings. Single-byte members of a vector are displayed as an integer
array.
+
+@item r
+@cindex raw printing
+Print using the @samp{raw} formatting. By default, @value{GDBN} will
+use a type-specific pretty-printer. The @samp{r} format bypasses any
+pretty-printer which might exist for the value's type.
@end table
For example, to print the program counter in hex (@pxref{Registers}), type
the repeat count @var{n} is used again; the other arguments default as
for successive uses of @code{x}.
+When examining machine instructions, the instruction at current program
+counter is shown with a @code{=>} marker. For example:
+
+@smallexample
+(@value{GDBP}) x/5i $pc-6
+ 0x804837f <main+11>: mov %esp,%ebp
+ 0x8048381 <main+13>: push %ecx
+ 0x8048382 <main+14>: sub $0x4,%esp
+=> 0x8048385 <main+17>: movl $0x8048460,(%esp)
+ 0x804838c <main+24>: call 0x80482d4 <puts@@plt>
+@end smallexample
+
@cindex @code{$_}, @code{$__}, and value history
The addresses and contents printed by the @code{x} command are not saved
in the value history because there is often too much of them and they
If the number is 0, then the printing is unlimited.
@item set print frame-arguments @var{value}
+@kindex set print frame-arguments
@cindex printing frame argument values
@cindex print all frame argument values
@cindex print frame argument values for scalars only
@table @code
@item all
-The values of all arguments are printed. This is the default.
+The values of all arguments are printed.
@item scalars
Print the value of an argument only if it is a scalar. The value of more
complex arguments such as arrays, structures, unions, etc, is replaced
-by @code{@dots{}}. Here is an example where only scalar arguments are shown:
+by @code{@dots{}}. This is the default. Here is an example where
+only scalar arguments are shown:
@smallexample
#1 0x08048361 in call_me (i=3, s=@dots{}, ss=0xbf8d508c, u=@dots{}, e=green)
@end smallexample
@end table
-By default, all argument values are always printed. But this command
-can be useful in several cases. For instance, it can be used to reduce
-the amount of information printed in each frame, making the backtrace
-more readable. Also, this command can be used to improve performance
-when displaying Ada frames, because the computation of large arguments
-can sometimes be CPU-intensive, especiallly in large applications.
-Setting @code{print frame-arguments} to @code{scalars} or @code{none}
-avoids this computation, thus speeding up the display of each Ada frame.
+By default, only scalar arguments are printed. This command can be used
+to configure the debugger to print the value of all arguments, regardless
+of their type. However, it is often advantageous to not print the value
+of more complex parameters. For instance, it reduces the amount of
+information printed in each frame, making the backtrace more readable.
+Also, it improves performance when displaying Ada frames, because
+the computation of large arguments can sometimes be CPU-intensive,
+especially in large applications. Setting @code{print frame-arguments}
+to @code{scalars} (the default) or @code{none} avoids this computation,
+thus speeding up the display of each Ada frame.
@item show print frame-arguments
Show how the value of arguments should be displayed when printing a frame.
@item $_siginfo
@vindex $_siginfo@r{, convenience variable}
-The variable @code{$_siginfo} is bound to extra signal information
-inspection (@pxref{extra signal information}).
+The variable @code{$_siginfo} contains extra signal information
+(@pxref{extra signal information}). Note that @code{$_siginfo}
+could be empty, if the application has not yet received any signals.
+For example, it will be empty before you execute the @code{run} command.
@end table
On HP-UX systems, if you refer to a function or variable name that
begins with a dollar sign, @value{GDBN} searches for a user or system
name first, before it searches for a convenience variable.
+@cindex convenience functions
+@value{GDBN} also supplies some @dfn{convenience functions}. These
+have a syntax similar to convenience variables. A convenience
+function can be used in an expression just like an ordinary function;
+however, a convenience function is implemented internally to
+@value{GDBN}.
+
+@table @code
+@item help function
+@kindex help function
+@cindex show all convenience functions
+Print a list of all convenience functions.
+@end table
+
@node Registers
@section Registers
@table @code
@item set target-charset @var{charset}
@kindex set target-charset
-Set the current target character set to @var{charset}. We list the
-character set names @value{GDBN} recognizes below, but if you type
-@code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will
-list the target character sets it supports.
-@end table
+Set the current target character set to @var{charset}. To display the
+list of supported target character sets, type
+@kbd{@w{set target-charset @key{TAB}@key{TAB}}}.
-@table @code
@item set host-charset @var{charset}
@kindex set host-charset
Set the current host character set to @var{charset}.
By default, @value{GDBN} uses a host character set appropriate to the
system it is running on; you can override that default using the
-@code{set host-charset} command.
+@code{set host-charset} command. On some systems, @value{GDBN} cannot
+automatically determine the appropriate host character set. In this
+case, @value{GDBN} uses @samp{UTF-8}.
@value{GDBN} can only use certain character sets as its host character
-set. We list the character set names @value{GDBN} recognizes below, and
-indicate which can be host character sets, but if you type
-@code{set target-charset} followed by @key{TAB}@key{TAB}, @value{GDBN} will
-list the host character sets it supports.
+set. If you type @kbd{@w{set target-charset @key{TAB}@key{TAB}}},
+@value{GDBN} will list the host character sets it supports.
@item set charset @var{charset}
@kindex set charset
Set the current host and target character sets to @var{charset}. As
-above, if you type @code{set charset} followed by @key{TAB}@key{TAB},
-@value{GDBN} will list the name of the character sets that can be used
+above, if you type @kbd{@w{set charset @key{TAB}@key{TAB}}},
+@value{GDBN} will list the names of the character sets that can be used
for both host and target.
-
@item show charset
@kindex show charset
-Show the names of the current host and target charsets.
+Show the names of the current host and target character sets.
-@itemx show host-charset
+@item show host-charset
@kindex show host-charset
-Show the name of the current host charset.
+Show the name of the current host character set.
-@itemx show target-charset
+@item show target-charset
@kindex show target-charset
-Show the name of the current target charset.
-
-@end table
-
-@value{GDBN} currently includes support for the following character
-sets:
-
-@table @code
-
-@item ASCII
-@cindex ASCII character set
-Seven-bit U.S. @sc{ascii}. @value{GDBN} can use this as its host
-character set.
-
-@item ISO-8859-1
-@cindex ISO 8859-1 character set
-@cindex ISO Latin 1 character set
-The ISO Latin 1 character set. This extends @sc{ascii} with accented
-characters needed for French, German, and Spanish. @value{GDBN} can use
-this as its host character set.
+Show the name of the current target character set.
-@item EBCDIC-US
-@itemx IBM1047
-@cindex EBCDIC character set
-@cindex IBM1047 character set
-Variants of the @sc{ebcdic} character set, used on some of IBM's
-mainframe operating systems. (@sc{gnu}/Linux on the S/390 uses U.S. @sc{ascii}.)
-@value{GDBN} cannot use these as its host character set.
+@item set target-wide-charset @var{charset}
+@kindex set target-wide-charset
+Set the current target's wide character set to @var{charset}. This is
+the character set used by the target's @code{wchar_t} type. To
+display the list of supported wide character sets, type
+@kbd{@w{set target-wide-charset @key{TAB}@key{TAB}}}.
+@item show target-wide-charset
+@kindex show target-wide-charset
+Show the name of the current target's wide character set.
@end table
-Note that these are all single-byte character sets. More work inside
-@value{GDBN} is needed to support multi-byte or variable-width character
-encodings, like the UTF-8 and UCS-2 encodings of Unicode.
-
Here is an example of @value{GDBN}'s character set support in action.
Assume that the following source code has been placed in the file
@file{charset-test.c}:
@section Caching Data of Remote Targets
@cindex caching data of remote targets
-@value{GDBN} can cache data exchanged between the debugger and a
+@value{GDBN} caches data exchanged between the debugger and a
remote target (@pxref{Remote Debugging}). Such caching generally improves
performance, because it reduces the overhead of the remote protocol by
-bundling memory reads and writes into large chunks. Unfortunately,
-@value{GDBN} does not currently know anything about volatile
-registers, and thus data caching will produce incorrect results when
-volatile registers are in use.
+bundling memory reads and writes into large chunks. Unfortunately, simply
+caching everything would lead to incorrect results, since @value{GDBN}
+does not necessarily know anything about volatile values, memory-mapped I/O
+addresses, etc. Furthermore, in non-stop mode (@pxref{Non-Stop Mode})
+memory can be changed @emph{while} a gdb command is executing.
+Therefore, by default, @value{GDBN} only caches data
+known to be on the stack@footnote{In non-stop mode, it is moderately
+rare for a running thread to modify the stack of a stopped thread
+in a way that would interfere with a backtrace, and caching of
+stack reads provides a significant speed up of remote backtraces.}.
+Other regions of memory can be explicitly marked as
+cacheable; see @pxref{Memory Region Attributes}.
@table @code
@kindex set remotecache
@item set remotecache on
@itemx set remotecache off
-Set caching state for remote targets. When @code{ON}, use data
-caching. By default, this option is @code{OFF}.
+This option no longer does anything; it exists for compatibility
+with old scripts.
@kindex show remotecache
@item show remotecache
-Show the current state of data caching for remote targets.
+Show the current state of the obsolete remotecache flag.
+
+@kindex set stack-cache
+@item set stack-cache on
+@itemx set stack-cache off
+Enable or disable caching of stack accesses. When @code{ON}, use
+caching. By default, this option is @code{ON}.
+
+@kindex show stack-cache
+@item show stack-cache
+Show the current state of data caching for memory accesses.
@kindex info dcache
-@item info dcache
+@item info dcache @r{[}line@r{]}
Print the information about the data cache performance. The
-information displayed includes: the dcache width and depth; and for
-each cache line, how many times it was referenced, and its data and
-state (invalid, dirty, valid). This command is useful for debugging
-the data cache operation.
+information displayed includes the dcache width and depth, and for
+each cache line, its number, address, and how many times it was
+referenced. This command is useful for debugging the data cache
+operation.
+
+If a line number is specified, the contents of that line will be
+printed in hex.
@end table
@node Searching Memory
$2 = (void *) 0x8049560
@end smallexample
+@node Optimized Code
+@chapter Debugging Optimized Code
+@cindex optimized code, debugging
+@cindex debugging optimized code
+
+Almost all compilers support optimization. With optimization
+disabled, the compiler generates assembly code that corresponds
+directly to your source code, in a simplistic way. As the compiler
+applies more powerful optimizations, the generated assembly code
+diverges from your original source code. With help from debugging
+information generated by the compiler, @value{GDBN} can map from
+the running program back to constructs from your original source.
+
+@value{GDBN} is more accurate with optimization disabled. If you
+can recompile without optimization, it is easier to follow the
+progress of your program during debugging. But, there are many cases
+where you may need to debug an optimized version.
+
+When you debug a program compiled with @samp{-g -O}, remember that the
+optimizer has rearranged your code; the debugger shows you what is
+really there. Do not be too surprised when the execution path does not
+exactly match your source file! An extreme example: if you define a
+variable, but never use it, @value{GDBN} never sees that
+variable---because the compiler optimizes it out of existence.
+
+Some things do not work as well with @samp{-g -O} as with just
+@samp{-g}, particularly on machines with instruction scheduling. If in
+doubt, recompile with @samp{-g} alone, and if this fixes the problem,
+please report it to us as a bug (including a test case!).
+@xref{Variables}, for more information about debugging optimized code.
+
+@menu
+* Inline Functions:: How @value{GDBN} presents inlining
+@end menu
+
+@node Inline Functions
+@section Inline Functions
+@cindex inline functions, debugging
+
+@dfn{Inlining} is an optimization that inserts a copy of the function
+body directly at each call site, instead of jumping to a shared
+routine. @value{GDBN} displays inlined functions just like
+non-inlined functions. They appear in backtraces. You can view their
+arguments and local variables, step into them with @code{step}, skip
+them with @code{next}, and escape from them with @code{finish}.
+You can check whether a function was inlined by using the
+@code{info frame} command.
+
+For @value{GDBN} to support inlined functions, the compiler must
+record information about inlining in the debug information ---
+@value{NGCC} using the @sc{dwarf 2} format does this, and several
+other compilers do also. @value{GDBN} only supports inlined functions
+when using @sc{dwarf 2}. Versions of @value{NGCC} before 4.1
+do not emit two required attributes (@samp{DW_AT_call_file} and
+@samp{DW_AT_call_line}); @value{GDBN} does not display inlined
+function calls with earlier versions of @value{NGCC}. It instead
+displays the arguments and local variables of inlined functions as
+local variables in the caller.
+
+The body of an inlined function is directly included at its call site;
+unlike a non-inlined function, there are no instructions devoted to
+the call. @value{GDBN} still pretends that the call site and the
+start of the inlined function are different instructions. Stepping to
+the call site shows the call site, and then stepping again shows
+the first line of the inlined function, even though no additional
+instructions are executed.
+
+This makes source-level debugging much clearer; you can see both the
+context of the call and then the effect of the call. Only stepping by
+a single instruction using @code{stepi} or @code{nexti} does not do
+this; single instruction steps always show the inlined body.
+
+There are some ways that @value{GDBN} does not pretend that inlined
+function calls are the same as normal calls:
+
+@itemize @bullet
+@item
+You cannot set breakpoints on inlined functions. @value{GDBN}
+either reports that there is no symbol with that name, or else sets the
+breakpoint only on non-inlined copies of the function. This limitation
+will be removed in a future version of @value{GDBN}; until then,
+set a breakpoint by line number on the first line of the inlined
+function instead.
+
+@item
+Setting breakpoints at the call site of an inlined function may not
+work, because the call site does not contain any code. @value{GDBN}
+may incorrectly move the breakpoint to the next line of the enclosing
+function, after the call. This limitation will be removed in a future
+version of @value{GDBN}; until then, set a breakpoint on an earlier line
+or inside the inlined function instead.
+
+@item
+@value{GDBN} cannot locate the return value of inlined calls after
+using the @code{finish} command. This is a limitation of compiler-generated
+debugging information; after @code{finish}, you can step to the next line
+and print a variable where your program stored the return value.
+
+@end itemize
+
+
@node Macros
@chapter C Preprocessor Macros
@cindex definition, showing a macro's
@item info macro @var{macro}
Show the definition of the macro named @var{macro}, and describe the
-source location where that definition was established.
+source location or compiler command-line where that definition was established.
@kindex macro define
@cindex user-defined macros
(@value{GDBP})
@end smallexample
+In addition to source files, macros can be defined on the compilation command
+line using the @option{-D@var{name}=@var{value}} syntax. For macros defined in
+such a way, @value{GDBN} displays the location of their definition as line zero
+of the source file submitted to the compiler.
-@node Tracepoints
-@chapter Tracepoints
-@c This chapter is based on the documentation written by Michael
-@c Snyder, David Taylor, Jim Blandy, and Elena Zannoni.
+@smallexample
+(@value{GDBP}) info macro __STDC__
+Defined at /home/jimb/gdb/macros/play/sample.c:0
+-D__STDC__=1
+(@value{GDBP})
+@end smallexample
+
+
+@node Tracepoints
+@chapter Tracepoints
+@c This chapter is based on the documentation written by Michael
+@c Snyder, David Taylor, Jim Blandy, and Elena Zannoni.
@cindex tracepoints
In some applications, it is not feasible for the debugger to interrupt
packets used to implement tracepoints are described in @ref{Tracepoint
Packets}.
+It is also possible to get trace data from a file, in a manner reminiscent
+of corefiles; you specify the filename, and use @code{tfind} to search
+through the file. @xref{Trace Files}, for more details.
+
This chapter describes the tracepoint commands and features.
@menu
* Set Tracepoints::
* Analyze Collected Data::
* Tracepoint Variables::
+* Trace Files::
@end menu
@node Set Tracepoints
@section Commands to Set Tracepoints
Before running such a @dfn{trace experiment}, an arbitrary number of
-tracepoints can be set. Like a breakpoint (@pxref{Set Breaks}), a
-tracepoint has a number assigned to it by @value{GDBN}. Like with
-breakpoints, tracepoint numbers are successive integers starting from
-one. Many of the commands associated with tracepoints take the
-tracepoint number as their argument, to identify which tracepoint to
-work on.
+tracepoints can be set. A tracepoint is actually a special type of
+breakpoint (@pxref{Set Breaks}), so you can manipulate it using
+standard breakpoint commands. For instance, as with breakpoints,
+tracepoint numbers are successive integers starting from one, and many
+of the commands associated with tracepoints take the tracepoint number
+as their argument, to identify which tracepoint to work on.
For each tracepoint, you can specify, in advance, some arbitrary set
of data that you want the target to collect in the trace buffer when
commands to examine the values these data had at the time the
tracepoint was hit.
+Tracepoints do not support every breakpoint feature. Conditional
+expressions and ignore counts on tracepoints have no effect, and
+tracepoints cannot run @value{GDBN} commands when they are
+hit. Tracepoints may not be thread-specific either.
+
+@cindex fast tracepoints
+Some targets may support @dfn{fast tracepoints}, which are inserted in
+a different way (such as with a jump instead of a trap), that is
+faster but possibly restricted in where they may be installed.
+
This section describes commands to set tracepoints and associated
conditions and actions.
* Create and Delete Tracepoints::
* Enable and Disable Tracepoints::
* Tracepoint Passcounts::
+* Tracepoint Conditions::
+* Trace State Variables::
* Tracepoint Actions::
* Listing Tracepoints::
* Starting and Stopping Trace Experiments::
@table @code
@cindex set tracepoint
@kindex trace
-@item trace
+@item trace @var{location}
The @code{trace} command is very similar to the @code{break} command.
-Its argument can be a source line, a function name, or an address in
-the target program. @xref{Set Breaks}. The @code{trace} command
-defines a tracepoint, which is a point in the target program where the
-debugger will briefly stop, collect some data, and then allow the
-program to continue. Setting a tracepoint or changing its commands
-doesn't take effect until the next @code{tstart} command; thus, you
-cannot change the tracepoint attributes once a trace experiment is
-running.
+Its argument @var{location} can be a source line, a function name, or
+an address in the target program. @xref{Specify Location}. The
+@code{trace} command defines a tracepoint, which is a point in the
+target program where the debugger will briefly stop, collect some
+data, and then allow the program to continue. Setting a tracepoint or
+changing its actions doesn't take effect until the next @code{tstart}
+command, and once a trace experiment is running, further changes will
+not have any effect until the next trace experiment starts.
Here are some examples of using the @code{trace} command:
@noindent
You can abbreviate @code{trace} as @code{tr}.
+@item trace @var{location} if @var{cond}
+Set a tracepoint with condition @var{cond}; evaluate the expression
+@var{cond} each time the tracepoint is reached, and collect data only
+if the value is nonzero---that is, if @var{cond} evaluates as true.
+@xref{Tracepoint Conditions, ,Tracepoint Conditions}, for more
+information on tracepoint conditions.
