The search path is used to find both program source files and @value{GDBN}
script files (read using the @samp{-command} option and @samp{source} command).
+In addition to the source path, @value{GDBN} provides a set of commands
+that manage a list of source path substitution rules. A @dfn{substitution
+rule} specifies how to rewrite source directories stored in the program's
+debug information in case the sources were moved to a different
+directory between compilation and debugging. A rule is made of
+two strings, the first specifying what needs to be rewritten in
+the path, and the second specifying how it should be rewritten.
+In @ref{set substitute-path}, we name these two parts @var{from} and
+@var{to} respectively. @value{GDBN} does a simple string replacement
+of @var{from} with @var{to} at the start of the directory part of the
+source file name, and uses that result instead of the original file
+name to look up the sources.
+
+Using the previous example, suppose the @file{foo-1.0} tree has been
+moved from @file{/usr/src} to @file{/mnt/cross}, then you can tell
+GDB to replace @file{/usr/src} in all source path names with
+@file{/mnt/cross}. The first lookup will then be
+@file{/mnt/cross/foo-1.0/lib/foo.c} in place of the original location
+of @file{/usr/src/foo-1.0/lib/foo.c}. To define a source path
+substitution rule, use the @code{set substitute-path} command
+(@pxref{set substitute-path}).
+
+To avoid unexpected substitution results, a rule is applied only if the
+@var{from} part of the directory name ends at a directory separator.
+For instance, a rule substituting @file{/usr/source} into
+@file{/mnt/cross} will be applied to @file{/usr/source/foo-1.0} but
+not to @file{/usr/sourceware/foo-2.0}. And because the substitution
+is applied only at the begining of the directory name, this rule will
+not be applied to @file{/root/usr/source/baz.c} either.
+
+In many cases, you can achieve the same result using the @code{directory}
+command. However, @code{set substitute-path} can be more efficient in
+the case where the sources are organized in a complex tree with multiple
+subdirectories. With the @code{directory} command, you need to add each
+subdirectory of your project. If you moved the entire tree while
+preserving its internal organization, then @code{set substitute-path}
+allows you to direct the debugger to all the sources with one single
+command.
+
+@code{set substitute-path} is also more than just a shortcut command.
+The source path is only used if the file at the original location no
+longer exists. On the other hand, @code{set substitute-path} modifies
+the debugger behavior to look at the rewritten location instead. So, if
+for any reason a source file that is not relevant to your executable is
+located at the original location, a substitution rule is the only
+method available to point GDB at the new location.
+
@table @code
@item directory @var{dirname} @dots{}
@item dir @var{dirname} @dots{}
@item show directories
@kindex show directories
Print the source path: show which directories it contains.
+
+@anchor{set substitute-path}
+@item set substitute-path @var{from} @var{to}
+@kindex set substitute-path
+Define a source path substitution rule, and add it at the end of the
+current list of existing substitution rules. If a rule with the same
+@var{from} was already defined, then the old rule is also deleted.
+
+For example, if the file @file{/foo/bar/baz.c} was moved to
+@file{/mnt/cross/baz.c}, then the command
+
+@smallexample
+(@value{GDBP}) set substitute-path /usr/src /mnt/cross
+@end smallexample
+
+@noindent
+will tell @value{GDBN} to replace @samp{/usr/src} with
+@samp{/mnt/cross}, which will allow @value{GDBN} to find the file
+@file{baz.c} even though it was moved.
+
+In the case when more than one substitution rule have been defined,
+the rules are evaluated one by one in the order where they have been
+defined. The first one matching, if any, is selected to perform
+the substitution.
+
+For instance, if we had entered the following commands:
+
+@smallexample
+(@value{GDBP}) set substitute-path /usr/src/include /mnt/include
+(@value{GDBP}) set substitute-path /usr/src /mnt/src
+@end smallexample
+
+@noindent
+@value{GDBN} would then rewrite @file{/usr/src/include/defs.h} into
+@file{/mnt/include/defs.h} by using the first rule. However, it would
+use the second rule to rewrite @file{/usr/src/lib/foo.c} into
+@file{/mnt/src/lib/foo.c}.
+
+
+@item unset substitute-path [path]
+@kindex unset substitute-path
+If a path is specified, search the current list of substitution rules
+for a rule that would rewrite that path. Delete that rule if found.
+A warning is emitted by the debugger if no rule could be found.
+
+If no path is specified, then all substitution rules are deleted.
+
+@item show substitute-path [path]
+@kindex show substitute-path
+If a path is specified, then print the source path substitution rule
+which would rewrite that path, if any.
+
+If no path is specified, then print all existing source path substitution
+rules.
+
@end table
If your source path is cluttered with directories that are no longer of
Many remote targets require you to download the executable's code once
you've successfully established a connection. You may wish to control
-various aspects of this process, such as the size of the data chunks
-used by @value{GDBN} to download program parts to the remote target.
+various aspects of this process.
