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                What has changed in GDB?

             (Organized release by release)

*** Changes in GDB 7.2

* Shared library support for remote targets by default

  When GDB is configured for a generic, non-OS specific target, like

  for example, --target=arm-eabi or one of the many *-*-elf targets,

  GDB now queries remote stubs for loaded shared libraries using the

  `qXfer:libraries:read' packet.  Previously, shared library support

  was always disabled for such configurations.

* C++ Improvements:

  ** Argument Dependent Lookup (ADL)

  In C++ ADL lookup directs function search to the namespaces of its

  arguments even if the namespace has not been imported.

  For example:

    namespace A

      {

        class B { };

        void foo (B) { }

      }

    ...

    A::B b

    foo(b)

  Here the compiler will search for `foo' in the namespace of 'b'

  and find A::foo.  GDB now supports this.  This construct is commonly

  used in the Standard Template Library for operators.

  ** Improved User Defined Operator Support

  In addition to member operators, GDB now supports lookup of operators

  defined in a namespace and imported with a `using' directive, operators

  defined in the global scope, operators imported implicitly from an

  anonymous namespace, and the ADL operators mentioned in the previous

  entry.

  GDB now also supports proper overload resolution for all the previously

  mentioned flavors of operators.

  ** static const class members

  Printing of static const class members that are initialized in the

  class definition has been fixed.

* Windows Thread Information Block access.

  On Windows targets, GDB now supports displaying the Windows Thread

  Information Block (TIB) structure.  This structure is visible either

  by using the new command `info w32 thread-information-block' or, by

  dereferencing the new convenience variable named `$_tlb', a

  thread-specific pointer to the TIB.  This feature is also supported

  when remote debugging using GDBserver.

* Static tracepoints

  Static tracepoints are calls in the user program into a tracing

  library.  One such library is a port of the LTTng kernel tracer to

  userspace --- UST (LTTng Userspace Tracer, http://lttng.org/ust).

  When debugging with GDBserver, GDB now supports combining the GDB

  tracepoint machinery with such libraries.  For example: the user can

  use GDB to probe a static tracepoint marker (a call from the user

  program into the tracing library) with the new "strace" command (see

  "New commands" below).  This creates a "static tracepoint" in the

  breakpoint list, that can be manipulated with the same feature set

  as fast and regular tracepoints.  E.g., collect registers, local and

  global variables, collect trace state variables, and define

  tracepoint conditions.  In addition, the user can collect extra

  static tracepoint marker specific data, by collecting the new

  $_sdata internal variable.  When analyzing the trace buffer, you can

  inspect $_sdata like any other variable available to GDB.  For more

  information, see the "Tracepoints" chapter in GDB user manual.  New

  remote packets have been defined to support static tracepoints, see

  the "New remote packets" section below.

* Better reconstruction of tracepoints after disconnected tracing

  GDB will attempt to download the original source form of tracepoint

  definitions when starting a trace run, and then will upload these

  upon reconnection to the target, resulting in a more accurate

  reconstruction of the tracepoints that are in use on the target.

* Observer mode

  You can now exercise direct control over the ways that GDB can

  affect your program.  For instance, you can disallow the setting of

  breakpoints, so that the program can run continuously (assuming

  non-stop mode).  In addition, the "observer" variable is available

  to switch all of the different controls; in observer mode, GDB

  cannot affect the target's behavior at all, which is useful for

  tasks like diagnosing live systems in the field.

* The new convenience variable $_thread holds the number of the

  current thread.

* New remote packets

qGetTIBAddr

  Return the address of the Windows Thread Information Block of a given thread.

qRelocInsn

  In response to several of the tracepoint packets, the target may now

  also respond with a number of intermediate `qRelocInsn' request

  packets before the final result packet, to have GDB handle

  relocating an instruction to execute at a different address.  This

  is particularly useful for stubs that support fast tracepoints.  GDB

  reports support for this feature in the qSupported packet.

qTfSTM, qTsSTM

  List static tracepoint markers in the target program.

qTSTMat

  List static tracepoint markers at a given address in the target

  program.

qXfer:statictrace:read

  Read the static trace data collected (by a `collect $_sdata'

  tracepoint action).  The remote stub reports support for this packet

  to gdb's qSupported query.