+
+@item ftrace @var{location} [ if @var{cond} ]
+@cindex set fast tracepoint
+@kindex ftrace
+The @code{ftrace} command sets a fast tracepoint. For targets that
+support them, fast tracepoints will use a more efficient but possibly
+less general technique to trigger data collection, such as a jump
+instruction instead of a trap, or some sort of hardware support. It
+may not be possible to create a fast tracepoint at the desired
+location, in which case the command will exit with an explanatory
+message.
+
+@value{GDBN} handles arguments to @code{ftrace} exactly as for
+@code{trace}.
+
@vindex $tpnum
@cindex last tracepoint number
@cindex recent tracepoint number
@cindex tracepoint deletion
@item delete tracepoint @r{[}@var{num}@r{]}
Permanently delete one or more tracepoints. With no argument, the
-default is to delete all tracepoints.
+default is to delete all tracepoints. Note that the regular
+@code{delete} command can remove tracepoints also.
Examples:
@node Enable and Disable Tracepoints
@subsection Enable and Disable Tracepoints
+These commands are deprecated; they are equivalent to plain @code{disable} and @code{enable}.
+
@table @code
@kindex disable tracepoint
@item disable tracepoint @r{[}@var{num}@r{]}
@end smallexample
@end table
+@node Tracepoint Conditions
+@subsection Tracepoint Conditions
+@cindex conditional tracepoints
+@cindex tracepoint conditions
+
+The simplest sort of tracepoint collects data every time your program
+reaches a specified place. You can also specify a @dfn{condition} for
+a tracepoint. A condition is just a Boolean expression in your
+programming language (@pxref{Expressions, ,Expressions}). A
+tracepoint with a condition evaluates the expression each time your
+program reaches it, and data collection happens only if the condition
+is true.
+
+Tracepoint conditions can be specified when a tracepoint is set, by
+using @samp{if} in the arguments to the @code{trace} command.
+@xref{Create and Delete Tracepoints, ,Setting Tracepoints}. They can
+also be set or changed at any time with the @code{condition} command,
+just as with breakpoints.
+
+Unlike breakpoint conditions, @value{GDBN} does not actually evaluate
+the conditional expression itself. Instead, @value{GDBN} encodes the
+expression into an agent expression (@pxref{Agent Expressions}
+suitable for execution on the target, independently of @value{GDBN}.
+Global variables become raw memory locations, locals become stack
+accesses, and so forth.
+
+For instance, suppose you have a function that is usually called
+frequently, but should not be called after an error has occurred. You
+could use the following tracepoint command to collect data about calls
+of that function that happen while the error code is propagating
+through the program; an unconditional tracepoint could end up
+collecting thousands of useless trace frames that you would have to
+search through.
+
+@smallexample
+(@value{GDBP}) @kbd{trace normal_operation if errcode > 0}
+@end smallexample
+
+@node Trace State Variables
+@subsection Trace State Variables
+@cindex trace state variables
+
+A @dfn{trace state variable} is a special type of variable that is
+created and managed by target-side code. The syntax is the same as
+that for GDB's convenience variables (a string prefixed with ``$''),
+but they are stored on the target. They must be created explicitly,
+using a @code{tvariable} command. They are always 64-bit signed
+integers.
+
+Trace state variables are remembered by @value{GDBN}, and downloaded
+to the target along with tracepoint information when the trace
+experiment starts. There are no intrinsic limits on the number of
+trace state variables, beyond memory limitations of the target.
+
+@cindex convenience variables, and trace state variables
+Although trace state variables are managed by the target, you can use
+them in print commands and expressions as if they were convenience
+variables; @value{GDBN} will get the current value from the target
+while the trace experiment is running. Trace state variables share
+the same namespace as other ``$'' variables, which means that you
+cannot have trace state variables with names like @code{$23} or
+@code{$pc}, nor can you have a trace state variable and a convenience
+variable with the same name.
+
+@table @code
+
+@item tvariable $@var{name} [ = @var{expression} ]
+@kindex tvariable
+The @code{tvariable} command creates a new trace state variable named
+@code{$@var{name}}, and optionally gives it an initial value of
+@var{expression}. @var{expression} is evaluated when this command is
+entered; the result will be converted to an integer if possible,
+otherwise @value{GDBN} will report an error. A subsequent
+@code{tvariable} command specifying the same name does not create a
+variable, but instead assigns the supplied initial value to the
+existing variable of that name, overwriting any previous initial
+value. The default initial value is 0.
+
+@item info tvariables
+@kindex info tvariables
+List all the trace state variables along with their initial values.
+Their current values may also be displayed, if the trace experiment is
+currently running.
+
+@item delete tvariable @r{[} $@var{name} @dots{} @r{]}
+@kindex delete tvariable
+Delete the given trace state variables, or all of them if no arguments
+are specified.
+
+@end table
+
@node Tracepoint Actions
@subsection Tracepoint Action Lists
The command @code{info scope} (@pxref{Symbols, info scope}) is
particularly useful for figuring out what data to collect.
+@kindex teval @r{(tracepoints)}
+@item teval @var{expr1}, @var{expr2}, @dots{}
+Evaluate the given expressions when the tracepoint is hit. This
+command accepts a comma-separated list of expressions. The results
+are discarded, so this is mainly useful for assigning values to trace
+state variables (@pxref{Trace State Variables}) without adding those
+values to the trace buffer, as would be the case if the @code{collect}
+action were used.
+
@kindex while-stepping @r{(tracepoints)}
@item while-stepping @var{n}
Perform @var{n} single-step traces after the tracepoint, collecting
@noindent
You may abbreviate @code{while-stepping} as @code{ws} or
@code{stepping}.
+
+@item set default-collect @var{expr1}, @var{expr2}, @dots{}
+@kindex set default-collect
+@cindex default collection action
+This variable is a list of expressions to collect at each tracepoint
+hit. It is effectively an additional @code{collect} action prepended
+to every tracepoint action list. The expressions are parsed
+individually for each tracepoint, so for instance a variable named
+@code{xyz} may be interpreted as a global for one tracepoint, and a
+local for another, as appropriate to the tracepoint's location.
+
+@item show default-collect
+@kindex show default-collect
+Show the list of expressions that are collected by default at each
+tracepoint hit.
+
@end table
@node Listing Tracepoints
@kindex info tp
@cindex information about tracepoints
@item info tracepoints @r{[}@var{num}@r{]}
-Display information about the tracepoint @var{num}. If you don't specify
-a tracepoint number, displays information about all the tracepoints
-defined so far. For each tracepoint, the following information is
-shown:
+Display information about the tracepoint @var{num}. If you don't
+specify a tracepoint number, displays information about all the
+tracepoints defined so far. The format is similar to that used for
+@code{info breakpoints}; in fact, @code{info tracepoints} is the same
+command, simply restricting itself to tracepoints.
+
+A tracepoint's listing may include additional information specific to
+tracing:
@itemize @bullet
@item
-its number
-@item
-whether it is enabled or disabled
-@item
-its address
-@item
its passcount as given by the @code{passcount @var{n}} command
@item
its step count as given by the @code{while-stepping @var{n}} command
@item
-where in the source files is the tracepoint set
-@item
-its action list as given by the @code{actions} command
+its action list as given by the @code{actions} command. The actions
+are prefixed with an @samp{A} so as to distinguish them from commands.
@end itemize
@smallexample
(@value{GDBP}) @b{info trace}
-Num Enb Address PassC StepC What
-1 y 0x002117c4 0 0 <gdb_asm>
-2 y 0x0020dc64 0 0 in g_test at g_test.c:1375
-3 y 0x0020b1f4 0 0 in get_data at ../foo.c:41
+Num Type Disp Enb Address What
+1 tracepoint keep y 0x0804ab57 in foo() at main.cxx:7
+ pass count 1200
+ step count 20
+ A while-stepping 20
+ A collect globfoo, $regs
+ A end
+ A collect globfoo2
+ A end
(@value{GDBP})
@end smallexample
(@value{GDBP}) @b{tstop}
@end smallexample
+@cindex disconnected tracing
+You can choose to continue running the trace experiment even if
+@value{GDBN} disconnects from the target, voluntarily or
+involuntarily. For commands such as @code{detach}, the debugger will
+ask what you want to do with the trace. But for unexpected
+terminations (@value{GDBN} crash, network outage), it would be
+unfortunate to lose hard-won trace data, so the variable
+@code{disconnected-tracing} lets you decide whether the trace should
+continue running without @value{GDBN}.
+
+@table @code
+@item set disconnected-tracing on
+@itemx set disconnected-tracing off
+@kindex set disconnected-tracing
+Choose whether a tracing run should continue to run if @value{GDBN}
+has disconnected from the target. Note that @code{detach} or
+@code{quit} will ask you directly what to do about a running trace no
+matter what this variable's setting, so the variable is mainly useful
+for handling unexpected situations, such as loss of the network.
+
+@item show disconnected-tracing
+@kindex show disconnected-tracing
+Show the current choice for disconnected tracing.
+
+@end table
+
+When you reconnect to the target, the trace experiment may or may not
+still be running; it might have filled the trace buffer in the
+meantime, or stopped for one of the other reasons. If it is running,
+it will continue after reconnection.
+
+Upon reconnection, the target will upload information about the
+tracepoints in effect. @value{GDBN} will then compare that
+information to the set of tracepoints currently defined, and attempt
+to match them up, allowing for the possibility that the numbers may
+have changed due to creation and deletion in the meantime. If one of
+the target's tracepoints does not match any in @value{GDBN}, the
+debugger will create a new tracepoint, so that you have a number with
+which to specify that tracepoint. This matching-up process is
+necessarily heuristic, and it may result in useless tracepoints being
+created; you may simply delete them if they are of no use.
@node Analyze Collected Data
@section Using the Collected Data
Here's a simple example of using these convenience variables for
stepping through all the trace snapshots and printing some of their
-data.
+data. Note that these are not the same as trace state variables,
+which are managed by the target.
@smallexample
(@value{GDBP}) @b{tfind start}
> end
@end smallexample
+@node Trace Files
+@section Using Trace Files
+@cindex trace files
+
+In some situations, the target running a trace experiment may no
+longer be available; perhaps it crashed, or the hardware was needed
+for a different activity. To handle these cases, you can arrange to
+dump the trace data into a file, and later use that file as a source
+of trace data, via the @code{target tfile} command.
+
+@table @code
+
+@kindex tsave
+@item tsave [ -r ] @var{filename}
+Save the trace data to @var{filename}. By default, this command
+assumes that @var{filename} refers to the host filesystem, so if
+necessary @value{GDBN} will copy raw trace data up from the target and
+then save it. If the target supports it, you can also supply the
+optional argument @code{-r} (``remote'') to direct the target to save
+the data directly into @var{filename} in its own filesystem, which may be
+more efficient if the trace buffer is very large. (Note, however, that
+@code{target tfile} can only read from files accessible to the host.)
+
+@kindex target tfile
+@kindex tfile
+@item target tfile @var{filename}
+Use the file named @var{filename} as a source of trace data. Commands
+that examine data work as they do with a live target, but it is not
+possible to run any new trace experiments. @code{tstatus} will report
+the state of the trace run at the moment the data was saved, as well
+as the current trace frame you are examining. @var{filename} must be
+on a filesystem accessible to the host.
+
+@end table
+
@node Overlays
@chapter Debugging Programs That Use Overlays
@cindex overlays
There are two encodings in use, depending on the architecture: BID (Binary
Integer Decimal) for x86 and x86-64, and DPD (Densely Packed Decimal) for
-PowerPC. @value{GDBN} will use the appropriate encoding for the configured
+PowerPC. @value{GDBN} will use the appropriate encoding for the configured
target.
Because of a limitation in @file{libdecnumber}, the library used by @value{GDBN}
underflow, overflow and divide by zero exceptions.
In the PowerPC architecture, @value{GDBN} provides a set of pseudo-registers
-to inspect @code{_Decimal128} values stored in floating point registers. See
-@ref{PowerPC,,PowerPC} for more details.
+to inspect @code{_Decimal128} values stored in floating point registers.
+See @ref{PowerPC,,PowerPC} for more details.
@node Objective-C
@subsection Objective-C
@table @code
@item **
-The exponentiation operator. It raises the first operand to the power
+The exponentiation operator. It raises the first operand to the power
of the second one.
@item :
precedence as @code{*}.
@item -
-Negative. Defined on @code{INTEGER} and @code{REAL} data.
+Negative. Defined on @code{INTEGER} and @code{REAL} data.
@item ^
Pointer dereferencing. Defined on pointer types.
1 8088000 0 15 Child Activation Wait main_task
2 80a4000 1 15 Accept Statement b
3 809a800 1 15 Child Activation Wait a
-* 4 80ae800 3 15 Running c
+* 4 80ae800 3 15 Runnable c
@end smallexample
The task has been created but has not been activated. It cannot be
executing.
-@item Running
-The task currently running.
-
@item Runnable
The task is not blocked for any reason known to Ada. (It may be waiting
for a mutex, though.) It is conceptually "executing" in normal mode.
(@value{GDBP}) info tasks
ID TID P-ID Pri State Name
1 8077880 0 15 Child Activation Wait main_task
-* 2 807c468 1 15 Running task_1
+* 2 807c468 1 15 Runnable task_1
(@value{GDBP}) info task 2
Ada Task: 0x807c468
Name: task_1
(@value{GDBP}) info tasks
ID TID P-ID Pri State Name
1 8077870 0 15 Child Activation Wait main_task
-* 2 807c458 1 15 Running t
+* 2 807c458 1 15 Runnable t
(@value{GDBP}) task
[Current task is 2]
@end smallexample
(@value{GDBP}) info tasks
ID TID P-ID Pri State Name
1 8077870 0 15 Child Activation Wait main_task
-* 2 807c458 1 15 Running t
+* 2 807c458 1 15 Runnable t
(@value{GDBP}) task 1
[Switching to task 1]
#0 0x8067726 in pthread_cond_wait ()
#4 0x804aacc in un () at un.adb:5
@end smallexample
+@item break @var{linespec} task @var{taskno}
+@itemx break @var{linespec} task @var{taskno} if @dots{}
+@cindex breakpoints and tasks, in Ada
+@cindex task breakpoints, in Ada
+@kindex break @dots{} task @var{taskno}@r{ (Ada)}
+These commands are like the @code{break @dots{} thread @dots{}}
+command (@pxref{Thread Stops}).
+@var{linespec} specifies source lines, as described
+in @ref{Specify Location}.
+
+Use the qualifier @samp{task @var{taskno}} with a breakpoint command
+to specify that you only want @value{GDBN} to stop the program when a
+particular Ada task reaches this breakpoint. @var{taskno} is one of the
+numeric task identifiers assigned by @value{GDBN}, shown in the first
+column of the @samp{info tasks} display.
+
+If you do not specify @samp{task @var{taskno}} when you set a
+breakpoint, the breakpoint applies to @emph{all} tasks of your
+program.
+
+You can use the @code{task} qualifier on conditional breakpoints as
+well; in this case, place @samp{task @var{taskno}} before the
+breakpoint condition (before the @code{if}).
+
+For example,
+
+@smallexample
+@iftex
+@leftskip=0.5cm
+@end iftex
+(@value{GDBP}) info tasks
+ ID TID P-ID Pri State Name
+ 1 140022020 0 15 Child Activation Wait main_task
+ 2 140045060 1 15 Accept/Select Wait t2
+ 3 140044840 1 15 Runnable t1
+* 4 140056040 1 15 Runnable t3
+(@value{GDBP}) b 15 task 2
+Breakpoint 5 at 0x120044cb0: file test_task_debug.adb, line 15.
+(@value{GDBP}) cont
+Continuing.
+task # 1 running
+task # 2 running
+
+Breakpoint 5, test_task_debug () at test_task_debug.adb:15
+15 flush;
+(@value{GDBP}) info tasks
+ ID TID P-ID Pri State Name
+ 1 140022020 0 15 Child Activation Wait main_task
+* 2 140045060 1 15 Runnable t2
+ 3 140044840 1 15 Runnable t1
+ 4 140056040 1 15 Delay Sleep t3
+@end smallexample
@end table
@node Ada Tasks and Core Files
@code{Standard} explicitly.
@end itemize
+Older versions of the compiler sometimes generate erroneous debugging
+information, resulting in the debugger incorrectly printing the value
+of affected entities. In some cases, the debugger is able to work
+around an issue automatically. In other cases, the debugger is able
+to work around the issue, but the work-around has to be specifically
+enabled.
+
+@kindex set ada trust-PAD-over-XVS
+@kindex show ada trust-PAD-over-XVS
+@table @code
+
+@item set ada trust-PAD-over-XVS on
+Configure GDB to strictly follow the GNAT encoding when computing the
+value of Ada entities, particularly when @code{PAD} and @code{PAD___XVS}
+types are involved (see @code{ada/exp_dbug.ads} in the GCC sources for
+a complete description of the encoding used by the GNAT compiler).
+This is the default.
+
+@item set ada trust-PAD-over-XVS off
+This is related to the encoding using by the GNAT compiler. If @value{GDBN}
+sometimes prints the wrong value for certain entities, changing @code{ada
+trust-PAD-over-XVS} to @code{off} activates a work-around which may fix
+the issue. It is always safe to set @code{ada trust-PAD-over-XVS} to
+@code{off}, but this incurs a slight performance penalty, so it is
+recommended to leave this setting to @code{on} unless necessary.
+
+@end table
+
@node Unsupported Languages
@section Unsupported Languages
@kindex info variables
@item info variables
-Print the names and data types of all variables that are declared
+Print the names and data types of all variables that are defined
outside of functions (i.e.@: excluding local variables).
@item info variables @var{regexp}
@item show opaque-type-resolution
Show whether opaque types are resolved or not.
-@kindex set print symbol-loading
-@cindex print messages when symbols are loaded
-@item set print symbol-loading
-@itemx set print symbol-loading on
-@itemx set print symbol-loading off
-The @code{set print symbol-loading} command allows you to enable or
-disable printing of messages when @value{GDBN} loads symbols.
-By default, these messages will be printed, and normally this is what
-you want. Disabling these messages is useful when debugging applications
-with lots of shared libraries where the quantity of output can be more
-annoying than useful.
-
-@kindex show print symbol-loading
-@item show print symbol-loading
-Show whether messages will be printed when @value{GDBN} loads symbols.
-
@kindex maint print symbols
@cindex symbol dump
@kindex maint print psymbols
the function, or if you passed it incorrect arguments). What happens
in that case is controlled by the @code{set unwindonsignal} command.
+Similarly, with a C@t{++} program it is possible for the function you
+call via the @code{print} or @code{call} command to generate an
+exception that is not handled due to the constraints of the dummy
+frame. In this case, any exception that is raised in the frame, but has
+an out-of-frame exception handler will not be found. GDB builds a
+dummy-frame for the inferior function call, and the unwinder cannot
+seek for exception handlers outside of this dummy-frame. What happens
+in that case is controlled by the
+@code{set unwind-on-terminating-exception} command.
