What has changed in GDB?
(Organized release by release)
-*** Changes since GDB 7.2
+*** Changes since GDB 7.4
+
+* GDB now supports access to MIPS DSP registers on Linux targets.
+
+* GDB now supports debugging microMIPS binaries.
+
+* The "info os" command on GNU/Linux can now display information on
+ several new classes of objects managed by the operating system:
+ "info os procgroups" lists process groups
+ "info os files" lists file descriptors
+ "info os sockets" lists internet-domain sockets
+ "info os shm" lists shared-memory regions
+ "info os semaphores" lists semaphores
+ "info os msg" lists message queues
+ "info os modules" lists loaded kernel modules
+
+* GDB now has support for SDT (Static Defined Tracing) probes. Currently,
+ the only implemented backend is for SystemTap probes (<sys/sdt.h>). You
+ can set a breakpoint using the new "-probe, "-pstap" or "-probe-stap"
+ options and inspect the probe arguments using the new $_probe_arg family
+ of convenience variables. You can obtain more information about SystemTap
+ in <http://sourceware.org/systemtap/>.
+
+* GDB now supports reversible debugging on ARM, it allows you to
+ debug basic ARM and THUMB instructions, and provides
+ record/replay support.
+
+* The option "symbol-reloading" has been deleted as it is no longer used.
+
+* Python scripting
+
+ ** GDB commands implemented in Python can now be put in command class
+ "gdb.COMMAND_USER".
+
+ ** The "maint set python print-stack on|off" is now deleted.
+
+ ** A new class, gdb.printing.FlagEnumerationPrinter, can be used to
+ apply "flag enum"-style pretty-printing to any enum.
+
+ ** gdb.lookup_symbol can now work when there is no current frame.
+
+ ** gdb.Symbol now has a 'line' attribute, holding the line number in
+ the source at which the symbol was defined.
+
+ ** gdb.Symbol now has the new attribute 'needs_frame' and the new
+ method 'value'. The former indicates whether the symbol needs a
+ frame in order to compute its value, and the latter computes the
+ symbol's value.
+
+ ** A new method 'referenced_value' on gdb.Value objects which can
+ dereference pointer as well as C++ reference values.
+
+ ** New methods 'global_block' and 'static_block' on gdb.Symtab objects
+ which return the global and static blocks (as gdb.Block objects),
+ of the underlying symbol table, respectively.
+
+ ** New function gdb.find_pc_line which returns the gdb.Symtab_and_line
+ object associated with a PC value.
+
+* Go language support.
+ GDB now supports debugging programs written in the Go programming
+ language.
+
+* GDBserver now supports stdio connections.
+ E.g. (gdb) target remote | ssh myhost gdbserver - hello
+
+* The binary "gdbtui" can no longer be built or installed.
+ Use "gdb -tui" instead.
+
+* GDB will now print "flag" enums specially. A flag enum is one where
+ all the enumerator values have no bits in common when pairwise
+ "and"ed. When printing a value whose type is a flag enum, GDB will
+ show all the constants, e.g., for enum E { ONE = 1, TWO = 2}:
+ (gdb) print (enum E) 3
+ $1 = (ONE | TWO)
+
+* The filename part of a linespec will now match trailing components
+ of a source file name. For example, "break gcc/expr.c:1000" will
+ now set a breakpoint in build/gcc/expr.c, but not
+ build/libcpp/expr.c.
+
+* The "info proc" and "generate-core-file" commands will now also
+ work on remote targets connected to GDBserver on Linux.
+
+* The command "info catch" has been removed. It has been disabled
+ since December 2007.
+
+* The "catch exception" and "catch assert" commands now accept
+ a condition at the end of the command, much like the "break"
+ command does. For instance:
+
+ (gdb) catch exception Constraint_Error if Barrier = True
+
+ Previously, it was possible to add a condition to such catchpoints,
+ but it had to be done as a second step, after the catchpoint had been
+ created, using the "condition" command.
+
+* The "info static-tracepoint-marker" command will now also work on
+ native Linux targets with in-process agent.
+
+* GDB can now set breakpoints on inlined functions.
+
+* The .gdb_index section has been updated to include symbols for
+ inlined functions. GDB will ignore older .gdb_index sections by
+ default, which could cause symbol files to be loaded more slowly
+ until their .gdb_index sections can be recreated. The new option
+ --use-deprecated-index-sections will cause GDB to use any older
+ .gdb_index sections it finds. This will restore performance, but
+ the ability to set breakpoints on inlined functions will be lost
+ in symbol files with older .gdb_index sections.