QAllow

  Send the current settings of GDB's permission flags.

QTDPsrc

  Send part of the source (textual) form of a tracepoint definition,

  which includes location, conditional, and action list.

* The source command now accepts a -s option to force searching for the

  script in the source search path even if the script name specifies

  a directory.

* New features in the GDB remote stub, GDBserver

  - GDBserver now support tracepoints (including fast tracepoints, and

    static tracepoints).  The feature is currently supported by the

    i386-linux and amd64-linux builds.  See the "Tracepoints support

    in gdbserver" section in the manual for more information.

    GDBserver JIT compiles the tracepoint's conditional agent

    expression bytecode into native code whenever possible for low

    overhead dynamic tracepoints conditionals.  For such tracepoints,

    an expression that examines program state is evaluated when the

    tracepoint is reached, in order to determine whether to capture

    trace data.  If the condition is simple and false, processing the

    tracepoint finishes very quickly and no data is gathered.

    GDBserver interfaces with the UST (LTTng Userspace Tracer) library

    for static tracepoints support.

  - GDBserver now supports x86_64 Windows 64-bit debugging.

* GDB now sends xmlRegisters= in qSupported packet to indicate that

  it understands register description.

* The --batch flag now disables pagination and queries.

* X86 general purpose registers

  GDB now supports reading/writing byte, word and double-word x86

  general purpose registers directly.  This means you can use, say,

  $ah or $ax to refer, respectively, to the byte register AH and

  16-bit word register AX that are actually portions of the 32-bit

  register EAX or 64-bit register RAX.

* The `commands' command now accepts a range of breakpoints to modify.

  A plain `commands' following a command that creates multiple

  breakpoints affects all the breakpoints set by that command.  This

  applies to breakpoints set by `rbreak', and also applies when a

  single `break' command creates multiple breakpoints (e.g.,

  breakpoints on overloaded c++ functions).

* The `rbreak' command now accepts a filename specification as part of

  its argument, limiting the functions selected by the regex to those

  in the specified file.

* Support for remote debugging Windows and SymbianOS shared libraries

  from Unix hosts has been improved.  Non Windows GDB builds now can

  understand target reported file names that follow MS-DOS based file

  system semantics, such as file names that include drive letters and

  use the backslash character as directory separator.  This makes it

  possible to transparently use the "set sysroot" and "set

  solib-search-path" on Unix hosts to point as host copies of the

  target's shared libraries.  See the new command "set

  target-file-system-kind" described below, and the "Commands to

  specify files" section in the user manual for more information.

* New commands

eval template, expressions...

  Convert the values of one or more expressions under the control

  of the string template to a command line, and call it.

set target-file-system-kind unix|dos-based|auto

show target-file-system-kind

  Set or show the assumed file system kind for target reported file

  names.

save breakpoints 

  Save all current breakpoint definitions to a file suitable for use

  in a later debugging session.  To read the saved breakpoint

  definitions, use the `source' command.

`save tracepoints' is a new alias for `save-tracepoints'.  The latter

is now deprecated.

info static-tracepoint-markers

  Display information about static tracepoint markers in the target.

strace FN | FILE:LINE | *ADDR | -m MARKER_ID

  Define a static tracepoint by probing a marker at the given

  function, line, address, or marker ID.

set observer on|off

show observer

  Enable and disable observer mode.

set may-write-registers on|off

set may-write-memory on|off

set may-insert-breakpoints on|off

set may-insert-tracepoints on|off

set may-insert-fast-tracepoints on|off

set may-interrupt on|off

  Set individual permissions for GDB effects on the target.  Note that

  some of these settings can have undesirable or surprising

  consequences, particularly when changed in the middle of a session.