+
@table @code
@item set unwindonsignal
@kindex set unwindonsignal
@kindex show unwindonsignal
Show the current setting of stack unwinding in the functions called by
@value{GDBN}.
+
+@item set unwind-on-terminating-exception
+@kindex set unwind-on-terminating-exception
+@cindex unwind stack in called functions with unhandled exceptions
+@cindex call dummy stack unwinding on unhandled exception.
+Set unwinding of the stack if a C@t{++} exception is raised, but left
+unhandled while in a function that @value{GDBN} called in the program being
+debugged. If set to on (the default), @value{GDBN} unwinds the stack
+it created for the call and restores the context to what it was before
+the call. If set to off, @value{GDBN} the exception is delivered to
+the default C@t{++} exception handler and the inferior terminated.
+
+@item show unwind-on-terminating-exception
+@kindex show unwind-on-terminating-exception
+Show the current setting of stack unwinding in the functions called by
+@value{GDBN}.
+
@end table
@cindex weak alias functions
* Files:: Commands to specify files
* Separate Debug Files:: Debugging information in separate files
* Symbol Errors:: Errors reading symbol files
+* Data Files:: GDB data files
@end menu
@node Files
@kindex readnow
@cindex reading symbols immediately
@cindex symbols, reading immediately
-@item symbol-file @var{filename} @r{[} -readnow @r{]}
-@itemx file @var{filename} @r{[} -readnow @r{]}
+@item symbol-file @r{[} -readnow @r{]} @var{filename}
+@itemx file @r{[} -readnow @r{]} @var{filename}
You can override the @value{GDBN} two-stage strategy for reading symbol
tables by using the @samp{-readnow} option with any of the commands that
load symbol table information, if you want to be sure @value{GDBN} has the
@table @code
@kindex info sharedlibrary
@kindex info share
-@item info share
-@itemx info sharedlibrary
-Print the names of the shared libraries which are currently loaded.
+@item info share @var{regex}
+@itemx info sharedlibrary @var{regex}
+Print the names of the shared libraries which are currently loaded
+that match @var{regex}. If @var{regex} is omitted then print
+all shared libraries that are loaded.
@kindex sharedlibrary
@kindex share
usually @file{@var{executable}.debug}, where @var{executable} is the
name of the corresponding executable file without leading directories
(e.g., @file{ls.debug} for @file{/usr/bin/ls}). In addition, the
-debug link specifies a CRC32 checksum for the debug file, which
-@value{GDBN} uses to validate that the executable and the debug file
-came from the same build.
+debug link specifies a 32-bit @dfn{Cyclic Redundancy Check} (CRC)
+checksum for the debug file, which @value{GDBN} uses to validate that
+the executable and the debug file came from the same build.
@item
The executable contains a @dfn{build ID}, a unique bit string that is
@table @code
@kindex set debug-file-directory
-@item set debug-file-directory @var{directory}
-Set the directory which @value{GDBN} searches for separate debugging
-information files to @var{directory}.
+@item set debug-file-directory @var{directories}
+Set the directories which @value{GDBN} searches for separate debugging
+information files to @var{directory}. Multiple directory components can be set
+concatenating them by a directory separator.
@kindex show debug-file-directory
@item show debug-file-directory
-Show the directory @value{GDBN} searches for separate debugging
+Show the directories @value{GDBN} searches for separate debugging
information files.
@end table
@noindent
-Since there are many different ways to compute CRC's for the debug
-link (different polynomials, reversals, byte ordering, etc.), the
-simplest way to describe the CRC used in @code{.gnu_debuglink}
-sections is to give the complete code for a function that computes it:
+@cindex CRC algorithm definition
+The CRC used in @code{.gnu_debuglink} is the CRC-32 defined in
+IEEE 802.3 using the polynomial:
+
+@c TexInfo requires naked braces for multi-digit exponents for Tex
+@c output, but this causes HTML output to barf. HTML has to be set using
+@c raw commands. So we end up having to specify this equation in 2
+@c different ways!
+@ifhtml
+@display
+@html
+ <em>x</em><sup>32</sup> + <em>x</em><sup>26</sup> + <em>x</em><sup>23</sup> + <em>x</em><sup>22</sup> + <em>x</em><sup>16</sup> + <em>x</em><sup>12</sup> + <em>x</em><sup>11</sup>
+ + <em>x</em><sup>10</sup> + <em>x</em><sup>8</sup> + <em>x</em><sup>7</sup> + <em>x</em><sup>5</sup> + <em>x</em><sup>4</sup> + <em>x</em><sup>2</sup> + <em>x</em> + 1
+@end html
+@end display
+@end ifhtml
+@ifnothtml
+@display
+ @math{x^{32} + x^{26} + x^{23} + x^{22} + x^{16} + x^{12} + x^{11}}
+ @math{+ x^{10} + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1}
+@end display
+@end ifnothtml
+
+The function is computed byte at a time, taking the least
+significant bit of each byte first. The initial pattern
+@code{0xffffffff} is used, to ensure leading zeros affect the CRC and
+the final result is inverted to ensure trailing zeros also affect the
+CRC.
+
+@emph{Note:} This is the same CRC polynomial as used in handling the
+@dfn{Remote Serial Protocol} @code{qCRC} packet (@pxref{Remote Protocol,
+, @value{GDBN} Remote Serial Protocol}). However in the
+case of the Remote Serial Protocol, the CRC is computed @emph{most}
+significant bit first, and the result is not inverted, so trailing
+zeros have no effect on the CRC value.
+
+To complete the description, we show below the code of the function
+which produces the CRC used in @code{.gnu_debuglink}. Inverting the
+initially supplied @code{crc} argument means that an initial call to
+this function passing in zero will start computing the CRC using
+@code{0xffffffff}.
@kindex gnu_debuglink_crc32
@smallexample
@end table
+@node Data Files
+@section GDB Data Files
+
+@cindex prefix for data files
+@value{GDBN} will sometimes read an auxiliary data file. These files
+are kept in a directory known as the @dfn{data directory}.
+
+You can set the data directory's name, and view the name @value{GDBN}
+is currently using.
+
+@table @code
+@kindex set data-directory
+@item set data-directory @var{directory}
+Set the directory which @value{GDBN} searches for auxiliary data files
+to @var{directory}.
+
+@kindex show data-directory
+@item show data-directory
+Show the directory @value{GDBN} searches for auxiliary data files.
+@end table
+
+@cindex default data directory
+@cindex @samp{--with-gdb-datadir}
+You can set the default data directory by using the configure-time
+@samp{--with-gdb-datadir} option. If the data directory is inside
+@value{GDBN}'s configured binary prefix (set with @samp{--prefix} or
+@samp{--exec-prefix}), then the default data directory will be updated
+automatically if the installed @value{GDBN} is moved to a new
+location.
+
@node Targets
@chapter Specifying a Debugging Target
Disable or enable specific debugging messages associated with the remote
protocol (@pxref{Remote Protocol}).
+@item monitor set libthread-db-search-path [PATH]
+@cindex gdbserver, search path for @code{libthread_db}
+When this command is issued, @var{path} is a colon-separated list of
+directories to search for @code{libthread_db} (@pxref{Threads,,set
+libthread-db-search-path}). If you omit @var{path},
+@samp{libthread-db-search-path} will be reset to an empty list.
+
@item monitor exit
Tell gdbserver to exit immediately. This command should be followed by
@code{disconnect} to close the debugging session. @code{gdbserver} will
target system. If it is not set, the target will use a default
filename (e.g.@: the last program run).
+@item set remote interrupt-sequence
+@cindex interrupt remote programs
+@cindex select Ctrl-C, BREAK or BREAK-g
+Allow the user to select one of @samp{Ctrl-C}, a @code{BREAK} or
+@samp{BREAK-g} as the
+sequence to the remote target in order to interrupt the execution.
+@samp{Ctrl-C} is a default. Some system prefers @code{BREAK} which
+is high level of serial line for some certain time.
+Linux kernel prefers @samp{BREAK-g}, a.k.a Magic SysRq g.
+It is @code{BREAK} signal followed by character @code{g}.
+
+@item show interrupt-sequence
+Show which of @samp{Ctrl-C}, @code{BREAK} or @code{BREAK-g}
+is sent by @value{GDBN} to interrupt the remote program.
+@code{BREAK-g} is BREAK signal followed by @code{g} and
+also known as Magic SysRq g.
+
+@item set remote interrupt-on-connect
+@cindex send interrupt-sequence on start
+Specify whether interrupt-sequence is sent to remote target when
+@value{GDBN} connects to it. This is mostly needed when you debug
+Linux kernel. Linux kernel expects @code{BREAK} followed by @code{g}
+which is known as Magic SysRq g in order to connect @value{GDBN}.
+
+@item show interrupt-on-connect
+Show whether interrupt-sequence is sent
+to remote target when @value{GDBN} connects to it.
+
@kindex set tcp
@kindex show tcp
@item set tcp auto-retry on
@tab @code{qXfer:siginfo:write}
@tab @code{set $_siginfo}
+@item @code{threads}
+@tab @code{qXfer:threads:read}
+@tab @code{info threads}
+
@item @code{get-thread-local-@*storage-address}
@tab @code{qGetTLSAddr}
@tab Displaying @code{__thread} variables
@cindex Cygwin-specific commands
@value{GDBN} supports native debugging of MS Windows programs, including
-DLLs with and without symbolic debugging information. There are various
-additional Cygwin-specific commands, described in this section.
-Working with DLLs that have no debugging symbols is described in
-@ref{Non-debug DLL Symbols}.
+DLLs with and without symbolic debugging information.
+
+@cindex Ctrl-BREAK, MS-Windows
+@cindex interrupt debuggee on MS-Windows
+MS-Windows programs that call @code{SetConsoleMode} to switch off the
+special meaning of the @samp{Ctrl-C} keystroke cannot be interrupted
+by typing @kbd{C-c}. For this reason, @value{GDBN} on MS-Windows
+supports @kbd{C-@key{BREAK}} as an alternative interrupt key
+sequence, which can be used to interrupt the debuggee even if it
+ignores @kbd{C-c}.
+
+There are various additional Cygwin-specific commands, described in
+this section. Working with DLLs that have no debugging symbols is
+described in @ref{Non-debug DLL Symbols}.
@table @code
@kindex info w32
tools, DLL export symbols are made available with a prefix based on the
DLL name, for instance @code{KERNEL32!CreateFileA}. The plain name is
also entered into the symbol table, so @code{CreateFileA} is often
-sufficient. In some cases there will be name clashes within a program
+sufficient. In some cases there will be name clashes within a program
(particularly if the executable itself includes full debugging symbols)
necessitating the use of the fully qualified name when referring to the
-contents of the DLL. Use single-quotes around the name to avoid the
+contents of the DLL. Use single-quotes around the name to avoid the
exclamation mark (``!'') being interpreted as a language operator.
Note that the internal name of the DLL may be all upper-case, even
-though the file name of the DLL is lower-case, or vice-versa. Since
+though the file name of the DLL is lower-case, or vice-versa. Since
symbols within @value{GDBN} are @emph{case-sensitive} this may cause
some confusion. If in doubt, try the @code{info functions} and
@code{info variables} commands or even @code{maint print msymbols}
* ARM:: ARM RDI
* M32R/D:: Renesas M32R/D
* M68K:: Motorola M68K
+* MicroBlaze:: Xilinx MicroBlaze
* MIPS Embedded:: MIPS Embedded
* OpenRISC 1000:: OpenRisc 1000
* PA:: HP PA Embedded
@end table
+@node MicroBlaze
+@subsection MicroBlaze
+@cindex Xilinx MicroBlaze
+@cindex XMD, Xilinx Microprocessor Debugger
+
+The MicroBlaze is a soft-core processor supported on various Xilinx
+FPGAs, such as Spartan or Virtex series. Boards with these processors
+usually have JTAG ports which connect to a host system running the Xilinx
+Embedded Development Kit (EDK) or Software Development Kit (SDK).
+This host system is used to download the configuration bitstream to
+the target FPGA. The Xilinx Microprocessor Debugger (XMD) program
+communicates with the target board using the JTAG interface and
+presents a @code{gdbserver} interface to the board. By default
+@code{xmd} uses port @code{1234}. (While it is possible to change
+this default port, it requires the use of undocumented @code{xmd}
+commands. Contact Xilinx support if you need to do this.)
+
+Use these GDB commands to connect to the MicroBlaze target processor.
+
+@table @code
+@item target remote :1234
+Use this command to connect to the target if you are running @value{GDBN}
+on the same system as @code{xmd}.
+
+@item target remote @var{xmd-host}:1234
+Use this command to connect to the target if it is connected to @code{xmd}
+running on a different system named @var{xmd-host}.
+
+@item load
+Use this command to download a program to the MicroBlaze target.
+
+@item set debug microblaze @var{n}
+Enable MicroBlaze-specific debugging messages if non-zero.
+
+@item show debug microblaze @var{n}
+Show MicroBlaze-specific debugging level.
+@end table
+
@node MIPS Embedded
@subsection MIPS Embedded
@end table
+When @value{GDBN} is debugging a combined PowerPC/SPU application
+on the Cell Broadband Engine, it provides in addition the following
+special commands:
+
+@table @code
+@item set spu stop-on-load @var{arg}
+@kindex set spu
+Set whether to stop for new SPE threads. When set to @code{on}, @value{GDBN}
+will give control to the user when a new SPE thread enters its @code{main}
+function. The default is @code{off}.
+
+@item show spu stop-on-load
+@kindex show spu
+Show whether to stop for new SPE threads.
+
+@item set spu auto-flush-cache @var{arg}
+Set whether to automatically flush the software-managed cache. When set to
+@code{on}, @value{GDBN} will automatically cause the SPE software-managed
+cache to be flushed whenever SPE execution stops. This provides a consistent
+view of PowerPC memory that is accessed via the cache. If an application
+does not use the software-managed cache, this option has no effect.
+
+@item show spu auto-flush-cache
+Show whether to automatically flush the software-managed cache.
+
+@end table
+
@node PowerPC
@subsection PowerPC
@cindex PowerPC architecture
* ABI:: Configuring the current ABI
* Messages/Warnings:: Optional warnings and messages
* Debugging Output:: Optional messages about internal happenings
+* Other Misc Settings:: Other Miscellaneous Settings
@end menu
@node Prompt
@end table
+@anchor{confirmation requests}
By default, @value{GDBN} is cautious, and asks what sometimes seems to be a
lot of stupid questions to confirm certain commands. For example, if
you try to run a program which is already running:
@item show debug frame
Displays the current state of displaying @value{GDBN} frame debugging
info.
+@item set debug gnu-nat
+@cindex @sc{gnu}/Hurd debug messages
+Turns on or off debugging messages from the @sc{gnu}/Hurd debug support.
+@item show debug gnu-nat
+Show the current state of @sc{gnu}/Hurd debugging messages.
@item set debug infrun
@cindex inferior debugging info
Turns on or off display of @value{GDBN} debugging info for running the inferior.
Displays the current state of XML debugging messages.
@end table
+@node Other Misc Settings
+@section Other Miscellaneous Settings
+@cindex miscellaneous settings
+
+@table @code
+@kindex set interactive-mode
+@item set interactive-mode
+If @code{on}, forces @value{GDBN} to operate interactively.
+If @code{off}, forces @value{GDBN} to operate non-interactively,
+If @code{auto} (the default), @value{GDBN} guesses which mode to use,
+based on whether the debugger was started in a terminal or not.
+
+In the vast majority of cases, the debugger should be able to guess
+correctly which mode should be used. But this setting can be useful
+in certain specific cases, such as running a MinGW @value{GDBN}
+inside a cygwin window.
+
+@kindex show interactive-mode
+@item show interactive-mode
+Displays whether the debugger is operating in interactive mode or not.
+@end table
+
@node Extending GDB
@chapter Extending @value{GDBN}
@cindex extending GDB
on composition of @value{GDBN} commands, and the second is based on the
Python scripting language.
+To facilitate the use of these extensions, @value{GDBN} is capable
+of evaluating the contents of a file. When doing so, @value{GDBN}
+can recognize which scripting language is being used by looking at
+the filename extension. Files with an unrecognized filename extension
+are always treated as a @value{GDBN} Command Files.
+@xref{Command Files,, Command files}.
+
+You can control how @value{GDBN} evaluates these files with the following
+setting:
+
+@table @code
+@kindex set script-extension
+@kindex show script-extension
+@item set script-extension off
+All scripts are always evaluated as @value{GDBN} Command Files.
+
+@item set script-extension soft
+The debugger determines the scripting language based on filename
+extension. If this scripting language is supported, @value{GDBN}
+evaluates the script using that language. Otherwise, it evaluates
+the file as a @value{GDBN} Command File.
+
+@item set script-extension strict
+The debugger determines the scripting language based on filename
+extension, and evaluates the script using that language. If the
+language is not supported, then the evaluation fails.
+
+@item show script-extension
+Display the current value of the @code{script-extension} option.
+
+@end table
+
@menu
* Sequences:: Canned Sequences of Commands
* Python:: Scripting @value{GDBN} using Python
terminal.
You can request the execution of a command file with the @code{source}
-command:
+command. Note that the @code{source} command is also used to evaluate
+scripts that are not Command Files. The exact behavior can be configured
+using the @code{script-extension} setting.
+@xref{Extending GDB,, Extending GDB}.
@table @code
@kindex source
disabled.
@end table
+It is also possible to execute a Python script from the @value{GDBN}
+interpreter:
+
+@table @code
+@item source @file{script-name}
+The script name must end with @samp{.py} and @value{GDBN} must be configured
+to recognize the script language based on filename extension using
+the @code{script-extension} setting. @xref{Extending GDB, ,Extending GDB}.
+
+@item python execfile ("script-name")
+This method is based on the @code{execfile} Python built-in function,
+and thus is always available.
+@end table
+
@node Python API
@subsection Python API
@cindex python api
@menu
* Basic Python:: Basic Python Functions.
* Exception Handling::
+* Auto-loading:: Automatically loading Python code.
* Values From Inferior::
+* Types In Python:: Python representation of types.
+* Pretty Printing:: Pretty-printing values.
+* Selecting Pretty-Printers:: How GDB chooses a pretty-printer.
* Commands In Python:: Implementing new commands in Python.
+* Functions In Python:: Writing new convenience functions.
+* Objfiles In Python:: Object files.
+* Frames In Python:: Acessing inferior stack frames from Python.
+* Lazy Strings In Python:: Python representation of lazy strings.
@end menu
@node Basic Python
It must be a boolean value. If omitted, it defaults to @code{False}.
@end defun
-@findex gdb.get_parameter
-@defun get_parameter parameter
+@findex gdb.parameter
+@defun parameter parameter
Return the value of a @value{GDBN} parameter. @var{parameter} is a
string naming the parameter to look up; @var{parameter} may contain
spaces if the parameter has a multi-part name. For example,
@code{gdb.Value} (@pxref{Values From Inferior}).