+
+ The .gdb_index section has also been updated to record more information
+ about each symbol. This speeds up the "info variables", "info functions"
+ and "info types" commands when used with programs having the .gdb_index
+ section, as well as speeding up debugging with shared libraries using
+ the .gdb_index section.
+
+* Ada support for GDB/MI Variable Objects has been added.
+
+* GDB can now support 'breakpoint always-inserted mode' in 'record'
+ target.
+
+* MI changes
+
+ ** New command -info-os is the MI equivalent of "info os".
+
+* New commands
+
+ ** "catch load" and "catch unload" can be used to stop when a shared
+ library is loaded or unloaded, respectively.
+
+ ** "enable count" can be used to auto-disable a breakpoint after
+ several hits.
+
+ ** "info vtbl" can be used to show the virtual method tables for
+ C++ and Java objects.
+
+ ** "explore" and its sub commands "explore value" and "explore type"
+ can be used to reccursively explore values and types of
+ expressions. These commands are available only if GDB is
+ configured with '--with-python'.
+
+ ** "info auto-load" shows status of all kinds of auto-loaded files,
+ "info auto-load gdb-scripts" shows status of auto-loading GDB canned
+ sequences of commands files, "info auto-load python-scripts"
+ shows status of auto-loading Python script files,
+ "info auto-load local-gdbinit" shows status of loading init file
+ (.gdbinit) from current directory and "info auto-load libthread-db" shows
+ status of inferior specific thread debugging shared library loading.
+
+ ** "info auto-load-scripts", "set auto-load-scripts on|off"
+ and "show auto-load-scripts" commands have been deprecated, use their
+ "info auto-load python-scripts", "set auto-load python-scripts on|off"
+ and "show auto-load python-scripts" counterparts instead.
+
+ ** "dprintf location,format,args..." creates a dynamic printf, which
+ is basically a breakpoint that does a printf and immediately
+ resumes your program's execution, so it is like a printf that you
+ can insert dynamically at runtime instead of at compiletime.
+
+ ** "set print symbol"
+ "show print symbol"
+ Controls whether GDB attempts to display the symbol, if any,
+ corresponding to addresses it prints. This defaults to "on", but
+ you can set it to "off" to restore GDB's previous behavior.
+
+* Deprecated commands
+
+ ** For the Renesas Super-H architecture, the "regs" command has been
+ deprecated, and "info all-registers" should be used instead.
+
+* New targets
+
+Renesas RL78 rl78-*-elf
+HP OpenVMS ia64 ia64-hp-openvms*
+
+* GDBserver supports evaluation of breakpoint conditions. When
+ support is advertised by GDBserver, GDB may be told to send the
+ breakpoint conditions in bytecode form to GDBserver. GDBserver
+ will only report the breakpoint trigger to GDB when its condition
+ evaluates to true.
+
+* New options
+
+set mips compression
+show mips compression
+ Select the compressed ISA encoding used in functions that have no symbol
+ information available. The encoding can be set to either of:
+ mips16
+ micromips
+ and is updated automatically from ELF file flags if available.
+
+set breakpoint condition-evaluation
+show breakpoint condition-evaluation
+ Control whether breakpoint conditions are evaluated by GDB ("host") or by
+ GDBserver ("target"). Default option "auto" chooses the most efficient
+ available mode.
+ This option can improve debugger efficiency depending on the speed of the
+ target.
+
+set auto-load off
+ Disable auto-loading globally.
+
+show auto-load
+ Show auto-loading setting of all kinds of auto-loaded files.
+
+set auto-load gdb-scripts on|off
+show auto-load gdb-scripts
+ Control auto-loading of GDB canned sequences of commands files.
+
+set auto-load python-scripts on|off
+show auto-load python-scripts
+ Control auto-loading of Python script files.
+
+set auto-load local-gdbinit on|off
+show auto-load local-gdbinit
+ Control loading of init file (.gdbinit) from current directory.
+
+set auto-load libthread-db on|off
+show auto-load libthread-db
+ Control auto-loading of inferior specific thread debugging shared library.
+
+set auto-load scripts-directory <dir1>[:<dir2>...]
+show auto-load scripts-directory
+ Set a list of directories from which to load auto-loaded scripts.
+ Automatically loaded Python scripts and GDB scripts are located in one
+ of the directories listed by this option.