  For instance, disabling the writing of memory can prevent

  breakpoints from being inserted, cause single-stepping to fail, or

  even crash your program, if you disable after breakpoints have been

  inserted.  However, GDB should not crash.

set record memory-query on|off

show record memory-query

  Control whether to stop the inferior if memory changes caused

  by an instruction cannot be recorded.

* Changed commands

disassemble

  The disassemble command now supports "start,+length" form of two arguments.

* Python scripting

** GDB now provides a new directory location, called the python directory,

   where Python scripts written for GDB can be installed.  The location

   of that directory is /python, where 

   is the GDB data directory.  For more details, see section `Scripting

   GDB using Python' in the manual.

** The GDB Python API now has access to breakpoints, symbols, symbol

   tables, program spaces, inferiors, threads and frame's code blocks.

   Additionally, GDB Parameters can now be created from the API, and

   manipulated via set/show in the CLI.

** New functions gdb.target_charset, gdb.target_wide_charset,

   gdb.progspaces, gdb.current_progspace, and gdb.string_to_argv.

** New exception gdb.GdbError.

** Pretty-printers are now also looked up in the current program space.

** Pretty-printers can now be individually enabled and disabled.

** GDB now looks for names of Python scripts to auto-load in a

   special section named `.debug_gdb_scripts', in addition to looking

   for a OBJFILE-gdb.py script when OBJFILE is read by the debugger.

* Tracepoint actions were unified with breakpoint commands. In particular,

there are no longer differences in "info break" output for breakpoints and

tracepoints and the "commands" command can be used for both tracepoints and

regular breakpoints.

* New targets

ARM Symbian                     arm*-*-symbianelf*

* D language support.

  GDB now supports debugging programs written in the D programming

  language.

* GDB now supports the extended ptrace interface for PowerPC which is

  available since Linux kernel version 2.6.34.  This automatically enables

  any hardware breakpoints and additional hardware watchpoints available in

  the processor.  The old ptrace interface exposes just one hardware

  watchpoint and no hardware breakpoints.

* GDB is now able to use the Data Value Compare (DVC) register available on

  embedded PowerPC processors to implement in hardware simple watchpoint

  conditions of the form:

  watch ADDRESS|VARIABLE if ADDRESS|VARIABLE == CONSTANT EXPRESSION

  This works in native GDB running on Linux kernels with the extended ptrace

  interface mentioned above.

*** Changes in GDB 7.1

* C++ Improvements

  ** Namespace Support

  GDB now supports importing of namespaces in C++.  This enables the

  user to inspect variables from imported namespaces.  Support for

  namepace aliasing has also been added.  So, if a namespace is

  aliased in the current scope (e.g. namepace C=A; ) the user can

  print variables using the alias (e.g. (gdb) print C::x).

  ** Bug Fixes

  All known bugs relating to the printing of virtual base class were

  fixed.  It is now possible to call overloaded static methods using a

  qualified name.

  ** Cast Operators

  The C++ cast operators static_cast<>, dynamic_cast<>, const_cast<>,

  and reinterpret_cast<> are now handled by the C++ expression parser.

* New targets

Xilinx MicroBlaze               microblaze-*-*

Renesas RX                      rx-*-elf

* New Simulators

Xilinx MicroBlaze               microblaze

Renesas RX                      rx

* Multi-program debugging.

  GDB now has support for multi-program (a.k.a. multi-executable or

  multi-exec) debugging.  This allows for debugging multiple inferiors

  simultaneously each running a different program under the same GDB

  session.  See "Debugging Multiple Inferiors and Programs" in the

  manual for more information.  This implied some user visible changes

  in the multi-inferior support.  For example, "info inferiors" now

  lists inferiors that are not running yet or that have exited

  already.  See also "New commands" and "New options" below.

* New tracing features

  GDB's tracepoint facility now includes several new features:

  ** Trace state variables

  GDB tracepoints now include support for trace state variables, which

  are variables managed by the target agent during a tracing

  experiment.  They are useful for tracepoints that trigger each

  other, so for instance one tracepoint can count hits in a variable,

  and then a second tracepoint has a condition that is true when the

  count reaches a particular value.  Trace state variables share the

  $-syntax of GDB convenience variables, and can appear in both

  tracepoint actions and condition expressions.  Use the "tvariable"

  command to create, and "info tvariables" to view; see "Trace State

  Variables" in the manual for more detail.