@end defun
+@findex gdb.parse_and_eval
+@defun parse_and_eval expression
+Parse @var{expression} as an expression in the current language,
+evaluate it, and return the result as a @code{gdb.Value}.
+@var{expression} must be a string.
+
+This function can be useful when implementing a new command
+(@pxref{Commands In Python}), as it provides a way to parse the
+command's argument as an expression. It is also useful simply to
+compute values, for example, it is the only way to get the value of a
+convenience variable (@pxref{Convenience Vars}) as a @code{gdb.Value}.
+@end defun
+
@findex gdb.write
@defun write string
Print a string to @value{GDBN}'s paginated standard output stream.
Python statement closest to where the @value{GDBN} error occured as the
traceback.
+@node Auto-loading
+@subsubsection Auto-loading
+@cindex auto-loading, Python
+
+When a new object file is read (for example, due to the @code{file}
+command, or because the inferior has loaded a shared library),
+@value{GDBN} will look for a file named @file{@var{objfile}-gdb.py},
+where @var{objfile} is the object file's real name, formed by ensuring
+that the file name is absolute, following all symlinks, and resolving
+@code{.} and @code{..} components. If this file exists and is
+readable, @value{GDBN} will evaluate it as a Python script.
+
+If this file does not exist, and if the parameter
+@code{debug-file-directory} is set (@pxref{Separate Debug Files}),
+then @value{GDBN} will use for its each separated directory component
+@code{component} the file named @file{@code{component}/@var{real-name}}, where
+@var{real-name} is the object file's real name, as described above.
+
+Finally, if this file does not exist, then @value{GDBN} will look for
+a file named @file{@var{data-directory}/python/auto-load/@var{real-name}}, where
+@var{data-directory} is @value{GDBN}'s data directory (available via
+@code{show data-directory}, @pxref{Data Files}), and @var{real-name}
+is the object file's real name, as described above.
+
+When reading an auto-loaded file, @value{GDBN} sets the ``current
+objfile''. This is available via the @code{gdb.current_objfile}
+function (@pxref{Objfiles In Python}). This can be useful for
+registering objfile-specific pretty-printers.
+
+The auto-loading feature is useful for supplying application-specific
+debugging commands and scripts. You can enable or disable this
+feature, and view its current state.
+
+@table @code
+@kindex maint set python auto-load
+@item maint set python auto-load [yes|no]
+Enable or disable the Python auto-loading feature.
+
+@kindex show python auto-load
+@item show python auto-load
+Show whether Python auto-loading is enabled or disabled.
+@end table
+
+@value{GDBN} does not track which files it has already auto-loaded.
+So, your @samp{-gdb.py} file should take care to ensure that it may be
+evaluated multiple times without error.
+
@node Values From Inferior
@subsubsection Values From Inferior
@cindex values from inferior, with Python
Again, @code{bar} will also be a @code{gdb.Value} object.
-For pointer data types, @code{gdb.Value} provides a method for
-dereferencing the pointer to obtain the object it points to.
+The following attributes are provided:
+
+@table @code
+@defivar Value address
+If this object is addressable, this read-only attribute holds a
+@code{gdb.Value} object representing the address. Otherwise,
+this attribute holds @code{None}.
+@end defivar
+
+@cindex optimized out value in Python
+@defivar Value is_optimized_out
+This read-only boolean attribute is true if the compiler optimized out
+this value, thus it is not available for fetching from the inferior.
+@end defivar
+
+@defivar Value type
+The type of this @code{gdb.Value}. The value of this attribute is a
+@code{gdb.Type} object.
+@end defivar
+@end table
+
+The following methods are provided:
+
+@table @code
+@defmethod Value cast type
+Return a new instance of @code{gdb.Value} that is the result of
+casting this instance to the type described by @var{type}, which must
+be a @code{gdb.Type} object. If the cast cannot be performed for some
+reason, this method throws an exception.
+@end defmethod
@defmethod Value dereference
-This method returns a new @code{gdb.Value} object whose contents is
-the object pointed to by the pointer. For example, if @code{foo} is
-a C pointer to an @code{int}, declared in your C program as
+For pointer data types, this method returns a new @code{gdb.Value} object
+whose contents is the object pointed to by the pointer. For example, if
+@code{foo} is a C pointer to an @code{int}, declared in your C program as
@smallexample
int *foo;
value pointed to by @code{foo}.
@end defmethod
-@defmethod Value string @r{[}encoding @r{[}errors@r{]}@r{]}
+@defmethod Value string @r{[}encoding@r{]} @r{[}errors@r{]} @r{[}length@r{]}
If this @code{gdb.Value} represents a string, then this method
converts the contents to a Python string. Otherwise, this method will
throw an exception.
For C-like languages, a value is a string if it is a pointer to or an
array of characters or ints. The string is assumed to be terminated
-by a zero of the appropriate width.
+by a zero of the appropriate width. However if the optional length
+argument is given, the string will be converted to that given length,
+ignoring any embedded zeros that the string may contain.
If the optional @var{encoding} argument is given, it must be a string
naming the encoding of the string in the @code{gdb.Value}, such as
The optional @var{errors} argument is the same as the corresponding
argument to Python's @code{string.decode} method.
+
+If the optional @var{length} argument is given, the string will be
+fetched and converted to the given length.
@end defmethod
-@node Commands In Python
-@subsubsection Commands In Python
+@defmethod Value lazy_string @r{[}encoding@r{]} @r{[}length@r{]}
+If this @code{gdb.Value} represents a string, then this method
+converts the contents to a @code{gdb.LazyString} (@pxref{Lazy Strings
+In Python}). Otherwise, this method will throw an exception.
-@cindex commands in python
-@cindex python commands
-You can implement new @value{GDBN} CLI commands in Python. A CLI
-command is implemented using an instance of the @code{gdb.Command}
-class, most commonly using a subclass.
+If the optional @var{encoding} argument is given, it must be a string
+naming the encoding of the @code{gdb.LazyString}. Some examples are:
+@samp{ascii}, @samp{iso-8859-6} or @samp{utf-8}. If the
+@var{encoding} argument is an encoding that @value{GDBN} does
+recognize, @value{GDBN} will raise an error.
+
+When a lazy string is printed, the @value{GDBN} encoding machinery is
+used to convert the string during printing. If the optional
+@var{encoding} argument is not provided, or is an empty string,
+@value{GDBN} will automatically select the encoding most suitable for
+the string type. For further information on encoding in @value{GDBN}
+please see @ref{Character Sets}.
+
+If the optional @var{length} argument is given, the string will be
+fetched and encoded to the length of characters specified. If
+the @var{length} argument is not provided, the string will be fetched
+and encoded until a null of appropriate width is found.
+@end defmethod
+@end table
-@defmethod Command __init__ name @var{command-class} @r{[}@var{completer-class} @var{prefix}@r{]}
-The object initializer for @code{Command} registers the new command
-with @value{GDBN}. This initializer is normally invoked from the
-subclass' own @code{__init__} method.
+@node Types In Python
+@subsubsection Types In Python
+@cindex types in Python
+@cindex Python, working with types
-@var{name} is the name of the command. If @var{name} consists of
-multiple words, then the initial words are looked for as prefix
-commands. In this case, if one of the prefix commands does not exist,
-an exception is raised.
+@tindex gdb.Type
+@value{GDBN} represents types from the inferior using the class
+@code{gdb.Type}.
-There is no support for multi-line commands.
+The following type-related functions are available in the @code{gdb}
+module:
-@var{command-class} should be one of the @samp{COMMAND_} constants
-defined below. This argument tells @value{GDBN} how to categorize the
-new command in the help system.
+@findex gdb.lookup_type
+@defun lookup_type name [block]
+This function looks up a type by name. @var{name} is the name of the
+type to look up. It must be a string.
-@var{completer-class} is an optional argument. If given, it should be
-one of the @samp{COMPLETE_} constants defined below. This argument
-tells @value{GDBN} how to perform completion for this command. If not
-given, @value{GDBN} will attempt to complete using the object's
-@code{complete} method (see below); if no such method is found, an
-error will occur when completion is attempted.
+Ordinarily, this function will return an instance of @code{gdb.Type}.
+If the named type cannot be found, it will throw an exception.
+@end defun
-@var{prefix} is an optional argument. If @code{True}, then the new
-command is a prefix command; sub-commands of this command may be
-registered.
+An instance of @code{Type} has the following attributes:
-The help text for the new command is taken from the Python
-documentation string for the command's class, if there is one. If no
-documentation string is provided, the default value ``This command is
-not documented.'' is used.
+@table @code
+@defivar Type code
+The type code for this type. The type code will be one of the
+@code{TYPE_CODE_} constants defined below.
+@end defivar
+
+@defivar Type sizeof
+The size of this type, in target @code{char} units. Usually, a
+target's @code{char} type will be an 8-bit byte. However, on some
+unusual platforms, this type may have a different size.
+@end defivar
+
+@defivar Type tag
+The tag name for this type. The tag name is the name after
+@code{struct}, @code{union}, or @code{enum} in C and C@t{++}; not all
+languages have this concept. If this type has no tag name, then
+@code{None} is returned.
+@end defivar
+@end table
+
+The following methods are provided:
+
+@table @code
+@defmethod Type fields
+For structure and union types, this method returns the fields. Range
+types have two fields, the minimum and maximum values. Enum types
+have one field per enum constant. Function and method types have one
+field per parameter. The base types of C@t{++} classes are also
+represented as fields. If the type has no fields, or does not fit
+into one of these categories, an empty sequence will be returned.
+
+Each field is an object, with some pre-defined attributes:
+@table @code
+@item bitpos
+This attribute is not available for @code{static} fields (as in
+C@t{++} or Java). For non-@code{static} fields, the value is the bit
+position of the field.
+
+@item name
+The name of the field, or @code{None} for anonymous fields.
+
+@item artificial
+This is @code{True} if the field is artificial, usually meaning that
+it was provided by the compiler and not the user. This attribute is
+always provided, and is @code{False} if the field is not artificial.
+
+@item is_base_class
+This is @code{True} if the field represents a base class of a C@t{++}
+structure. This attribute is always provided, and is @code{False}
+if the field is not a base class of the type that is the argument of
+@code{fields}, or if that type was not a C@t{++} class.
+
+@item bitsize
+If the field is packed, or is a bitfield, then this will have a
+non-zero value, which is the size of the field in bits. Otherwise,
+this will be zero; in this case the field's size is given by its type.
+
+@item type
+The type of the field. This is usually an instance of @code{Type},
+but it can be @code{None} in some situations.
+@end table
@end defmethod
-@cindex don't repeat Python command
-@defmethod Command dont_repeat
-By default, a @value{GDBN} command is repeated when the user enters a
-blank line at the command prompt. A command can suppress this
-behavior by invoking the @code{dont_repeat} method. This is similar
-to the user command @code{dont-repeat}, see @ref{Define, dont-repeat}.
+@defmethod Type const
+Return a new @code{gdb.Type} object which represents a
+@code{const}-qualified variant of this type.
@end defmethod
-@defmethod Command invoke argument from_tty
-This method is called by @value{GDBN} when this command is invoked.
+@defmethod Type volatile
+Return a new @code{gdb.Type} object which represents a
+@code{volatile}-qualified variant of this type.
+@end defmethod
-@var{argument} is a string. It is the argument to the command, after
-leading and trailing whitespace has been stripped.
+@defmethod Type unqualified
+Return a new @code{gdb.Type} object which represents an unqualified
+variant of this type. That is, the result is neither @code{const} nor
+@code{volatile}.
+@end defmethod
-@var{from_tty} is a boolean argument. When true, this means that the
-command was entered by the user at the terminal; when false it means
-that the command came from elsewhere.
+@defmethod Type range
+Return a Python @code{Tuple} object that contains two elements: the
+low bound of the argument type and the high bound of that type. If
+the type does not have a range, @value{GDBN} will raise a
+@code{RuntimeError} exception.
+@end defmethod
-If this method throws an exception, it is turned into a @value{GDBN}
-@code{error} call. Otherwise, the return value is ignored.
+@defmethod Type reference
+Return a new @code{gdb.Type} object which represents a reference to this
+type.
@end defmethod
-@cindex completion of Python commands
-@defmethod Command complete text word
-This method is called by @value{GDBN} when the user attempts
-completion on this command. All forms of completion are handled by
-this method, that is, the @key{TAB} and @key{M-?} key bindings
-(@pxref{Completion}), and the @code{complete} command (@pxref{Help,
-complete}).
+@defmethod Type pointer
+Return a new @code{gdb.Type} object which represents a pointer to this
+type.
+@end defmethod
-The arguments @var{text} and @var{word} are both strings. @var{text}
-holds the complete command line up to the cursor's location.
-@var{word} holds the last word of the command line; this is computed
-using a word-breaking heuristic.
+@defmethod Type strip_typedefs
+Return a new @code{gdb.Type} that represents the real type,
+after removing all layers of typedefs.
+@end defmethod
-The @code{complete} method can return several values:
-@itemize @bullet
-@item
-If the return value is a sequence, the contents of the sequence are
-used as the completions. It is up to @code{complete} to ensure that the
-contents actually do complete the word. A zero-length sequence is
-allowed, it means that there were no completions available. Only
-string elements of the sequence are used; other elements in the
-sequence are ignored.
+@defmethod Type target
+Return a new @code{gdb.Type} object which represents the target type
+of this type.
-@item
-If the return value is one of the @samp{COMPLETE_} constants defined
-below, then the corresponding @value{GDBN}-internal completion
-function is invoked, and its result is used.
+For a pointer type, the target type is the type of the pointed-to
+object. For an array type (meaning C-like arrays), the target type is
+the type of the elements of the array. For a function or method type,
+the target type is the type of the return value. For a complex type,
+the target type is the type of the elements. For a typedef, the
+target type is the aliased type.
-@item
-All other results are treated as though there were no available
-completions.
-@end itemize
+If the type does not have a target, this method will throw an
+exception.
+@end defmethod
+
+@defmethod Type template_argument n
+If this @code{gdb.Type} is an instantiation of a template, this will
+return a new @code{gdb.Type} which represents the type of the
+@var{n}th template argument.
+
+If this @code{gdb.Type} is not a template type, this will throw an
+exception. Ordinarily, only C@t{++} code will have template types.
+
+@var{name} is searched for globally.
+@end defmethod
+@end table
+
+
+Each type has a code, which indicates what category this type falls
+into. The available type categories are represented by constants
+defined in the @code{gdb} module:
+
+@table @code
+@findex TYPE_CODE_PTR
+@findex gdb.TYPE_CODE_PTR
+@item TYPE_CODE_PTR
+The type is a pointer.
+
+@findex TYPE_CODE_ARRAY
+@findex gdb.TYPE_CODE_ARRAY
+@item TYPE_CODE_ARRAY
+The type is an array.
+
+@findex TYPE_CODE_STRUCT
+@findex gdb.TYPE_CODE_STRUCT
+@item TYPE_CODE_STRUCT
+The type is a structure.
+
+@findex TYPE_CODE_UNION
+@findex gdb.TYPE_CODE_UNION
+@item TYPE_CODE_UNION
+The type is a union.
+
+@findex TYPE_CODE_ENUM
+@findex gdb.TYPE_CODE_ENUM
+@item TYPE_CODE_ENUM
+The type is an enum.
+
+@findex TYPE_CODE_FLAGS
+@findex gdb.TYPE_CODE_FLAGS
+@item TYPE_CODE_FLAGS
+A bit flags type, used for things such as status registers.
+
+@findex TYPE_CODE_FUNC
+@findex gdb.TYPE_CODE_FUNC
+@item TYPE_CODE_FUNC
+The type is a function.
+
+@findex TYPE_CODE_INT
+@findex gdb.TYPE_CODE_INT
+@item TYPE_CODE_INT
+The type is an integer type.
+
+@findex TYPE_CODE_FLT
+@findex gdb.TYPE_CODE_FLT
+@item TYPE_CODE_FLT
+A floating point type.
+
+@findex TYPE_CODE_VOID
+@findex gdb.TYPE_CODE_VOID
+@item TYPE_CODE_VOID
+The special type @code{void}.
+
+@findex TYPE_CODE_SET
+@findex gdb.TYPE_CODE_SET
+@item TYPE_CODE_SET
+A Pascal set type.
+
+@findex TYPE_CODE_RANGE
+@findex gdb.TYPE_CODE_RANGE
+@item TYPE_CODE_RANGE
+A range type, that is, an integer type with bounds.
+
+@findex TYPE_CODE_STRING
+@findex gdb.TYPE_CODE_STRING
+@item TYPE_CODE_STRING
+A string type. Note that this is only used for certain languages with
+language-defined string types; C strings are not represented this way.
+
+@findex TYPE_CODE_BITSTRING
+@findex gdb.TYPE_CODE_BITSTRING
+@item TYPE_CODE_BITSTRING
+A string of bits.
+
+@findex TYPE_CODE_ERROR
+@findex gdb.TYPE_CODE_ERROR
+@item TYPE_CODE_ERROR
+An unknown or erroneous type.
+
+@findex TYPE_CODE_METHOD
+@findex gdb.TYPE_CODE_METHOD
+@item TYPE_CODE_METHOD
+A method type, as found in C@t{++} or Java.
+
+@findex TYPE_CODE_METHODPTR
+@findex gdb.TYPE_CODE_METHODPTR
+@item TYPE_CODE_METHODPTR
+A pointer-to-member-function.
+
+@findex TYPE_CODE_MEMBERPTR
+@findex gdb.TYPE_CODE_MEMBERPTR
+@item TYPE_CODE_MEMBERPTR
+A pointer-to-member.
+
+@findex TYPE_CODE_REF
+@findex gdb.TYPE_CODE_REF
+@item TYPE_CODE_REF
+A reference type.
+
+@findex TYPE_CODE_CHAR
+@findex gdb.TYPE_CODE_CHAR
+@item TYPE_CODE_CHAR
+A character type.
+
+@findex TYPE_CODE_BOOL
+@findex gdb.TYPE_CODE_BOOL
+@item TYPE_CODE_BOOL
+A boolean type.
+
+@findex TYPE_CODE_COMPLEX
+@findex gdb.TYPE_CODE_COMPLEX
+@item TYPE_CODE_COMPLEX
+A complex float type.
+
+@findex TYPE_CODE_TYPEDEF
+@findex gdb.TYPE_CODE_TYPEDEF
+@item TYPE_CODE_TYPEDEF
+A typedef to some other type.
+
+@findex TYPE_CODE_NAMESPACE
+@findex gdb.TYPE_CODE_NAMESPACE
+@item TYPE_CODE_NAMESPACE
+A C@t{++} namespace.
+
+@findex TYPE_CODE_DECFLOAT
+@findex gdb.TYPE_CODE_DECFLOAT
+@item TYPE_CODE_DECFLOAT
+A decimal floating point type.
+
+@findex TYPE_CODE_INTERNAL_FUNCTION
+@findex gdb.TYPE_CODE_INTERNAL_FUNCTION
+@item TYPE_CODE_INTERNAL_FUNCTION
+A function internal to @value{GDBN}. This is the type used to represent
+convenience functions.