+ The delimiter (':' above) may differ according to the host platform.
+
+set auto-load safe-path <dir1>[:<dir2>...]
+show auto-load safe-path
+ Set a list of directories from which it is safe to auto-load files.
+ The delimiter (':' above) may differ according to the host platform.
+
+set debug auto-load on|off
+show debug auto-load
+ Control display of debugging info for auto-loading the files above.
+
+set dprintf-style gdb|call
+show dprintf-style
+ Control the way in which a dynamic printf is performed; "gdb" requests
+ a GDB printf command, while "call" causes dprintf to call a function
+ in the inferior.
+
+set dprintf-function <expr>
+show dprintf-function
+set dprintf-channel <expr>
+show dprintf-channel
+ Set the function and optional first argument to the call when using
+ the "call" style of dynamic printf.
+
+* New configure options
+
+--with-auto-load-dir
+ Configure default value for the 'set auto-load scripts-directory'
+ setting above. It defaults to '$debugdir:$datadir/auto-load',
+ $debugdir representing global debugging info directories (available
+ via 'show debug-file-directory') and $datadir representing GDB's data
+ directory (available via 'show data-directory').
+
+--with-auto-load-safe-path
+ Configure default value for the 'set auto-load safe-path' setting
+ above. It defaults to the --with-auto-load-dir setting.
+
+--without-auto-load-safe-path
+ Set 'set auto-load safe-path' to '/', effectively disabling this
+ security feature.
+
+* New remote packets
+
+z0/z1 conditional breakpoints extension
+
+ The z0/z1 breakpoint insertion packets have been extended to carry
+ a list of conditional expressions over to the remote stub depending on the
+ condition evaluation mode. The use of this extension can be controlled
+ via the "set remote conditional-breakpoints-packet" command.
+
+QProgramSignals:
+
+ Specify the signals which the remote stub may pass to the debugged
+ program without GDB involvement.
+
+* New command line options
+
+--init-command=FILE, -ix Like --command, -x but execute it
+ before loading inferior.
+--init-eval-command=COMMAND, -iex Like --eval-command=COMMAND, -ex but
+ execute it before loading inferior.
+
+*** Changes in GDB 7.4
+
+* GDB now handles ambiguous linespecs more consistently; the existing
+ FILE:LINE support has been expanded to other types of linespecs. A
+ breakpoint will now be set on all matching locations in all
+ inferiors, and locations will be added or removed according to
+ inferior changes.
+
+* GDB now allows you to skip uninteresting functions and files when
+ stepping with the "skip function" and "skip file" commands.
+
+* GDB has two new commands: "set remote hardware-watchpoint-length-limit"
+ and "show remote hardware-watchpoint-length-limit". These allows to
+ set or show the maximum length limit (in bytes) of a remote
+ target hardware watchpoint.
+
+ This allows e.g. to use "unlimited" hardware watchpoints with the
+ gdbserver integrated in Valgrind version >= 3.7.0. Such Valgrind
+ watchpoints are slower than real hardware watchpoints but are
+ significantly faster than gdb software watchpoints.
+
+* Python scripting
+
+ ** The register_pretty_printer function in module gdb.printing now takes
+ an optional `replace' argument. If True, the new printer replaces any
+ existing one.
+
+ ** The "maint set python print-stack on|off" command has been
+ deprecated and will be deleted in GDB 7.5.
+ A new command: "set python print-stack none|full|message" has
+ replaced it. Additionally, the default for "print-stack" is
+ now "message", which just prints the error message without
+ the stack trace.
+
+ ** A prompt substitution hook (prompt_hook) is now available to the
+ Python API.
+
+ ** A new Python module, gdb.prompt has been added to the GDB Python
+ modules library. This module provides functionality for
+ escape sequences in prompts (used by set/show
+ extended-prompt). These escape sequences are replaced by their
+ corresponding value.
+
+ ** Python commands and convenience-functions located in
+ 'data-directory'/python/gdb/command and
+ 'data-directory'/python/gdb/function are now automatically loaded
+ on GDB start-up.
+
+ ** Blocks now provide four new attributes. global_block and
+ static_block will return the global and static blocks
+ respectively. is_static and is_global are boolean attributes
+ that indicate if the block is one of those two types.
+
+ ** Symbols now provide the "type" attribute, the type of the symbol.
+
+ ** The "gdb.breakpoint" function has been deprecated in favor of
+ "gdb.breakpoints".