  ** Fast tracepoints

  GDB now includes an option for defining fast tracepoints, which

  targets may implement more efficiently, such as by installing a jump

  into the target agent rather than a trap instruction.  The resulting

  speedup can be by two orders of magnitude or more, although the

  tradeoff is that some program locations on some target architectures

  might not allow fast tracepoint installation, for instance if the

  instruction to be replaced is shorter than the jump.  To request a

  fast tracepoint, use the "ftrace" command, with syntax identical to

  the regular trace command.

  ** Disconnected tracing

  It is now possible to detach GDB from the target while it is running

  a trace experiment, then reconnect later to see how the experiment

  is going.  In addition, a new variable disconnected-tracing lets you

  tell the target agent whether to continue running a trace if the

  connection is lost unexpectedly.

  ** Trace files

  GDB now has the ability to save the trace buffer into a file, and

  then use that file as a target, similarly to you can do with

  corefiles.  You can select trace frames, print data that was

  collected in them, and use tstatus to display the state of the

  tracing run at the moment that it was saved.  To create a trace

  file, use "tsave ", and to use it, do "target tfile

  ".

  ** Circular trace buffer

  You can ask the target agent to handle the trace buffer as a

  circular buffer, discarding the oldest trace frames to make room for

  newer ones, by setting circular-trace-buffer to on.  This feature may

  not be available for all target agents.

* Changed commands

disassemble

  The disassemble command, when invoked with two arguments, now requires

  the arguments to be comma-separated.

info variables

  The info variables command now displays variable definitions.  Files

  which only declare a variable are not shown.

source

  The source command is now capable of sourcing Python scripts.

  This feature is dependent on the debugger being build with Python

  support.

  Related to this enhancement is also the introduction of a new command

  "set script-extension" (see below).

* New commands (for set/show, see "New options" below)

record save []

  Save a file (in core file format) containing the process record

  execution log for replay debugging at a later time.

record restore 

  Restore the process record execution log that was saved at an

  earlier time, for replay debugging.

add-inferior [-copies ] [-exec ]

  Add a new inferior.

clone-inferior [-copies ] [ID]

  Make a new inferior ready to execute the same program another

  inferior has loaded.

remove-inferior ID

  Remove an inferior.

maint info program-spaces

  List the program spaces loaded into GDB.

set remote interrupt-sequence [Ctrl-C | BREAK | BREAK-g]

show remote interrupt-sequence

  Allow the user to select one of ^C, a BREAK signal or BREAK-g

  as the sequence to the remote target in order to interrupt the execution.

  Ctrl-C is a default.  Some system prefers BREAK which is high level of

  serial line for some certain time.  Linux kernel prefers BREAK-g, a.k.a

  Magic SysRq g.  It is BREAK signal and character 'g'.

set remote interrupt-on-connect [on | off]

show remote interrupt-on-connect

  When interrupt-on-connect is ON, gdb sends interrupt-sequence to

  remote target when gdb connects to it.  This is needed when you debug

  Linux kernel.

set remotebreak [on | off]

show remotebreak

Deprecated.  Use "set/show remote interrupt-sequence" instead.

tvariable $NAME [ = EXP ]

  Create or modify a trace state variable.

info tvariables

  List trace state variables and their values.

delete tvariable $NAME ...

  Delete one or more trace state variables.

teval EXPR, ...

  Evaluate the given expressions without collecting anything into the

  trace buffer. (Valid in tracepoint actions only.)

ftrace FN / FILE:LINE / *ADDR

  Define a fast tracepoint at the given function, line, or address.

* New expression syntax

  GDB now parses the 0b prefix of binary numbers the same way as GCC does.

  GDB now parses 0b101010 identically with 42.