+@end table
+
+@node Pretty Printing
+@subsubsection Pretty Printing
+
+@value{GDBN} provides a mechanism to allow pretty-printing of values
+using Python code. The pretty-printer API allows application-specific
+code to greatly simplify the display of complex objects. This
+mechanism works for both MI and the CLI.
+
+For example, here is how a C@t{++} @code{std::string} looks without a
+pretty-printer:
+
+@smallexample
+(@value{GDBP}) print s
+$1 = @{
+ static npos = 4294967295,
+ _M_dataplus = @{
+ <std::allocator<char>> = @{
+ <__gnu_cxx::new_allocator<char>> = @{<No data fields>@}, <No data fields>@},
+ members of std::basic_string<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider:
+ _M_p = 0x804a014 "abcd"
+ @}
+@}
+@end smallexample
+
+After a pretty-printer for @code{std::string} has been installed, only
+the contents are printed:
+
+@smallexample
+(@value{GDBP}) print s
+$2 = "abcd"
+@end smallexample
+
+A pretty-printer is just an object that holds a value and implements a
+specific interface, defined here.
+
+@defop Operation {pretty printer} children (self)
+@value{GDBN} will call this method on a pretty-printer to compute the
+children of the pretty-printer's value.
+
+This method must return an object conforming to the Python iterator
+protocol. Each item returned by the iterator must be a tuple holding
+two elements. The first element is the ``name'' of the child; the
+second element is the child's value. The value can be any Python
+object which is convertible to a @value{GDBN} value.
+
+This method is optional. If it does not exist, @value{GDBN} will act
+as though the value has no children.
+@end defop
+
+@defop Operation {pretty printer} display_hint (self)
+The CLI may call this method and use its result to change the
+formatting of a value. The result will also be supplied to an MI
+consumer as a @samp{displayhint} attribute of the variable being
+printed.
+
+This method is optional. If it does exist, this method must return a
+string.
+
+Some display hints are predefined by @value{GDBN}:
+
+@table @samp
+@item array
+Indicate that the object being printed is ``array-like''. The CLI
+uses this to respect parameters such as @code{set print elements} and
+@code{set print array}.
+
+@item map
+Indicate that the object being printed is ``map-like'', and that the
+children of this value can be assumed to alternate between keys and
+values.
+
+@item string
+Indicate that the object being printed is ``string-like''. If the
+printer's @code{to_string} method returns a Python string of some
+kind, then @value{GDBN} will call its internal language-specific
+string-printing function to format the string. For the CLI this means
+adding quotation marks, possibly escaping some characters, respecting
+@code{set print elements}, and the like.
+@end table
+@end defop
+
+@defop Operation {pretty printer} to_string (self)
+@value{GDBN} will call this method to display the string
+representation of the value passed to the object's constructor.
+
+When printing from the CLI, if the @code{to_string} method exists,
+then @value{GDBN} will prepend its result to the values returned by
+@code{children}. Exactly how this formatting is done is dependent on
+the display hint, and may change as more hints are added. Also,
+depending on the print settings (@pxref{Print Settings}), the CLI may
+print just the result of @code{to_string} in a stack trace, omitting
+the result of @code{children}.
+
+If this method returns a string, it is printed verbatim.
+
+Otherwise, if this method returns an instance of @code{gdb.Value},
+then @value{GDBN} prints this value. This may result in a call to
+another pretty-printer.
+
+If instead the method returns a Python value which is convertible to a
+@code{gdb.Value}, then @value{GDBN} performs the conversion and prints
+the resulting value. Again, this may result in a call to another
+pretty-printer. Python scalars (integers, floats, and booleans) and
+strings are convertible to @code{gdb.Value}; other types are not.
+
+If the result is not one of these types, an exception is raised.
+@end defop
+
+@node Selecting Pretty-Printers
+@subsubsection Selecting Pretty-Printers
+
+The Python list @code{gdb.pretty_printers} contains an array of
+functions that have been registered via addition as a pretty-printer.
+Each @code{gdb.Objfile} also contains a @code{pretty_printers}
+attribute.
+
+A function on one of these lists is passed a single @code{gdb.Value}
+argument and should return a pretty-printer object conforming to the
+interface definition above (@pxref{Pretty Printing}). If a function
+cannot create a pretty-printer for the value, it should return
+@code{None}.
+
+@value{GDBN} first checks the @code{pretty_printers} attribute of each
+@code{gdb.Objfile} and iteratively calls each function in the list for
+that @code{gdb.Objfile} until it receives a pretty-printer object.
+After these lists have been exhausted, it tries the global
+@code{gdb.pretty-printers} list, again calling each function until an
+object is returned.
+
+The order in which the objfiles are searched is not specified. For a
+given list, functions are always invoked from the head of the list,
+and iterated over sequentially until the end of the list, or a printer
+object is returned.
+
+Here is an example showing how a @code{std::string} printer might be
+written:
+
+@smallexample
+class StdStringPrinter:
+ "Print a std::string"
+
+ def __init__ (self, val):
+ self.val = val
+
+ def to_string (self):
+ return self.val['_M_dataplus']['_M_p']
+
+ def display_hint (self):
+ return 'string'
+@end smallexample
+
+And here is an example showing how a lookup function for the printer
+example above might be written.
+
+@smallexample
+def str_lookup_function (val):
+
+ lookup_tag = val.type.tag
+ regex = re.compile ("^std::basic_string<char,.*>$")
+ if lookup_tag == None:
+ return None
+ if regex.match (lookup_tag):
+ return StdStringPrinter (val)
+
+ return None
+@end smallexample
+
+The example lookup function extracts the value's type, and attempts to
+match it to a type that it can pretty-print. If it is a type the
+printer can pretty-print, it will return a printer object. If not, it
+returns @code{None}.
+
+We recommend that you put your core pretty-printers into a Python
+package. If your pretty-printers are for use with a library, we
+further recommend embedding a version number into the package name.
+This practice will enable @value{GDBN} to load multiple versions of
+your pretty-printers at the same time, because they will have
+different names.
+
+You should write auto-loaded code (@pxref{Auto-loading}) such that it
+can be evaluated multiple times without changing its meaning. An
+ideal auto-load file will consist solely of @code{import}s of your
+printer modules, followed by a call to a register pretty-printers with
+the current objfile.
+
+Taken as a whole, this approach will scale nicely to multiple
+inferiors, each potentially using a different library version.
+Embedding a version number in the Python package name will ensure that
+@value{GDBN} is able to load both sets of printers simultaneously.
+Then, because the search for pretty-printers is done by objfile, and
+because your auto-loaded code took care to register your library's
+printers with a specific objfile, @value{GDBN} will find the correct
+printers for the specific version of the library used by each
+inferior.
+
+To continue the @code{std::string} example (@pxref{Pretty Printing}),
+this code might appear in @code{gdb.libstdcxx.v6}:
+
+@smallexample
+def register_printers (objfile):
+ objfile.pretty_printers.add (str_lookup_function)
+@end smallexample
+
+@noindent
+And then the corresponding contents of the auto-load file would be:
+
+@smallexample
+import gdb.libstdcxx.v6
+gdb.libstdcxx.v6.register_printers (gdb.current_objfile ())
+@end smallexample
+
+@node Commands In Python
+@subsubsection Commands In Python
+
+@cindex commands in python
+@cindex python commands
+You can implement new @value{GDBN} CLI commands in Python. A CLI
+command is implemented using an instance of the @code{gdb.Command}
+class, most commonly using a subclass.
+
+@defmethod Command __init__ name @var{command_class} @r{[}@var{completer_class}@r{]} @r{[}@var{prefix}@r{]}
+The object initializer for @code{Command} registers the new command
+with @value{GDBN}. This initializer is normally invoked from the
+subclass' own @code{__init__} method.
+
+@var{name} is the name of the command. If @var{name} consists of
+multiple words, then the initial words are looked for as prefix
+commands. In this case, if one of the prefix commands does not exist,
+an exception is raised.
+
+There is no support for multi-line commands.
+
+@var{command_class} should be one of the @samp{COMMAND_} constants
+defined below. This argument tells @value{GDBN} how to categorize the
+new command in the help system.
+
+@var{completer_class} is an optional argument. If given, it should be
+one of the @samp{COMPLETE_} constants defined below. This argument
+tells @value{GDBN} how to perform completion for this command. If not
+given, @value{GDBN} will attempt to complete using the object's
+@code{complete} method (see below); if no such method is found, an
+error will occur when completion is attempted.
+
+@var{prefix} is an optional argument. If @code{True}, then the new
+command is a prefix command; sub-commands of this command may be
+registered.
+
+The help text for the new command is taken from the Python
+documentation string for the command's class, if there is one. If no
+documentation string is provided, the default value ``This command is
+not documented.'' is used.
+@end defmethod
+
+@cindex don't repeat Python command
+@defmethod Command dont_repeat
+By default, a @value{GDBN} command is repeated when the user enters a
+blank line at the command prompt. A command can suppress this
+behavior by invoking the @code{dont_repeat} method. This is similar
+to the user command @code{dont-repeat}, see @ref{Define, dont-repeat}.
+@end defmethod
+
+@defmethod Command invoke argument from_tty
+This method is called by @value{GDBN} when this command is invoked.
+
+@var{argument} is a string. It is the argument to the command, after
+leading and trailing whitespace has been stripped.
+
+@var{from_tty} is a boolean argument. When true, this means that the
+command was entered by the user at the terminal; when false it means
+that the command came from elsewhere.
+
+If this method throws an exception, it is turned into a @value{GDBN}
+@code{error} call. Otherwise, the return value is ignored.
+@end defmethod
+
+@cindex completion of Python commands
+@defmethod Command complete text word
+This method is called by @value{GDBN} when the user attempts
+completion on this command. All forms of completion are handled by
+this method, that is, the @key{TAB} and @key{M-?} key bindings
+(@pxref{Completion}), and the @code{complete} command (@pxref{Help,
+complete}).
+
+The arguments @var{text} and @var{word} are both strings. @var{text}
+holds the complete command line up to the cursor's location.
+@var{word} holds the last word of the command line; this is computed
+using a word-breaking heuristic.
+
+The @code{complete} method can return several values:
+@itemize @bullet
+@item
+If the return value is a sequence, the contents of the sequence are
+used as the completions. It is up to @code{complete} to ensure that the
+contents actually do complete the word. A zero-length sequence is
+allowed, it means that there were no completions available. Only
+string elements of the sequence are used; other elements in the
+sequence are ignored.
+
+@item
+If the return value is one of the @samp{COMPLETE_} constants defined
+below, then the corresponding @value{GDBN}-internal completion
+function is invoked, and its result is used.
+
+@item
+All other results are treated as though there were no available
+completions.
+@end itemize
@end defmethod
When a new command is registered, it must be declared as a member of
Python code is read into @value{GDBN}, you may need to import the
@code{gdb} module explicitly.
+@node Functions In Python
+@subsubsection Writing new convenience functions
+
+@cindex writing convenience functions
+@cindex convenience functions in python
+@cindex python convenience functions
+@tindex gdb.Function
+@tindex Function
+You can implement new convenience functions (@pxref{Convenience Vars})
+in Python. A convenience function is an instance of a subclass of the
+class @code{gdb.Function}.
+
+@defmethod Function __init__ name
+The initializer for @code{Function} registers the new function with
+@value{GDBN}. The argument @var{name} is the name of the function,
+a string. The function will be visible to the user as a convenience
+variable of type @code{internal function}, whose name is the same as
+the given @var{name}.
+
+The documentation for the new function is taken from the documentation
+string for the new class.
+@end defmethod
+
+@defmethod Function invoke @var{*args}
+When a convenience function is evaluated, its arguments are converted
+to instances of @code{gdb.Value}, and then the function's
+@code{invoke} method is called. Note that @value{GDBN} does not
+predetermine the arity of convenience functions. Instead, all
+available arguments are passed to @code{invoke}, following the
+standard Python calling convention. In particular, a convenience
+function can have default values for parameters without ill effect.
+
+The return value of this method is used as its value in the enclosing
+expression. If an ordinary Python value is returned, it is converted
+to a @code{gdb.Value} following the usual rules.
+@end defmethod
+
+The following code snippet shows how a trivial convenience function can
+be implemented in Python:
+
+@smallexample
+class Greet (gdb.Function):
+ """Return string to greet someone.
+Takes a name as argument."""
+
+ def __init__ (self):
+ super (Greet, self).__init__ ("greet")
+
+ def invoke (self, name):
+ return "Hello, %s!" % name.string ()
+
+Greet ()
+@end smallexample
+
+The last line instantiates the class, and is necessary to trigger the
+registration of the function with @value{GDBN}. Depending on how the
+Python code is read into @value{GDBN}, you may need to import the
+@code{gdb} module explicitly.
+
+@node Objfiles In Python
+@subsubsection Objfiles In Python
+
+@cindex objfiles in python
+@tindex gdb.Objfile
+@tindex Objfile
+@value{GDBN} loads symbols for an inferior from various
+symbol-containing files (@pxref{Files}). These include the primary
+executable file, any shared libraries used by the inferior, and any
+separate debug info files (@pxref{Separate Debug Files}).
+@value{GDBN} calls these symbol-containing files @dfn{objfiles}.
+
+The following objfile-related functions are available in the
+@code{gdb} module:
+
+@findex gdb.current_objfile
+@defun current_objfile
+When auto-loading a Python script (@pxref{Auto-loading}), @value{GDBN}
+sets the ``current objfile'' to the corresponding objfile. This
+function returns the current objfile. If there is no current objfile,
+this function returns @code{None}.
+@end defun
+
+@findex gdb.objfiles
+@defun objfiles
+Return a sequence of all the objfiles current known to @value{GDBN}.
+@xref{Objfiles In Python}.
+@end defun
+
+Each objfile is represented by an instance of the @code{gdb.Objfile}
+class.
+
+@defivar Objfile filename
+The file name of the objfile as a string.
+@end defivar
+
+@defivar Objfile pretty_printers
+The @code{pretty_printers} attribute is a list of functions. It is
+used to look up pretty-printers. A @code{Value} is passed to each
+function in order; if the function returns @code{None}, then the
+search continues. Otherwise, the return value should be an object
+which is used to format the value. @xref{Pretty Printing}, for more
+information.
+@end defivar
+
+@node Frames In Python
+@subsubsection Acessing inferior stack frames from Python.
+
+@cindex frames in python
+When the debugged program stops, @value{GDBN} is able to analyze its call
+stack (@pxref{Frames,,Stack frames}). The @code{gdb.Frame} class
+represents a frame in the stack. A @code{gdb.Frame} object is only valid
+while its corresponding frame exists in the inferior's stack. If you try
+to use an invalid frame object, @value{GDBN} will throw a @code{RuntimeError}
+exception.
+
+Two @code{gdb.Frame} objects can be compared for equality with the @code{==}
+operator, like:
+
+@smallexample
+(@value{GDBP}) python print gdb.newest_frame() == gdb.selected_frame ()
+True
+@end smallexample
+
+The following frame-related functions are available in the @code{gdb} module:
+
+@findex gdb.selected_frame
+@defun selected_frame
+Return the selected frame object. (@pxref{Selection,,Selecting a Frame}).
+@end defun
+
+@defun frame_stop_reason_string reason
+Return a string explaining the reason why @value{GDBN} stopped unwinding
+frames, as expressed by the given @var{reason} code (an integer, see the
+@code{unwind_stop_reason} method further down in this section).
+@end defun
+
+A @code{gdb.Frame} object has the following methods:
+
+@table @code
+@defmethod Frame is_valid
+Returns true if the @code{gdb.Frame} object is valid, false if not.
+A frame object can become invalid if the frame it refers to doesn't
+exist anymore in the inferior. All @code{gdb.Frame} methods will throw
+an exception if it is invalid at the time the method is called.
+@end defmethod
+
+@defmethod Frame name
+Returns the function name of the frame, or @code{None} if it can't be
+obtained.
+@end defmethod
+
+@defmethod Frame type
+Returns the type of the frame. The value can be one of
+@code{gdb.NORMAL_FRAME}, @code{gdb.DUMMY_FRAME}, @code{gdb.SIGTRAMP_FRAME}
+or @code{gdb.SENTINEL_FRAME}.
+@end defmethod
+
+@defmethod Frame unwind_stop_reason
+Return an integer representing the reason why it's not possible to find
+more frames toward the outermost frame. Use
+@code{gdb.frame_stop_reason_string} to convert the value returned by this
+function to a string.
+@end defmethod
+
+@defmethod Frame pc
+Returns the frame's resume address.
+@end defmethod
+
+@defmethod Frame older
+Return the frame that called this frame.
+@end defmethod
+
+@defmethod Frame newer
+Return the frame called by this frame.
+@end defmethod
+
+@defmethod Frame read_var variable
+Return the value of the given variable in this frame. @var{variable} must
+be a string.
+@end defmethod
+@end table
+
+@node Lazy Strings In Python
+@subsubsection Python representation of lazy strings.
+
+@cindex lazy strings in python
+@tindex gdb.LazyString
+
+A @dfn{lazy string} is a string whose contents is not retrieved or
+encoded until it is needed.
+
+A @code{gdb.LazyString} is represented in @value{GDBN} as an
+@code{address} that points to a region of memory, an @code{encoding}
+that will be used to encode that region of memory, and a @code{length}
+to delimit the region of memory that represents the string. The
+difference between a @code{gdb.LazyString} and a string wrapped within
+a @code{gdb.Value} is that a @code{gdb.LazyString} will be treated
+differently by @value{GDBN} when printing. A @code{gdb.LazyString} is
+retrieved and encoded during printing, while a @code{gdb.Value}
+wrapping a string is immediately retrieved and encoded on creation.
+
+A @code{gdb.LazyString} object has the following functions:
+
+@defmethod LazyString value
+Convert the @code{gdb.LazyString} to a @code{gdb.Value}. This value
+will point to the string in memory, but will lose all the delayed
+retrieval, encoding and handling that @value{GDBN} applies to a
+@code{gdb.LazyString}.
+@end defmethod
+
+@defivar LazyString address
+This attribute holds the address of the string. This attribute is not
+writable.
+@end defivar
+
+@defivar LazyString length
+This attribute holds the length of the string in characters. If the
+length is -1, then the string will be fetched and encoded up to the
+first null of appropriate width. This attribute is not writable.
+@end defivar
+
+@defivar LazyString encoding
+This attribute holds the encoding that will be applied to the string
+when the string is printed by @value{GDBN}. If the encoding is not
+set, or contains an empty string, then @value{GDBN} will select the
+most appropriate encoding when the string is printed. This attribute
+is not writable.
+@end defivar
+
+@defivar LazyString type
+This attribute holds the type that is represented by the lazy string's
+type. For a lazy string this will always be a pointer type. To
+resolve this to the lazy string's character type, use the type's
+@code{target} method. @xref{Types In Python}. This attribute is not
+writable.