+
+ ** A new class "gdb.FinishBreakpoint" is provided to catch the return
+ of a function. This class is based on the "finish" command
+ available in the CLI.
+
+ ** Type objects for struct and union types now allow access to
+ the fields using standard Python dictionary (mapping) methods.
+ For example, "some_type['myfield']" now works, as does
+ "some_type.items()".
+
+ ** A new event "gdb.new_objfile" has been added, triggered by loading a
+ new object file.
+
+ ** A new function, "deep_items" has been added to the gdb.types
+ module in the GDB Python modules library. This function returns
+ an iterator over the fields of a struct or union type. Unlike
+ the standard Python "iteritems" method, it will recursively traverse
+ any anonymous fields.
+
+* MI changes
+
+ ** "*stopped" events can report several new "reason"s, such as
+ "solib-event".
+
+ ** Breakpoint changes are now notified using new async records, like
+ "=breakpoint-modified".
+
+ ** New command -ada-task-info.
+
+* libthread-db-search-path now supports two special values: $sdir and $pdir.
+ $sdir specifies the default system locations of shared libraries.
+ $pdir specifies the directory where the libpthread used by the application
+ lives.
+
+ GDB no longer looks in $sdir and $pdir after it has searched the directories
+ mentioned in libthread-db-search-path. If you want to search those
+ directories, they must be specified in libthread-db-search-path.
+ The default value of libthread-db-search-path on GNU/Linux and Solaris
+ systems is now "$sdir:$pdir".
+
+ $pdir is not supported by gdbserver, it is currently ignored.
+ $sdir is supported by gdbserver.
+
+* New configure option --with-iconv-bin.
+ When using the internationalization support like the one in the GNU C
+ library, GDB will invoke the "iconv" program to get a list of supported
+ character sets. If this program lives in a non-standard location, one can
+ use this option to specify where to find it.
+
+* When natively debugging programs on PowerPC BookE processors running
+ a Linux kernel version 2.6.34 or later, GDB supports masked hardware
+ watchpoints, which specify a mask in addition to an address to watch.
+ The mask specifies that some bits of an address (the bits which are
+ reset in the mask) should be ignored when matching the address accessed
+ by the inferior against the watchpoint address. See the "PowerPC Embedded"
+ section in the user manual for more details.
+
+* The new option --once causes GDBserver to stop listening for connections once
+ the first connection is made. The listening port used by GDBserver will
+ become available after that.
+
+* New commands "info macros" and "alias" have been added.
+
+* New function parameters suffix @entry specifies value of function parameter
+ at the time the function got called. Entry values are available only since
+ gcc version 4.7.
+
+* New commands
+
+!SHELL COMMAND
+ "!" is now an alias of the "shell" command.
+ Note that no space is needed between "!" and SHELL COMMAND.
+
+* Changed commands
+
+watch EXPRESSION mask MASK_VALUE
+ The watch command now supports the mask argument which allows creation
+ of masked watchpoints, if the current architecture supports this feature.
+
+info auto-load-scripts [REGEXP]
+ This command was formerly named "maintenance print section-scripts".
+ It is now generally useful and is no longer a maintenance-only command.
+
+info macro [-all] [--] MACRO
+ The info macro command has new options `-all' and `--'. The first for
+ printing all definitions of a macro. The second for explicitly specifying
+ the end of arguments and the beginning of the macro name in case the macro
+ name starts with a hyphen.
+
+collect[/s] EXPRESSIONS
+ The tracepoint collect command now takes an optional modifier "/s"
+ that directs it to dereference pointer-to-character types and
+ collect the bytes of memory up to a zero byte. The behavior is
+ similar to what you see when you use the regular print command on a
+ string. An optional integer following the "/s" sets a bound on the
+ number of bytes that will be collected.
+
+tstart [NOTES]
+ The trace start command now interprets any supplied arguments as a
+ note to be recorded with the trace run, with an effect similar to
+ setting the variable trace-notes.
+
+tstop [NOTES]
+ The trace stop command now interprets any arguments as a note to be
+ mentioned along with the tstatus report that the trace was stopped
+ with a command. The effect is similar to setting the variable
+ trace-stop-notes.
+
+* Tracepoints can now be enabled and disabled at any time after a trace
+ experiment has been started using the standard "enable" and "disable"
+ commands. It is now possible to start a trace experiment with no enabled
+ tracepoints; GDB will display a warning, but will allow the experiment to
+ begin, assuming that tracepoints will be enabled as needed while the trace
+ is running.