* New options

set follow-exec-mode new|same

show follow-exec-mode

  Control whether GDB reuses the same inferior across an exec call or

  creates a new one.  This is useful to be able to restart the old

  executable after the inferior having done an exec call.

set default-collect EXPR, ...

show default-collect

   Define a list of expressions to be collected at each tracepoint.

   This is a useful way to ensure essential items are not overlooked,

   such as registers or a critical global variable.

set disconnected-tracing

show disconnected-tracing

   If set to 1, the target is instructed to continue tracing if it

   loses its connection to GDB.  If 0, the target is to stop tracing

   upon disconnection.

set circular-trace-buffer

show circular-trace-buffer

   If set to on, the target is instructed to use a circular trace buffer

   and discard the oldest trace frames instead of stopping the trace due

   to a full trace buffer.  If set to off, the trace stops when the buffer

   fills up.  Some targets may not support this.

set script-extension off|soft|strict

show script-extension

   If set to "off", the debugger does not perform any script language

   recognition, and all sourced files are assumed to be GDB scripts.

   If set to "soft" (the default), files are sourced according to

   filename extension, falling back to GDB scripts if the first

   evaluation failed.

   If set to "strict", files are sourced according to filename extension.

set ada trust-PAD-over-XVS on|off

show ada trust-PAD-over-XVS

   If off, activate a workaround against a bug in the debugging information

   generated by the compiler for PAD types (see gcc/exp_dbug.ads in

   the GCC sources for more information about the GNAT encoding and

   PAD types in particular).  It is always safe to set this option to

   off, but this introduces a slight performance penalty.  The default

   is on.

* Python API Improvements

  ** GDB provides the new class gdb.LazyString.  This is useful in

     some pretty-printing cases.  The new method gdb.Value.lazy_string

     provides a simple way to create objects of this type.

  ** The fields returned by gdb.Type.fields now have an

     `is_base_class' attribute.

  ** The new method gdb.Type.range returns the range of an array type.

  ** The new method gdb.parse_and_eval can be used to parse and

     evaluate an expression.

* New remote packets

QTDV

   Define a trace state variable.

qTV

   Get the current value of a trace state variable.

QTDisconnected

   Set desired tracing behavior upon disconnection.

QTBuffer:circular

   Set the trace buffer to be linear or circular.

qTfP, qTsP

   Get data about the tracepoints currently in use.

* Bug fixes

Process record now works correctly with hardware watchpoints.

Multiple bug fixes have been made to the mips-irix port, making it

much more reliable. In particular:

  - Debugging threaded applications is now possible again.  Previously,

    GDB would hang while starting the program, or while waiting for

    the program to stop at a breakpoint.

  - Attaching to a running process no longer hangs.

  - An error occurring while loading a core file has been fixed.

  - Changing the value of the PC register now works again.  This fixes

    problems observed when using the "jump" command, or when calling

    a function from GDB, or even when assigning a new value to $pc.

  - With the "finish" and "return" commands, the return value for functions

    returning a small array is now correctly printed.

  - It is now possible to break on shared library code which gets executed

    during a shared library init phase (code executed while executing

    their .init section).  Previously, the breakpoint would have no effect.

  - GDB is now able to backtrace through the signal handler for

    non-threaded programs.

PIE (Position Independent Executable) programs debugging is now supported.

This includes debugging execution of PIC (Position Independent Code) shared

libraries although for that, it should be possible to run such libraries as an

executable program.

*** Changes in GDB 7.0

* GDB now has an interface for JIT compilation.  Applications that

dynamically generate code can create symbol files in memory and register

them with GDB.  For users, the feature should work transparently, and

for JIT developers, the interface is documented in the GDB manual in the

"JIT Compilation Interface" chapter.

* Tracepoints may now be conditional.  The syntax is as for

breakpoints; either an "if" clause appended to the "trace" command,

or the "condition" command is available.  GDB sends the condition to

the target for evaluation using the same bytecode format as is used

for tracepoint actions.

* The disassemble command now supports: an optional /r modifier, print the

raw instructions in hex as well as in symbolic form, and an optional /m

modifier to print mixed source+assembly.