+@end defivar
+
@node Interpreters
@chapter Command Interpreters
@cindex command interpreters
we recommend that the frontend refreshes all the information shown in
the user interface.
+
+@menu
+* Context management::
+* Asynchronous and non-stop modes::
+* Thread groups::
+@end menu
+
+@node Context management
@subsection Context management
In most cases when @value{GDBN} accesses the target, this access is
right, so it is suggested to just always pass the @samp{--thread} and
@samp{--frame} options.
+@node Asynchronous and non-stop modes
@subsection Asynchronous command execution and non-stop mode
On some targets, @value{GDBN} is capable of processing MI commands
@code{-exec-interrupt}, to stop a thread, and @code{-thread-info},
to find the state of a thread, will always work.
+@node Thread groups
@subsection Thread groups
@value{GDBN} may be used to debug several processes at the same time.
On some platfroms, @value{GDBN} may support debugging of several
* GDB/MI Stream Records::
* GDB/MI Async Records::
* GDB/MI Frame Information::
+* GDB/MI Thread Information::
@end menu
@node GDB/MI Result Records
all threads together, or even for a single thread, if the thread must
be stepped though some code before letting it run freely.
-@item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}"
+@item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}",core="@var{core}"
The target has stopped. The @var{reason} field can have one of the
following values:
value of @code{"all"}. Otherwise, the value of the @var{stopped}
field will be a list of thread identifiers. Presently, this list will
always include a single thread, but frontend should be prepared to see
-several threads in the list.
+several threads in the list. The @var{core} field reports the
+processor core on which the stop event has happened. This field may be absent
+if such information is not available.
@item =thread-group-created,id="@var{id}"
@itemx =thread-group-exited,id="@var{id}"
@end table
+@node GDB/MI Thread Information
+@subsection @sc{gdb/mi} Thread Information
+
+Whenever @value{GDBN} has to report an information about a thread, it
+uses a tuple with the following fields:
+
+@table @code
+@item id
+The numeric id assigned to the thread by @value{GDBN}. This field is
+always present.
+
+@item target-id
+Target-specific string identifying the thread. This field is always present.
+
+@item details
+Additional information about the thread provided by the target.
+It is supposed to be human-readable and not interpreted by the
+frontend. This field is optional.
+
+@item state
+Either @samp{stopped} or @samp{running}, depending on whether the
+thread is presently running. This field is always present.
+
+@item core
+The value of this field is an integer number of the processor core the
+thread was last seen on. This field is optional.
+@end table
+
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@node GDB/MI Simple Examples
<- ^exit
@end smallexample
+Please note that @samp{^exit} is printed immediately, but it might
+take some time for @value{GDBN} to actually exit. During that time, @value{GDBN}
+performs necessary cleanups, including killing programs being debugged
+or disconnecting from debug hardware, so the frontend should wait till
+@value{GDBN} exits and should only forcibly kill @value{GDBN} if it
+fails to exit in reasonable time.
+
@subheading A Bad Command
Here's what happens if you pass a non-existent command:
@ignore
@subheading The @code{-break-catch} Command
@findex -break-catch
+@end ignore
@subheading The @code{-break-commands} Command
@findex -break-commands
-@end ignore
+@subsubheading Synopsis
+
+@smallexample
+ -break-commands @var{number} [ @var{command1} ... @var{commandN} ]
+@end smallexample
+
+Specifies the CLI commands that should be executed when breakpoint
+@var{number} is hit. The parameters @var{command1} to @var{commandN}
+are the commands. If no command is specified, any previously-set
+commands are cleared. @xref{Break Commands}. Typical use of this
+functionality is tracing a program, that is, printing of values of
+some variables whenever breakpoint is hit and then continuing.
+
+@subsubheading @value{GDBN} Command
+
+The corresponding @value{GDBN} command is @samp{commands}.
+
+@subsubheading Example
+
+@smallexample
+(gdb)
+-break-insert main
+^done,bkpt=@{number="1",type="breakpoint",disp="keep",
+enabled="y",addr="0x000100d0",func="main",file="hello.c",
+fullname="/home/foo/hello.c",line="5",times="0"@}
+(gdb)
+-break-commands 1 "print v" "continue"
+^done
+(gdb)
+@end smallexample
@subheading The @code{-break-condition} Command
@findex -break-condition
@end smallexample
+@ignore
@subheading The @code{-exec-show-arguments} Command
@findex -exec-show-arguments
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-environment-cd} Command
(gdb)
@end smallexample
+@subheading The @code{-exec-jump} Command
+@findex -exec-jump
+
+@subsubheading Synopsis
+
+@smallexample
+ -exec-jump @var{location}
+@end smallexample
+
+Resumes execution of the inferior program at the location specified by
+parameter. @xref{Specify Location}, for a description of the
+different forms of @var{location}.
+
+@subsubheading @value{GDBN} Command
+
+The corresponding @value{GDBN} command is @samp{jump}.
+
+@subsubheading Example
+
+@smallexample
+-exec-jump foo.c:10
+*running,thread-id="all"
+^running
+@end smallexample
+
@subheading The @code{-exec-next} Command
@findex -exec-next
@subsubheading Synopsis
@smallexample
- -stack-list-arguments @var{show-values}
+ -stack-list-arguments @var{print-values}
[ @var{low-frame} @var{high-frame} ]
@end smallexample
@var{high-frame} may be larger than the actual number of frames, in
which case only existing frames will be returned.
-The @var{show-values} argument must have a value of 0 or 1. A value of
-0 means that only the names of the arguments are listed, a value of 1
-means that both names and values of the arguments are printed.
+If @var{print-values} is 0 or @code{--no-values}, print only the names of
+the variables; if it is 1 or @code{--all-values}, print also their
+values; and if it is 2 or @code{--simple-values}, print the name,
+type and value for simple data types, and the name and type for arrays,
+structures and unions.
+
+Use of this command to obtain arguments in a single frame is
+deprecated in favor of the @samp{-stack-list-variables} command.
@subsubheading @value{GDBN} Command
@var{print-values} is 0 or @code{--no-values}, print only the names of
the variables; if it is 1 or @code{--all-values}, print also their
values; and if it is 2 or @code{--simple-values}, print the name,
-type and value for simple data types and the name and type for arrays,
+type and value for simple data types, and the name and type for arrays,
structures and unions. In this last case, a frontend can immediately
display the value of simple data types and create variable objects for
other data types when the user wishes to explore their values in
more detail.
+This command is deprecated in favor of the
+@samp{-stack-list-variables} command.
+
@subsubheading @value{GDBN} Command
@samp{info locals} in @value{GDBN}, @samp{gdb_get_locals} in @code{gdbtk}.
(gdb)
@end smallexample
+@subheading The @code{-stack-list-variables} Command
+@findex -stack-list-variables
+
+@subsubheading Synopsis
+
+@smallexample
+ -stack-list-variables @var{print-values}
+@end smallexample
+
+Display the names of local variables and function arguments for the selected frame. If
+@var{print-values} is 0 or @code{--no-values}, print only the names of
+the variables; if it is 1 or @code{--all-values}, print also their
+values; and if it is 2 or @code{--simple-values}, print the name,
+type and value for simple data types, and the name and type for arrays,
+structures and unions.
+
+@subsubheading Example
+
+@smallexample
+(gdb)
+-stack-list-variables --thread 1 --frame 0 --all-values
+^done,variables=[@{name="x",value="11"@},@{name="s",value="@{a = 1, b = 2@}"@}]
+(gdb)
+@end smallexample
+
@subheading The @code{-stack-select-frame} Command
@findex -stack-select-frame
@item @strong{Operation}
@tab @strong{Description}
+@item @code{-enable-pretty-printing}
+@tab enable Python-based pretty-printing
@item @code{-var-create}
@tab create a variable object
@item @code{-var-delete}
@tab update the variable and its children
@item @code{-var-set-frozen}
@tab set frozeness attribute
+@item @code{-var-set-update-range}
+@tab set range of children to display on update
@end multitable
In the next subsection we describe each operation in detail and suggest
@subheading Description And Use of Operations on Variable Objects
+@subheading The @code{-enable-pretty-printing} Command
+@findex -enable-pretty-printing
+
+@smallexample
+-enable-pretty-printing
+@end smallexample
+
+@value{GDBN} allows Python-based visualizers to affect the output of the
+MI variable object commands. However, because there was no way to
+implement this in a fully backward-compatible way, a front end must
+request that this functionality be enabled.
+
+Once enabled, this feature cannot be disabled.
+
+Note that if Python support has not been compiled into @value{GDBN},
+this command will still succeed (and do nothing).
+
+This feature is currently (as of @value{GDBN} 7.0) experimental, and
+may work differently in future versions of @value{GDBN}.
+
@subheading The @code{-var-create} Command
@findex -var-create
@samp{$@var{regname}} --- a CPU register name
@end itemize
+@cindex dynamic varobj
+A varobj's contents may be provided by a Python-based pretty-printer. In this
+case the varobj is known as a @dfn{dynamic varobj}. Dynamic varobjs
+have slightly different semantics in some cases. If the
+@code{-enable-pretty-printing} command is not sent, then @value{GDBN}
+will never create a dynamic varobj. This ensures backward
+compatibility for existing clients.
+
@subsubheading Result
-This operation returns the name, number of children and the type of the
-object created. Type is returned as a string as the ones generated by
-the @value{GDBN} CLI. If a fixed variable object is bound to a
-specific thread, the thread is is also printed:
+This operation returns attributes of the newly-created varobj. These
+are:
+
+@table @samp
+@item name
+The name of the varobj.
+
+@item numchild
+The number of children of the varobj. This number is not necessarily
+reliable for a dynamic varobj. Instead, you must examine the
+@samp{has_more} attribute.
+
+@item value
+The varobj's scalar value. For a varobj whose type is some sort of
+aggregate (e.g., a @code{struct}), or for a dynamic varobj, this value
+will not be interesting.
+
+@item type
+The varobj's type. This is a string representation of the type, as
+would be printed by the @value{GDBN} CLI.
+
+@item thread-id
+If a variable object is bound to a specific thread, then this is the
+thread's identifier.
+
+@item has_more
+For a dynamic varobj, this indicates whether there appear to be any
+children available. For a non-dynamic varobj, this will be 0.
+
+@item dynamic
+This attribute will be present and have the value @samp{1} if the
+varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
+then this attribute will not be present.
+
+@item displayhint
+A dynamic varobj can supply a display hint to the front end. The
+value comes directly from the Python pretty-printer object's
+@code{display_hint} method. @xref{Pretty Printing}.
+@end table
+
+Typical output will look like this:
@smallexample
- name="@var{name}",numchild="@var{N}",type="@var{type}",thread-id="@var{M}"
+ name="@var{name}",numchild="@var{N}",type="@var{type}",thread-id="@var{M}",
+ has_more="@var{has_more}"
@end smallexample
numchild=@var{n}
@end smallexample
+Note that this number is not completely reliable for a dynamic varobj.
+It will return the current number of children, but more children may
+be available.
+
@subheading The @code{-var-list-children} Command
@findex -var-list-children
@subsubheading Synopsis
@smallexample
- -var-list-children [@var{print-values}] @var{name}
+ -var-list-children [@var{print-values}] @var{name} [@var{from} @var{to}]
@end smallexample
-@anchor{-var-list-children}
+@anchor{-var-list-children}
Return a list of the children of the specified variable object and
create variable objects for them, if they do not already exist. With
value for simple data types and just the name for arrays, structures
and unions.
+@var{from} and @var{to}, if specified, indicate the range of children
+to report. If @var{from} or @var{to} is less than zero, the range is
+reset and all children will be reported. Otherwise, children starting
+at @var{from} (zero-based) and up to and excluding @var{to} will be
+reported.
+
+If a child range is requested, it will only affect the current call to
+@code{-var-list-children}, but not future calls to @code{-var-update}.
+For this, you must instead use @code{-var-set-update-range}. The
+intent of this approach is to enable a front end to implement any
+update approach it likes; for example, scrolling a view may cause the
+front end to request more children with @code{-var-list-children}, and
+then the front end could call @code{-var-set-update-range} with a
+different range to ensure that future updates are restricted to just
+the visible items.
+
+For each child the following results are returned:
+
+@table @var
+
+@item name
+Name of the variable object created for this child.
+
+@item exp
+The expression to be shown to the user by the front end to designate this child.
+For example this may be the name of a structure member.
+
+For a dynamic varobj, this value cannot be used to form an
+expression. There is no way to do this at all with a dynamic varobj.
+
+For C/C@t{++} structures there are several pseudo children returned to
+designate access qualifiers. For these pseudo children @var{exp} is
+@samp{public}, @samp{private}, or @samp{protected}. In this case the
+type and value are not present.
+
+A dynamic varobj will not report the access qualifying
+pseudo-children, regardless of the language. This information is not
+available at all with a dynamic varobj.
+
+@item numchild
+Number of children this child has. For a dynamic varobj, this will be
+0.
+
+@item type
+The type of the child.
+
+@item value
+If values were requested, this is the value.
+
+@item thread-id
+If this variable object is associated with a thread, this is the thread id.
+Otherwise this result is not present.
+
+@item frozen
+If the variable object is frozen, this variable will be present with a value of 1.
+@end table
+
+The result may have its own attributes:
+
+@table @samp
+@item displayhint
+A dynamic varobj can supply a display hint to the front end. The
+value comes directly from the Python pretty-printer object's
+@code{display_hint} method. @xref{Pretty Printing}.
+
+@item has_more
+This is an integer attribute which is nonzero if there are children
+remaining after the end of the selected range.
+@end table
+
@subsubheading Example
@smallexample
(gdb)
-var-list-children n
- ^done,numchild=@var{n},children=[@{name=@var{name},
+ ^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
numchild=@var{n},type=@var{type}@},@r{(repeats N times)}]
(gdb)
-var-list-children --all-values n
- ^done,numchild=@var{n},children=[@{name=@var{name},
+ ^done,numchild=@var{n},children=[child=@{name=@var{name},exp=@var{exp},
numchild=@var{n},value=@var{value},type=@var{type}@},@r{(repeats N times)}]
@end smallexample
the @code{-var-info-path-expression} command is creating a
watchpoint from a variable object.
+This command is currently not valid for children of a dynamic varobj,
+and will give an error when invoked on one.
+
For example, suppose @code{C} is a C@t{++} class, derived from class
@code{Base}, and that the @code{Base} class has a member called
@code{m_size}. Assume a variable @code{c} is has the type of
currently running thread, it will not be updated, without any
diagnostic.
+If @code{-var-set-update-range} was previously used on a varobj, then
+only the selected range of children will be reported.
+
+@code{-var-update} reports all the changed varobjs in a tuple named
+@samp{changelist}.
+
+Each item in the change list is itself a tuple holding:
+
+@table @samp
+@item name
+The name of the varobj.
+
+@item value
+If values were requested for this update, then this field will be
+present and will hold the value of the varobj.
+
+@item in_scope
+@anchor{-var-update}
+This field is a string which may take one of three values:
+
+@table @code
+@item "true"
+The variable object's current value is valid.
+
+@item "false"
+The variable object does not currently hold a valid value but it may
+hold one in the future if its associated expression comes back into
+scope.
+
+@item "invalid"
+The variable object no longer holds a valid value.
+This can occur when the executable file being debugged has changed,
+either through recompilation or by using the @value{GDBN} @code{file}
+command. The front end should normally choose to delete these variable
+objects.
+@end table
+
+In the future new values may be added to this list so the front should
+be prepared for this possibility. @xref{GDB/MI Development and Front Ends, ,@sc{GDB/MI} Development and Front Ends}.
+
+@item type_changed
+This is only present if the varobj is still valid. If the type
+changed, then this will be the string @samp{true}; otherwise it will
+be @samp{false}.
+
+@item new_type
+If the varobj's type changed, then this field will be present and will
+hold the new type.
+
+@item new_num_children
+For a dynamic varobj, if the number of children changed, or if the
+type changed, this will be the new number of children.
+
+The @samp{numchild} field in other varobj responses is generally not
+valid for a dynamic varobj -- it will show the number of children that
+@value{GDBN} knows about, but because dynamic varobjs lazily
+instantiate their children, this will not reflect the number of
+children which may be available.
+
+The @samp{new_num_children} attribute only reports changes to the
+number of children known by @value{GDBN}. This is the only way to
+detect whether an update has removed children (which necessarily can
+only happen at the end of the update range).
+
+@item displayhint
+The display hint, if any.
+
+@item has_more
+This is an integer value, which will be 1 if there are more children
+available outside the varobj's update range.
+
+@item dynamic
+This attribute will be present and have the value @samp{1} if the
+varobj is a dynamic varobj. If the varobj is not a dynamic varobj,
+then this attribute will not be present.
+
+@item new_children
+If new children were added to a dynamic varobj within the selected
+update range (as set by @code{-var-set-update-range}), then they will
+be listed in this attribute.
+@end table
+
@subsubheading Example
@smallexample
(gdb)
@end smallexample
-@anchor{-var-update}
-The field in_scope may take three values:
-
-@table @code
-@item "true"
-The variable object's current value is valid.
-
-@item "false"
-The variable object does not currently hold a valid value but it may
-hold one in the future if its associated expression comes back into
-scope.
-
-@item "invalid"
-The variable object no longer holds a valid value.
-This can occur when the executable file being debugged has changed,
-either through recompilation or by using the @value{GDBN} @code{file}
-command. The front end should normally choose to delete these variable
-objects.
-@end table
-
-In the future new values may be added to this list so the front should
-be prepared for this possibility. @xref{GDB/MI Development and Front Ends, ,@sc{GDB/MI} Development and Front Ends}.
-
@subheading The @code{-var-set-frozen} Command
@findex -var-set-frozen
@anchor{-var-set-frozen}
(gdb)
@end smallexample
+@subheading The @code{-var-set-update-range} command
+@findex -var-set-update-range
+@anchor{-var-set-update-range}
+
+@subsubheading Synopsis
+
+@smallexample
+ -var-set-update-range @var{name} @var{from} @var{to}
+@end smallexample
+
+Set the range of children to be returned by future invocations of
+@code{-var-update}.
+
+@var{from} and @var{to} indicate the range of children to report. If
+@var{from} or @var{to} is less than zero, the range is reset and all
+children will be reported. Otherwise, children starting at @var{from}
+(zero-based) and up to and excluding @var{to} will be reported.
+
+@subsubheading Example
+
+@smallexample
+(gdb)
+-var-set-update-range V 1 2
+^done
+@end smallexample
+
+@subheading The @code{-var-set-visualizer} command
+@findex -var-set-visualizer
+@anchor{-var-set-visualizer}
+
+@subsubheading Synopsis
+
+@smallexample
+ -var-set-visualizer @var{name} @var{visualizer}
+@end smallexample
+
+Set a visualizer for the variable object @var{name}.
+
+@var{visualizer} is the visualizer to use. The special value
+@samp{None} means to disable any visualizer in use.