@table @code
-@kindex set download-write-size
-@item set download-write-size @var{size}
-Set the write size used when downloading a program. Only used when
-downloading a program onto a remote target. Specify zero or a
-negative value to disable blocked writes. The actual size of each
-transfer is also limited by the size of the target packet and the
-memory cache.
-
-@kindex show download-write-size
-@item show download-write-size
-@kindex show download-write-size
-Show the current value of the write size.
@item set hash
@kindex set hash@r{, for remote monitors}
@end table
+@cindex command tracing
+If you need to debug user-defined commands or sourced files you may find it
+useful to enable @dfn{command tracing}. In this mode each command will be
+printed as it is executed, prefixed with one or more @samp{+} symbols, the
+quantity denoting the call depth of each command.
+
+@table @code
+@kindex set trace-commands
+@cindex command scripts, debugging
+@item set trace-commands on
+Enable command tracing.
+@item set trace-commands off
+Disable command tracing.
+@item show trace-commands
+Display the current state of command tracing.
+@end table
+
@node Debugging Output
@section Optional messages about internal happenings
@cindex optional debugging messages
@table @code
@kindex source
@cindex execute commands from a file
-@item source @var{filename}
+@item source [@code{-v}] @var{filename}
Execute the command file @var{filename}.
@end table
@value{GDBN} searches for @var{filename} in the current directory and then
on the search path (specified with the @samp{directory} command).
+If @code{-v}, for verbose mode, is given then @value{GDBN} displays
+each command as it is executed. The option must be given before
+@var{filename}, and is interpreted as part of the filename anywhere else.
+
Commands that would ask for confirmation if used interactively proceed
without asking when used in a command file. Many @value{GDBN} commands that
normally print messages to say what they are doing omit the messages
@node Installing GDB
@appendix Installing @value{GDBN}
-@cindex configuring @value{GDBN}
@cindex installation
-@cindex configuring @value{GDBN}, and source tree subdirectories
+@menu
+* Requirements:: Requirements for building @value{GDBN}
+* Running Configure:: Invoking the @value{GDBN} @code{configure} script
+* Separate Objdir:: Compiling @value{GDBN} in another directory
+* Config Names:: Specifying names for hosts and targets
+* Configure Options:: Summary of options for configure
+@end menu
+
+@node Requirements
+@section Requirements for building @value{GDBN}
+@cindex building @value{GDBN}, requirements for
+
+Building @value{GDBN} requires various tools and packages to be available.
+Other packages will be used only if they are found.
+
+@heading Tools/packages necessary for building @value{GDBN}
+@table @asis
+@item ISO C90 compiler
+@value{GDBN} is written in ISO C90. It should be buildable with any
+working C90 compiler, e.g.@: GCC.
+
+@end table
+
+@heading Tools/packages optional for building @value{GDBN}
+@table @asis
+@item Expat
+@value{GDBN} can use the Expat XML parsing library. This library may be
+included with your operating system distribution; if it is not, you
+can get the latest version from @url{http://expat.sourceforge.net}.
+The @code{configure} script will search for this library in several
+standard locations; if it is installed in an unusual path, you can
+use the @option{--with-libexpat-prefix} option to specify its location.
+
+Expat is used currently only used to implement some remote-specific
+features.
+
+@end table
+
+@node Running Configure
+@section Invoking the @value{GDBN} @code{configure} script
+@cindex configuring @value{GDBN}
@value{GDBN} comes with a @code{configure} script that automates the process
of preparing @value{GDBN} for installation; you can then use @code{make} to
build the @code{gdb} program.
that @value{GDBN} uses the shell to start your program---some systems refuse to
let @value{GDBN} debug child processes whose programs are not readable.
-@menu
-* Separate Objdir:: Compiling @value{GDBN} in another directory
-* Config Names:: Specifying names for hosts and targets
-* Configure Options:: Summary of options for configure
-@end menu
-
@node Separate Objdir
@section Compiling @value{GDBN} in another directory
@item S @var{AA}
The program received signal number @var{AA} (a two-digit hexidecimal
-number).
+number). This is equivalent to a @samp{T} response with no
+@var{n}:@var{r} pairs.
@item T @var{AA} @var{n1}:@var{r1};@var{n2}:@var{r2};@dots{}
@cindex @samp{T} packet reply
The program received signal number @var{AA} (a two-digit hexidecimal
-number). Single-step and breakpoint traps are reported this way. The
-@samp{@var{n}:@var{r}} pairs give the values of important registers or
-other information:
+number). This is equivalent to an @samp{S} response, except that the
+@samp{@var{n}:@var{r}} pairs can carry values of important registers
+and other information directly in the stop reply packet, reducing
+round-trip latency. Single-step and breakpoint traps are reported
+this way. Each @samp{@var{n}:@var{r}} pair is interpreted as follows:
@enumerate
@item
If @var{n} is a hexidecimal number, it is a register number, and the
projects / deliverable / binutils-gdb.git / blobdiff