+
+* Fast tracepoints on 32-bit x86-architectures can now be placed at
+ locations with 4-byte instructions, when they were previously
+ limited to locations with instructions of 5 bytes or longer.
+
+* New options
+
+set extended-prompt
+show extended-prompt
+ Set the GDB prompt, and allow escape sequences to be inserted to
+ display miscellaneous information (see 'help set extended-prompt'
+ for the list of sequences). This prompt (and any information
+ accessed through the escape sequences) is updated every time the
+ prompt is displayed.
+
+set print entry-values (both|compact|default|if-needed|no|only|preferred)
+show print entry-values
+ Set printing of frame argument values at function entry. In some cases
+ GDB can determine the value of function argument which was passed by the
+ function caller, even if the value was modified inside the called function.
+
+set debug entry-values
+show debug entry-values
+ Control display of debugging info for determining frame argument values at
+ function entry and virtual tail call frames.
+
+set basenames-may-differ
+show basenames-may-differ
+ Set whether a source file may have multiple base names.
+ (A "base name" is the name of a file with the directory part removed.
+ Example: The base name of "/home/user/hello.c" is "hello.c".)
+ If set, GDB will canonicalize file names (e.g., expand symlinks)
+ before comparing them. Canonicalization is an expensive operation,
+ but it allows the same file be known by more than one base name.
+ If not set (the default), all source files are assumed to have just
+ one base name, and gdb will do file name comparisons more efficiently.
+
+set trace-user
+show trace-user
+set trace-notes
+show trace-notes
+ Set a user name and notes for the current and any future trace runs.
+ This is useful for long-running and/or disconnected traces, to
+ inform others (or yourself) as to who is running the trace, supply
+ contact information, or otherwise explain what is going on.
+
+set trace-stop-notes
+show trace-stop-notes
+ Set a note attached to the trace run, that is displayed when the
+ trace has been stopped by a tstop command. This is useful for
+ instance as an explanation, if you are stopping a trace run that was
+ started by someone else.
+
+* New remote packets
+
+QTEnable
+
+ Dynamically enable a tracepoint in a started trace experiment.
+
+QTDisable
+
+ Dynamically disable a tracepoint in a started trace experiment.
+
+QTNotes
+
+ Set the user and notes of the trace run.
+
+qTP
+
+ Query the current status of a tracepoint.
+
+qTMinFTPILen
+
+ Query the minimum length of instruction at which a fast tracepoint may
+ be placed.
+
+* Dcache size (number of lines) and line-size are now runtime-configurable
+ via "set dcache line" and "set dcache line-size" commands.
+
+* New targets
+
+Texas Instruments TMS320C6x tic6x-*-*
+
+* New Simulators
+
+Renesas RL78 rl78-*-elf
+
+*** Changes in GDB 7.3.1
+
+* The build failure for NetBSD and OpenBSD targets have now been fixed.
+
+*** Changes in GDB 7.3
* GDB has a new command: "thread find [REGEXP]".
It finds the thread id whose name, target id, or thread extra info
* Python scripting
+ ** The function gdb.Write now accepts an optional keyword 'stream'.
+ This keyword, when provided, will direct the output to either
+ stdout, stderr, or GDB's logging output.
+
** Parameters can now be be sub-classed in Python, and in particular
you may implement the get_set_doc and get_show_doc functions.
This improves how Parameter set/show documentation is processed
and allows for more dynamic content.
+ ** Symbols, Symbol Table, Symbol Table and Line, Object Files,
+ Inferior, Inferior Thread, Blocks, and Block Iterator APIs now
+ have an is_valid method.
+
** Breakpoints can now be sub-classed in Python, and in particular
you may implement a 'stop' function that is executed each time
the inferior reaches that breakpoint.
libthread_db library with the "set libthread-db-search-path"
command. See the user manual for more details on this command.
+* When natively debugging programs on PowerPC BookE processors running
+ a Linux kernel version 2.6.34 or later, GDB supports ranged breakpoints,
+ which stop execution of the inferior whenever it executes an instruction
+ at any address within the specified range. See the "PowerPC Embedded"
+ section in the user manual for more details.
+
* New features in the GDB remote stub, GDBserver
** GDBserver is now supported on PowerPC LynxOS (versions 4.x and 5.x),
** The --map-info flag lists all known core mappings.
+ ** CFI flashes may be simulated via the "cfi" device.
+
*** Changes in GDB 7.2
* Shared library support for remote targets by default