+
+If not @samp{None}, @var{visualizer} must be a Python expression.
+This expression must evaluate to a callable object which accepts a
+single argument. @value{GDBN} will call this object with the value of
+the varobj @var{name} as an argument (this is done so that the same
+Python pretty-printing code can be used for both the CLI and MI).
+When called, this object must return an object which conforms to the
+pretty-printing interface (@pxref{Pretty Printing}).
+
+The pre-defined function @code{gdb.default_visualizer} may be used to
+select a visualizer by following the built-in process
+(@pxref{Selecting Pretty-Printers}). This is done automatically when
+a varobj is created, and so ordinarily is not needed.
+
+This feature is only available if Python support is enabled. The MI
+command @code{-list-features} (@pxref{GDB/MI Miscellaneous Commands})
+can be used to check this.
+
+@subsubheading Example
+
+Resetting the visualizer:
+
+@smallexample
+(gdb)
+-var-set-visualizer V None
+^done
+@end smallexample
+
+Reselecting the default (type-based) visualizer:
+
+@smallexample
+(gdb)
+-var-set-visualizer V gdb.default_visualizer
+^done
+@end smallexample
+
+Suppose @code{SomeClass} is a visualizer class. A lambda expression
+can be used to instantiate this class for a varobj:
+
+@smallexample
+(gdb)
+-var-set-visualizer V "lambda val: SomeClass()"
+^done
+@end smallexample
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@node GDB/MI Data Manipulation
@section @sc{gdb/mi} Symbol Query Commands
+@ignore
@subheading The @code{-symbol-info-address} Command
@findex -symbol-info-address
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-symbol-list-lines} Command
@end smallexample
+@ignore
@subheading The @code{-symbol-list-types} Command
@findex -symbol-list-types
@subsubheading Example
N.A.
+@end ignore
@c %%%%%%%%%%%%%%%%%%%%%%%%%%%% SECTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@end smallexample
+@ignore
@subheading The @code{-file-list-exec-sections} Command
@findex -file-list-exec-sections
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-file-list-exec-source-file} Command
(gdb)
@end smallexample
+@ignore
@subheading The @code{-file-list-shared-libraries} Command
@findex -file-list-shared-libraries
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-file-symbol-file} Command
(gdb)
@end smallexample
+@ignore
@subheading The @code{-target-compare-sections} Command
@findex -target-compare-sections
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-target-detach} Command
@end smallexample
+@ignore
@subheading The @code{-target-exec-status} Command
@findex -target-exec-status
@end smallexample
@c ????
+@end ignore
@subsubheading @value{GDBN} Command
@end smallexample
+@ignore
@subheading The @code{-exec-abort} Command
@findex -exec-abort
@subsubheading Example
N.A.
+@end ignore
@subheading The @code{-gdb-set} Command
of @code{-varobj-create}.
@item pending-breakpoints
Indicates presence of the @option{-f} option to the @code{-break-insert} command.
+@item python
+Indicates presence of Python scripting support, Python-based
+pretty-printing commands, and possible presence of the
+@samp{display_hint} field in the output of @code{-var-list-children}
@item thread-info
Indicates presence of the @code{-thread-info} command.
@subheading Synopsis
@smallexample
--list-thread-groups [ --available ] [ @var{group} ]
+-list-thread-groups [ --available ] [ --recurse 1 ] [ @var{group} ... ]
@end smallexample
-When used without the @var{group} parameter, lists top-level thread
-groups that are being debugged. When used with the @var{group}
-parameter, the children of the specified group are listed. The
-children can be either threads, or other groups. At present,
-@value{GDBN} will not report both threads and groups as children at
-the same time, but it may change in future.
+Lists thread groups (@pxref{Thread groups}). When a single thread
+group is passed as the argument, lists the children of that group.
+When several thread group are passed, lists information about those
+thread groups. Without any parameters, lists information about all
+top-level thread groups.
+
+Normally, thread groups that are being debugged are reported.
+With the @samp{--available} option, @value{GDBN} reports thread groups
+available on the target.
+
+The output of this command may have either a @samp{threads} result or
+a @samp{groups} result. The @samp{thread} result has a list of tuples
+as value, with each tuple describing a thread (@pxref{GDB/MI Thread
+Information}). The @samp{groups} result has a list of tuples as value,
+each tuple describing a thread group. If top-level groups are
+requested (that is, no parameter is passed), or when several groups
+are passed, the output always has a @samp{groups} result. The format
+of the @samp{group} result is described below.
+
+To reduce the number of roundtrips it's possible to list thread groups
+together with their children, by passing the @samp{--recurse} option
+and the recursion depth. Presently, only recursion depth of 1 is
+permitted. If this option is present, then every reported thread group
+will also include its children, either as @samp{group} or
+@samp{threads} field.
+
+In general, any combination of option and parameters is permitted, with
+the following caveats:
+
+@itemize @bullet
+@item
+When a single thread group is passed, the output will typically
+be the @samp{threads} result. Because threads may not contain
+anything, the @samp{recurse} option will be ignored.
+
+@item
+When the @samp{--available} option is passed, limited information may
+be available. In particular, the list of threads of a process might
+be inaccessible. Further, specifying specific thread groups might
+not give any performance advantage over listing all thread groups.
+The frontend should assume that @samp{-list-thread-groups --available}
+is always an expensive operation and cache the results.
+
+@end itemize
+
+The @samp{groups} result is a list of tuples, where each tuple may
+have the following fields:
+
+@table @code
+@item id
+Identifier of the thread group. This field is always present.
+
+@item type
+The type of the thread group. At present, only @samp{process} is a
+valid type.
+
+@item pid
+The target-specific process identifier. This field is only present
+for thread groups of type @samp{process}.
+
+@item num_children
+The number of children this thread group has. This field may be
+absent for an available thread group.
+
+@item threads
+This field has a list of tuples as value, each tuple describing a
+thread. It may be present if the @samp{--recurse} option is
+specified, and it's actually possible to obtain the threads.
-With the @samp{--available} option, instead of reporting groups that
-are been debugged, GDB will report all thread groups available on the
-target. Using the @samp{--available} option together with @var{group}
-is not allowed.
+@item cores
+This field is a list of integers, each identifying a core that one
+thread of the group is running on. This field may be absent if
+such information is not available.
+
+@end table
@subheading Example
@{id="1",target-id="Thread 0xb7e156b0 (LWP 21254)",
frame=@{level="0",addr="0x0804891f",func="foo",args=[@{name="i",value="10"@}],
file="/tmp/a.c",fullname="/tmp/a.c",line="158"@},state="running"@}]]
+-list-thread-groups --available
+^done,groups=[@{id="17",type="process",pid="yyy",num_children="2",cores=[1,2]@}]
+-list-thread-groups --available --recurse 1
+ ^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
+ threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
+ @{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},..]
+-list-thread-groups --available --recurse 1 17 18
+^done,groups=[@{id="17", types="process",pid="yyy",num_children="2",cores=[1,2],
+ threads=[@{id="1",target-id="Thread 0xb7e14b90",cores=[1]@},
+ @{id="2",target-id="Thread 0xb7e14b90",cores=[2]@}]@},...]
@end smallexample
@subheading The @code{-interpreter-exec} Command
means that commands can be run behind a user's back by a front-end in
a transparent manner.
-The server prefix does not affect the recording of values into the value
-history; to print a value without recording it into the value history,
-use the @code{output} command instead of the @code{print} command.
+The @code{server } prefix does not affect the recording of values into
+the value history; to print a value without recording it into the
+value history, use the @code{output} command instead of the
+@code{print} command.
+
+Using this prefix also disables confirmation requests
+(@pxref{confirmation requests}).
@node Prompting
@section Annotation for @value{GDBN} Input
followed by one or more lowercase hex digits (note that this does not
depend on the language).
+@node JIT Interface
+@chapter JIT Compilation Interface
+@cindex just-in-time compilation
+@cindex JIT compilation interface
+
+This chapter documents @value{GDBN}'s @dfn{just-in-time} (JIT) compilation
+interface. A JIT compiler is a program or library that generates native
+executable code at runtime and executes it, usually in order to achieve good
+performance while maintaining platform independence.
+
+Programs that use JIT compilation are normally difficult to debug because
+portions of their code are generated at runtime, instead of being loaded from
+object files, which is where @value{GDBN} normally finds the program's symbols
+and debug information. In order to debug programs that use JIT compilation,
+@value{GDBN} has an interface that allows the program to register in-memory
+symbol files with @value{GDBN} at runtime.
+
+If you are using @value{GDBN} to debug a program that uses this interface, then
+it should work transparently so long as you have not stripped the binary. If
+you are developing a JIT compiler, then the interface is documented in the rest
+of this chapter. At this time, the only known client of this interface is the
+LLVM JIT.
+
+Broadly speaking, the JIT interface mirrors the dynamic loader interface. The
+JIT compiler communicates with @value{GDBN} by writing data into a global
+variable and calling a fuction at a well-known symbol. When @value{GDBN}
+attaches, it reads a linked list of symbol files from the global variable to
+find existing code, and puts a breakpoint in the function so that it can find
+out about additional code.
+
+@menu
+* Declarations:: Relevant C struct declarations
+* Registering Code:: Steps to register code
+* Unregistering Code:: Steps to unregister code
+@end menu
+
+@node Declarations
+@section JIT Declarations
+
+These are the relevant struct declarations that a C program should include to
+implement the interface:
+
+@smallexample
+typedef enum
+@{
+ JIT_NOACTION = 0,
+ JIT_REGISTER_FN,
+ JIT_UNREGISTER_FN
+@} jit_actions_t;
+
+struct jit_code_entry
+@{
+ struct jit_code_entry *next_entry;
+ struct jit_code_entry *prev_entry;
+ const char *symfile_addr;
+ uint64_t symfile_size;
+@};
+
+struct jit_descriptor
+@{
+ uint32_t version;
+ /* This type should be jit_actions_t, but we use uint32_t
+ to be explicit about the bitwidth. */
+ uint32_t action_flag;
+ struct jit_code_entry *relevant_entry;
+ struct jit_code_entry *first_entry;
+@};
+
+/* GDB puts a breakpoint in this function. */
+void __attribute__((noinline)) __jit_debug_register_code() @{ @};
+
+/* Make sure to specify the version statically, because the
+ debugger may check the version before we can set it. */
+struct jit_descriptor __jit_debug_descriptor = @{ 1, 0, 0, 0 @};
+@end smallexample
+
+If the JIT is multi-threaded, then it is important that the JIT synchronize any
+modifications to this global data properly, which can easily be done by putting
+a global mutex around modifications to these structures.
+
+@node Registering Code
+@section Registering Code
+
+To register code with @value{GDBN}, the JIT should follow this protocol:
+
+@itemize @bullet
+@item
+Generate an object file in memory with symbols and other desired debug
+information. The file must include the virtual addresses of the sections.
+
+@item
+Create a code entry for the file, which gives the start and size of the symbol
+file.
+
+@item
+Add it to the linked list in the JIT descriptor.
+
+@item
+Point the relevant_entry field of the descriptor at the entry.
+
+@item
+Set @code{action_flag} to @code{JIT_REGISTER} and call
+@code{__jit_debug_register_code}.
+@end itemize
+
+When @value{GDBN} is attached and the breakpoint fires, @value{GDBN} uses the
+@code{relevant_entry} pointer so it doesn't have to walk the list looking for
+new code. However, the linked list must still be maintained in order to allow
+@value{GDBN} to attach to a running process and still find the symbol files.
+
+@node Unregistering Code
+@section Unregistering Code
+
+If code is freed, then the JIT should use the following protocol:
+
+@itemize @bullet
+@item
+Remove the code entry corresponding to the code from the linked list.
+
+@item
+Point the @code{relevant_entry} field of the descriptor at the code entry.
+
+@item
+Set @code{action_flag} to @code{JIT_UNREGISTER} and call
+@code{__jit_debug_register_code}.
+@end itemize
+
+If the JIT frees or recompiles code without unregistering it, then @value{GDBN}
+and the JIT will leak the memory used for the associated symbol files.
+
@node GDB Bugs
@chapter Reporting Bugs in @value{GDBN}
@cindex bugs in @value{GDBN}
distribution; if it is not, you can get the latest version from
@url{http://zlib.net}.
+@item iconv
+@value{GDBN}'s features related to character sets (@pxref{Character
+Sets}) require a functioning @code{iconv} implementation. If you are
+on a GNU system, then this is provided by the GNU C Library. Some
+other systems also provide a working @code{iconv}.
+
+On systems with @code{iconv}, you can install GNU Libiconv. If you
+have previously installed Libiconv, you can use the
+@option{--with-libiconv-prefix} option to configure.
+
+@value{GDBN}'s top-level @file{configure} and @file{Makefile} will
+arrange to build Libiconv if a directory named @file{libiconv} appears
+in the top-most source directory. If Libiconv is built this way, and
+if the operating system does not provide a suitable @code{iconv}
+implementation, then the just-built library will automatically be used
+by @value{GDBN}. One easy way to set this up is to download GNU
+Libiconv, unpack it, and then rename the directory holding the
+Libiconv source code to @samp{libiconv}.
@end table
@node Running Configure
@table @code
@kindex maint agent
+@kindex maint agent-eval
@item maint agent @var{expression}
+@itemx maint agent-eval @var{expression}
Translate the given @var{expression} into remote agent bytecodes.
This command is useful for debugging the Agent Expression mechanism
-(@pxref{Agent Expressions}).
+(@pxref{Agent Expressions}). The @samp{agent} version produces an
+expression useful for data collection, such as by tracepoints, while
+@samp{maint agent-eval} produces an expression that evaluates directly
+to a result. For instance, a collection expression for @code{globa +
+globb} will include bytecodes to record four bytes of memory at each
+of the addresses of @code{globa} and @code{globb}, while discarding
+the result of the addition, while an evaluation expression will do the
+addition and return the sum.
@kindex maint info breakpoints
@item @anchor{maint info breakpoints}maint info breakpoints
Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be
compiled with the @samp{-pg} compiler option.
-@kindex maint show-debug-regs
-@cindex x86 hardware debug registers
-@item maint show-debug-regs
-Control whether to show variables that mirror the x86 hardware debug
+@kindex maint set show-debug-regs
+@kindex maint show show-debug-regs
+@cindex hardware debug registers
+@item maint set show-debug-regs
+@itemx maint show show-debug-regs
+Control whether to show variables that mirror the hardware debug
registers. Use @code{ON} to enable, @code{OFF} to disable. If
enabled, the debug registers values are shown when @value{GDBN} inserts or
removes a hardware breakpoint or watchpoint, and when the inferior
* Packets::
* Stop Reply Packets::
* General Query Packets::
-* Register Packet Format::
+* Architecture-Specific Protocol Details::
* Tracepoint Packets::
* Host I/O Packets::
* Interrupts::
* File-I/O Remote Protocol Extension::
* Library List Format::
* Memory Map Format::
+* Thread List Format::
@end menu
@node Overview
Don't use this packet. Use the @samp{Z} and @samp{z} packets instead
(@pxref{insert breakpoint or watchpoint packet}).
-@item bc
@cindex @samp{bc} packet
+@anchor{bc}
+@item bc
Backward continue. Execute the target system in reverse. No parameter.
@xref{Reverse Execution}, for more information.
Reply:
@xref{Stop Reply Packets}, for the reply specifications.
-@item bs
@cindex @samp{bs} packet
+@anchor{bs}
+@item bs
Backward single step. Execute one instruction in reverse. No parameter.
@xref{Reverse Execution}, for more information.
Step with signal @var{sig}. The signal @var{sig} should be two hex digits.
@item t
Stop.
-@item T @var{sig}
-Stop with signal @var{sig}. The signal @var{sig} should be two hex digits.
@end table
The optional argument @var{addr} normally associated with the
@samp{c}, @samp{C}, @samp{s}, and @samp{S} packets is
not supported in @samp{vCont}.
-The @samp{t} and @samp{T} actions are only relevant in non-stop mode
-(@pxref{Remote Non-Stop}) and may be ignored by the stub otherwise.
+The @samp{t} action is only relevant in non-stop mode
+(@pxref{Remote Non-Stop}) and may be ignored by the stub otherwise.
A stop reply should be generated for any affected thread not already stopped.
When a thread is stopped by means of a @samp{t} action,
the corresponding stop reply should indicate that the thread has stopped with
for an error
@end table
-@item z @var{type},@var{addr},@var{length}
-@itemx Z @var{type},@var{addr},@var{length}
+@item z @var{type},@var{addr},@var{kind}
+@itemx Z @var{type},@var{addr},@var{kind}
@anchor{insert breakpoint or watchpoint packet}
@cindex @samp{z} packet
@cindex @samp{Z} packets
Insert (@samp{Z}) or remove (@samp{z}) a @var{type} breakpoint or
-watchpoint starting at address @var{address} and covering the next
-@var{length} bytes.
+watchpoint starting at address @var{address} of kind @var{kind}.
Each breakpoint and watchpoint packet @var{type} is documented
separately.
avoid potential problems with duplicate packets, the operations should
be implemented in an idempotent way.}
-@item z0,@var{addr},@var{length}
-@itemx Z0,@var{addr},@var{length}
+@item z0,@var{addr},@var{kind}
+@itemx Z0,@var{addr},@var{kind}
@cindex @samp{z0} packet
@cindex @samp{Z0} packet
Insert (@samp{Z0}) or remove (@samp{z0}) a memory breakpoint at address
-@var{addr} of size @var{length}.
+@var{addr} of type @var{kind}.
A memory breakpoint is implemented by replacing the instruction at
@var{addr} with a software breakpoint or trap instruction. The
-@var{length} is used by targets that indicates the size of the
-breakpoint (in bytes) that should be inserted (e.g., the @sc{arm} and
-@sc{mips} can insert either a 2 or 4 byte breakpoint).
+@var{kind} is target-specific and typically indicates the size of
+the breakpoint in bytes that should be inserted. E.g., the @sc{arm}
+and @sc{mips} can insert either a 2 or 4 byte breakpoint. Some
+architectures have additional meanings for @var{kind};
+see @ref{Architecture-Specific Protocol Details}.
@emph{Implementation note: It is possible for a target to copy or move
code that contains memory breakpoints (e.g., when implementing
for an error
@end table
-@item z1,@var{addr},@var{length}
-@itemx Z1,@var{addr},@var{length}
+@item z1,@var{addr},@var{kind}
+@itemx Z1,@var{addr},@var{kind}
@cindex @samp{z1} packet
@cindex @samp{Z1} packet
Insert (@samp{Z1}) or remove (@samp{z1}) a hardware breakpoint at
-address @var{addr} of size @var{length}.
+address @var{addr}.
A hardware breakpoint is implemented using a mechanism that is not
-dependant on being able to modify the target's memory.
+dependant on being able to modify the target's memory. @var{kind}
+has the same meaning as in @samp{Z0} packets.
@emph{Implementation note: A hardware breakpoint is not affected by code
movement.}
for an error
@end table
-@item z2,@var{addr},@var{length}
-@itemx Z2,@var{addr},@var{length}
+@item z2,@var{addr},@var{kind}
+@itemx Z2,@var{addr},@var{kind}
@cindex @samp{z2} packet
@cindex @samp{Z2} packet
-Insert (@samp{Z2}) or remove (@samp{z2}) a write watchpoint.
+Insert (@samp{Z2}) or remove (@samp{z2}) a write watchpoint at @var{addr}.
+@var{kind} is interpreted as the number of bytes to watch.
Reply:
@table @samp
for an error
@end table
-@item z3,@var{addr},@var{length}
-@itemx Z3,@var{addr},@var{length}
+@item z3,@var{addr},@var{kind}
+@itemx Z3,@var{addr},@var{kind}
@cindex @samp{z3} packet
@cindex @samp{Z3} packet
-Insert (@samp{Z3}) or remove (@samp{z3}) a read watchpoint.
+Insert (@samp{Z3}) or remove (@samp{z3}) a read watchpoint at @var{addr}.
+@var{kind} is interpreted as the number of bytes to watch.
Reply:
@table @samp
for an error
@end table
-@item z4,@var{addr},@var{length}
-@itemx Z4,@var{addr},@var{length}
+@item z4,@var{addr},@var{kind}
+@itemx Z4,@var{addr},@var{kind}
@cindex @samp{z4} packet
@cindex @samp{Z4} packet
-Insert (@samp{Z4}) or remove (@samp{z4}) an access watchpoint.
+Insert (@samp{Z4}) or remove (@samp{z4}) an access watchpoint at @var{addr}.
+@var{kind} is interpreted as the number of bytes to watch.
Reply:
@table @samp
If @var{n} is @samp{thread}, then @var{r} is the @var{thread-id} of
the stopped thread, as specified in @ref{thread-id syntax}.
+@item
+If @var{n} is @samp{core}, then @var{r} is the hexadecimal number of
+the core on which the stop event was detected.
+
@item
If @var{n} is a recognized @dfn{stop reason}, it describes a more
specific event that stopped the target. The currently defined stop
beginning when executing backward) of the log. The value of @var{r}
will be either @samp{begin} or @samp{end}. @xref{Reverse Execution},
for more information.
-
-
@end table
@item W @var{AA}
@item qCRC:@var{addr},@var{length}
@cindex CRC of memory block, remote request
@cindex @samp{qCRC} packet
-Compute the CRC checksum of a block of memory.
+Compute the CRC checksum of a block of memory using CRC-32 defined in
+IEEE 802.3. The CRC is computed byte at a time, taking the most
+significant bit of each byte first. The initial pattern code
+@code{0xffffffff} is used to ensure leading zeros affect the CRC.
+
+@emph{Note:} This is the same CRC used in validating separate debug
+files (@pxref{Separate Debug Files, , Debugging Information in Separate
+Files}). However the algorithm is slightly different. When validating
+separate debug files, the CRC is computed taking the @emph{least}
+significant bit of each byte first, and the final result is inverted to
+detect trailing zeros.
+
Reply:
@table @samp
@item E @var{NN}
@tab @samp{-}
@tab Yes
+@item @samp{qXfer:threads:read}
+@tab No
+@tab @samp{-}
+@tab Yes
+
+
@item @samp{QNonStop}
@tab No
@tab @samp{-}
@tab @samp{-}
@tab No
+@item @samp{ConditionalTracepoints}
+@tab No
+@tab @samp{-}
+@tab No
+
+@item @samp{ReverseContinue}
+@tab No
+@tab @samp{-}
+@tab No
+
+@item @samp{ReverseStep}
+@tab No
+@tab @samp{-}
+@tab No
+
@end multitable
These are the currently defined stub features, in more detail:
The remote stub understands the @samp{qXfer:siginfo:write} packet
(@pxref{qXfer siginfo write}).
+@item qXfer:threads:read
+The remote stub understands the @samp{qXfer:threads:read} packet
+(@pxref{qXfer threads read}).
+
@item QNonStop
The remote stub understands the @samp{QNonStop} packet
(@pxref{QNonStop}).
The remote stub understands the @samp{qXfer:osdata:read} packet
((@pxref{qXfer osdata read}).
+@item ConditionalTracepoints
+The remote stub accepts and implements conditional expressions defined
+for tracepoints (@pxref{Tracepoint Conditions}).
+
+@item ReverseContinue
+The remote stub accepts and implements the reverse continue packet
+(@pxref{bc}).
+
+@item ReverseStep
+The remote stub accepts and implements the reverse step packet
+(@pxref{bs}).
+
@end table
@item qSymbol::
(if available), until the target ceases to request them.
@end table
-@item QTDP
+@item qTBuffer
+@item QTDisconnected
+@itemx QTDP
+@itemx QTDV
+@itemx qTfP
+@itemx qTfV
@itemx QTFrame
@xref{Tracepoint Packets}.
conventions above. Please don't use this packet as a model for new
packets.)
-@item QTStart
+@item QTSave
+@item qTsP
+@item qTsV
+@itemx QTStart
@itemx QTStop
@itemx QTinit
@itemx QTro
@itemx qTStatus
+@itemx qTV
@xref{Tracepoint Packets}.
@item qXfer:@var{object}:read:@var{annex}:@var{offset},@var{length}
by supplying an appropriate @samp{qSupported} response
(@pxref{qSupported}).
+@item qXfer:threads:read::@var{offset},@var{length}
+@anchor{qXfer threads read}
+Access the list of threads on target. @xref{Thread List Format}. The
+annex part of the generic @samp{qXfer} packet must be empty
+(@pxref{qXfer read}).
+
+This packet is not probed by default; the remote stub must request it,
+by supplying an appropriate @samp{qSupported} response (@pxref{qSupported}).
+
@item qXfer:osdata:read::@var{offset},@var{length}
@anchor{qXfer osdata read}
Access the target's @dfn{operating system information}.
@end table
-@node Register Packet Format
-@section Register Packet Format
+@node Architecture-Specific Protocol Details
+@section Architecture-Specific Protocol Details
+
+This section describes how the remote protocol is applied to specific
+target architectures. Also see @ref{Standard Target Features}, for
+details of XML target descriptions for each architecture.
+
+@subsection ARM
+
+@subsubsection Breakpoint Kinds
+
+These breakpoint kinds are defined for the @samp{Z0} and @samp{Z1} packets.
+
+@table @r
+
+@item 2
+16-bit Thumb mode breakpoint.
+
+@item 3
+32-bit Thumb mode (Thumb-2) breakpoint.
+
+@item 4
+32-bit ARM mode breakpoint.
+
+@end table
+
+@subsection MIPS
+
+@subsubsection Register Packet Format
The following @code{g}/@code{G} packets have previously been defined.
In the below, some thirty-two bit registers are transferred as
@table @samp
-@item QTDP:@var{n}:@var{addr}:@var{ena}:@var{step}:@var{pass}@r{[}-@r{]}
+@item QTDP:@var{n}:@var{addr}:@var{ena}:@var{step}:@var{pass}[:F@var{flen}][:X@var{len},@var{bytes}]@r{[}-@r{]}
Create a new tracepoint, number @var{n}, at @var{addr}. If @var{ena}
is @samp{E}, then the tracepoint is enabled; if it is @samp{D}, then
the tracepoint is disabled. @var{step} is the tracepoint's step
-count, and @var{pass} is its pass count. If the trailing @samp{-} is
-present, further @samp{QTDP} packets will follow to specify this
-tracepoint's actions.
+count, and @var{pass} is its pass count. If an @samp{F} is present,
+then the tracepoint is to be a fast tracepoint, and the @var{flen} is
+the number of bytes that the target should copy elsewhere to make room
+for the tracepoint. If an @samp{X} is present, it introduces a
+tracepoint condition, which consists of a hexadecimal length, followed
+by a comma and hex-encoded bytes, in a manner similar to action
+encodings as described below. If the trailing @samp{-} is present,
+further @samp{QTDP} packets will follow to specify this tracepoint's
+actions.
Replies:
@table @samp
The packet was not recognized.
@end table
+@item QTDV:@var{n}:@var{value}
+@cindex define trace state variable, remote request
+@cindex @samp{QTDV} packet
+Create a new trace state variable, number @var{n}, with an initial
+value of @var{value}, which is a 64-bit signed integer. Both @var{n}
+and @var{value} are encoded as hexadecimal values. @value{GDBN} has
+the option of not using this packet for initial values of zero; the
+target should simply create the trace state variables as they are
+mentioned in expressions.
+
@item QTFrame:@var{n}
Select the @var{n}'th tracepoint frame from the buffer, and use the
register and memory contents recorded there to answer subsequent
still have the same contents they did when the tracepoint was hit, so
there's no reason for the stub to refuse to provide their contents.
+@item QTDisconnected:@var{value}
+Set the choice to what to do with the tracing run when @value{GDBN}
+disconnects from the target. A @var{value} of 1 directs the target to
+continue the tracing run, while 0 tells the target to stop tracing if
+@value{GDBN} is no longer in the picture.
+
@item qTStatus
Ask the stub if there is a trace experiment running right now.
There is a trace experiment running.
@end table
-@end table
+@item qTV:@var{var}
+@cindex trace state variable value, remote request
+@cindex @samp{qTV} packet
+Ask the stub for the value of the trace state variable number @var{var}.
+
+Replies:
+@table @samp
+@item V@var{value}
+The value of the variable is @var{value}. This will be the current
+value of the variable if the user is examining a running target, or a
+saved value if the variable was collected in the trace frame that the
+user is looking at. Note that multiple requests may result in
+different reply values, such as when requesting values while the
+program is running.
+
+@item U
+The value of the variable is unknown. This would occur, for example,
+if the user is examining a trace frame in which the requested variable
+was not collected.
+@end table
+
+@item qTfP
+@itemx qTsP
+These packets request data about tracepoints that are being used by
+the target. @value{GDBN} sends @code{qTfP} to get the first piece
+of data, and multiple @code{qTsP} to get additional pieces. Replies
+to these packets generally take the form of the @code{QTDP} packets
+that define tracepoints. (FIXME add detailed syntax)
+
+@item qTfV
+@itemx qTsV
+These packets request data about trace state variables that are on the
+target. @value{GDBN} sends @code{qTfV} to get the first vari of data,
+and multiple @code{qTsV} to get additional variables. Replies to
+these packets follow the syntax of the @code{QTDV} packets that define
+trace state variables.
+
+@item QTSave:@var{filename}
+This packet directs the target to save trace data to the file name
+@var{filename} in the target's filesystem. @var{filename} is encoded
+as a hex string; the interpretation of the file name (relative vs
+absolute, wild cards, etc) is up to the target.
+
+@item qTBuffer:@var{offset},@var{len}
+Return up to @var{len} bytes of the current contents of trace buffer,
+starting at @var{offset}. The trace buffer is treated as if it were
+a contiguous collection of traceframes, as per the trace file format.
+The reply consists as many hex-encoded bytes as the target can deliver
+in a packet; it is not an error to return fewer than were asked for.
+A reply consisting of just @code{l} indicates that no bytes are
+available.
+@end table
@node Host I/O Packets
@section Host I/O Packets
@cindex interrupts (remote protocol)
When a program on the remote target is running, @value{GDBN} may
-attempt to interrupt it by sending a @samp{Ctrl-C} or a @code{BREAK},
-control of which is specified via @value{GDBN}'s @samp{remotebreak}
-setting (@pxref{set remotebreak}).
+attempt to interrupt it by sending a @samp{Ctrl-C}, @code{BREAK} or
+a @code{BREAK} followed by @code{g},
+control of which is specified via @value{GDBN}'s @samp{interrupt-sequence}.
The precise meaning of @code{BREAK} is defined by the transport
mechanism and may, in fact, be undefined. @value{GDBN} does not
(@pxref{X packet}), used for binary downloads, may include an unescaped
@code{0x03} as part of its packet.
+@code{BREAK} followed by @code{g} is also known as Magic SysRq g.
+When Linux kernel receives this sequence from serial port,
+it stops execution and connects to gdb.
+
Stubs are not required to recognize these interrupt mechanisms and the
precise meaning associated with receipt of the interrupt is
implementation defined. If the target supports debugging of multiple
<!ATTLIST property name CDATA #REQUIRED>
@end smallexample
+@node Thread List Format
+@section Thread List Format
+@cindex thread list format
+
+To efficiently update the list of threads and their attributes,
+@value{GDBN} issues the @samp{qXfer:threads:read} packet
+(@pxref{qXfer threads read}) and obtains the XML document with
+the following structure:
+
+@smallexample
+<?xml version="1.0"?>
+<threads>
+ <thread id="id" core="0">
+ ... description ...
+ </thread>
+</threads>
+@end smallexample
+
+Each @samp{thread} element must have the @samp{id} attribute that
+identifies the thread (@pxref{thread-id syntax}). The
+@samp{core} attribute, if present, specifies which processor core
+the thread was last executing on. The content of the of @samp{thread}
+element is interpreted as human-readable auxilliary information.
+
@include agentexpr.texi
+@node Trace File Format
+@appendix Trace File Format
+@cindex trace file format
+
+The trace file comes in three parts: a header, a textual description
+section, and a trace frame section with binary data.
+
+The header has the form @code{\x7fTRACE0\n}. The first byte is
+@code{0x7f} so as to indicate that the file contains binary data,
+while the @code{0} is a version number that may have different values
+in the future.
+
+The description section consists of multiple lines of @sc{ascii} text
+separated by newline characters (@code{0xa}). The lines may include a
+variety of optional descriptive or context-setting information, such
+as tracepoint definitions or register set size. @value{GDBN} will
+ignore any line that it does not recognize. An empty line marks the end
+of this section.
+
+@c FIXME add some specific types of data
+
+The trace frame section consists of a number of consecutive frames.
+Each frame begins with a two-byte tracepoint number, followed by a
+four-byte size giving the amount of data in the frame. The data in
+the frame consists of a number of blocks, each introduced by a
+character indicating its type (at least register, memory, and trace
+state variable). The data in this section is raw binary, not a
+hexadecimal or other encoding; its endianness matches the target's
+endianness.
+
+@c FIXME bi-arch may require endianness/arch info in description section
+
+@table @code
+@item R @var{bytes}
+Register block. The number and ordering of bytes matches that of a
+@code{g} packet in the remote protocol. Note that these are the
+actual bytes, in target order and @value{GDBN} register order, not a
+hexadecimal encoding.
+
+@item M @var{address} @var{length} @var{bytes}...
+Memory block. This is a contiguous block of memory, at the 8-byte
+address @var{address}, with a 2-byte length @var{length}, followed by
+@var{length} bytes.
+
+@item V @var{number} @var{value}
+Trace state variable block. This records the 8-byte signed value
+@var{value} of trace state variable numbered @var{number}.
+
+@end table
+
+Future enhancements of the trace file format may include additional types
+of blocks.
+
@node Target Descriptions
@appendix Target Descriptions
@cindex target descriptions
Target descriptions can identify the architecture of the remote target
and (for some architectures) provide information about custom register
-sets. @value{GDBN} can use this information to autoconfigure for your
+sets. They can also identify the OS ABI of the remote target.
+@value{GDBN} can use this information to autoconfigure for your
target, or to warn you if you connect to an unsupported target.
Here is a simple target description:
<!DOCTYPE target SYSTEM "gdb-target.dtd">
<target version="1.0">
@r{[}@var{architecture}@r{]}
+ @r{[}@var{osabi}@r{]}
+ @r{[}@var{compatible}@r{]}
@r{[}@var{feature}@dots{}@r{]}
</target>
@end smallexample
<architecture>@var{arch}</architecture>
@end smallexample
-@var{arch} is an architecture name from the same selection
-accepted by @code{set architecture} (@pxref{Targets, ,Specifying a
-Debugging Target}).
+@var{arch} is one of the architectures from the set accepted by
+@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
+
+@subsection OS ABI
+@cindex @code{<osabi>}
+
+This optional field was introduced in @value{GDBN} version 7.0.
+Previous versions of @value{GDBN} ignore it.
+
+An @samp{<osabi>} element has this form:
+
+@smallexample
+ <osabi>@var{abi-name}</osabi>
+@end smallexample
+
+@var{abi-name} is an OS ABI name from the same selection accepted by
+@w{@code{set osabi}} (@pxref{ABI, ,Configuring the Current ABI}).
+
+@subsection Compatible Architecture
+@cindex @code{<compatible>}
+
+This optional field was introduced in @value{GDBN} version 7.0.
+Previous versions of @value{GDBN} ignore it.
+
+A @samp{<compatible>} element has this form:
+
+@smallexample
+ <compatible>@var{arch}</compatible>
+@end smallexample
+
+@var{arch} is one of the architectures from the set accepted by
+@code{set architecture} (@pxref{Targets, ,Specifying a Debugging Target}).
+
+A @samp{<compatible>} element is used to specify that the target
+is able to run binaries in some other than the main target architecture
+given by the @samp{<architecture>} element. For example, on the
+Cell Broadband Engine, the main architecture is @code{powerpc:common}
+or @code{powerpc:common64}, but the system is able to run binaries
+in the @code{spu} architecture as well. The way to describe this
+capability with @samp{<compatible>} is as follows:
+
+@smallexample
+ <architecture>powerpc:common</architecture>
+ <compatible>spu</compatible>
+@end smallexample
@subsection Features
@cindex <feature>
@samp{wCGR0} through @samp{wCGR3}. The @samp{wCID}, @samp{wCon},
@samp{wCSSF}, and @samp{wCASF} registers are optional.
+The @samp{org.gnu.gdb.arm.vfp} feature is optional. If present, it
+should contain at least registers @samp{d0} through @samp{d15}. If
+they are present, @samp{d16} through @samp{d31} should also be included.
+@value{GDBN} will synthesize the single-precision registers from
+halves of the double-precision registers.
+
+The @samp{org.gnu.gdb.arm.neon} feature is optional. It does not
+need to contain registers; it instructs @value{GDBN} to display the
+VFP double-precision registers as vectors and to synthesize the
+quad-precision registers from pairs of double-precision registers.
+If this feature is present, @samp{org.gnu.gdb.arm.vfp} must also
+be present and include 32 double-precision registers.
+
@node MIPS Features
@subsection MIPS Features
@cindex target descriptions, MIPS features
<column name="pid">1</column>
<column name="user">root</column>
<column name="command">/sbin/init</column>
+ <column name="cores">1,2,3</column>
</item>
</osdata>
@end smallexample
Each item should include a column whose name is @samp{pid}. The value
of that column should identify the process on the target. The
@samp{user} and @samp{command} columns are optional, and will be
-displayed by @value{GDBN}. Target may provide additional columns,
+displayed by @value{GDBN}. The @samp{cores} column, if present,
+should contain a comma-separated list of cores that this process
+is running on. Target may provide additional columns,
which @value{GDBN} currently ignores.
@include gpl.texi
projects / deliverable / binutils-gdb.git / blobdiff