* Process record and replay

  In a architecture environment that supports ``process record and

  replay'', ``process record and replay'' target can record a log of

  the process execution, and replay it with both forward and reverse

  execute commands.

* Reverse debugging: GDB now has new commands reverse-continue, reverse-

step, reverse-next, reverse-finish, reverse-stepi, reverse-nexti, and

set execution-direction {forward|reverse}, for targets that support

reverse execution.

* GDB now supports hardware watchpoints on MIPS/Linux systems.  This

feature is available with a native GDB running on kernel version

2.6.28 or later.

* GDB now has support for multi-byte and wide character sets on the

target.  Strings whose character type is wchar_t, char16_t, or

char32_t are now correctly printed.  GDB supports wide- and unicode-

literals in C, that is, L'x', L"string", u'x', u"string", U'x', and

U"string" syntax.  And, GDB allows the "%ls" and "%lc" formats in

`printf'.  This feature requires iconv to work properly; if your

system does not have a working iconv, GDB can use GNU libiconv.  See

the installation instructions for more information.

* GDB now supports automatic retrieval of shared library files from

remote targets.  To use this feature, specify a system root that begins

with the `remote:' prefix, either via the `set sysroot' command or via

the `--with-sysroot' configure-time option.

* "info sharedlibrary" now takes an optional regex of libraries to show,

and it now reports if a shared library has no debugging information.

* Commands `set debug-file-directory', `set solib-search-path' and `set args'

now complete on file names.

* When completing in expressions, gdb will attempt to limit

completions to allowable structure or union fields, where appropriate.

For instance, consider:

    # struct example { int f1; double f2; };

    # struct example variable;

    (gdb) p variable.

If the user types TAB at the end of this command line, the available

completions will be "f1" and "f2".

* Inlined functions are now supported.  They show up in backtraces, and

the "step", "next", and "finish" commands handle them automatically.

* GDB now supports the token-splicing (##) and stringification (#)

operators when expanding macros.  It also supports variable-arity

macros.

* GDB now supports inspecting extra signal information, exported by

the new $_siginfo convenience variable.  The feature is currently

implemented on linux ARM, i386 and amd64.

* GDB can now display the VFP floating point registers and NEON vector

registers on ARM targets.  Both ARM GNU/Linux native GDB and gdbserver

can provide these registers (requires Linux 2.6.30 or later).  Remote

and simulator targets may also provide them.

* New remote packets

qSearch:memory:

  Search memory for a sequence of bytes.

QStartNoAckMode

  Turn off `+'/`-' protocol acknowledgments to permit more efficient

  operation over reliable transport links.  Use of this packet is

  controlled by the `set remote noack-packet' command.

vKill

  Kill the process with the specified process ID.  Use this in preference

  to `k' when multiprocess protocol extensions are supported.

qXfer:osdata:read

  Obtains additional operating system information

qXfer:siginfo:read

qXfer:siginfo:write

  Read or write additional signal information.

* Removed remote protocol undocumented extension

  An undocumented extension to the remote protocol's `S' stop reply

  packet that permited the stub to pass a process id was removed.

  Remote servers should use the `T' stop reply packet instead.

* GDB now supports multiple function calling conventions according to the

DWARF-2 DW_AT_calling_convention function attribute.

* The SH target utilizes the aforementioned change to distinguish between gcc

and Renesas calling convention.  It also adds the new CLI commands

`set/show sh calling-convention'.

* GDB can now read compressed debug sections, as produced by GNU gold

with the --compress-debug-sections=zlib flag.

* 64-bit core files are now supported on AIX.

* Thread switching is now supported on Tru64.

* Watchpoints can now be set on unreadable memory locations, e.g. addresses

which will be allocated using malloc later in program execution.

* The qXfer:libraries:read remote procotol packet now allows passing a

list of section offsets.

* On GNU/Linux, GDB can now attach to stopped processes.  Several race

conditions handling signals delivered during attach or thread creation

have also been fixed.

* GDB now supports the use of DWARF boolean types for Ada's type Boolean.

From the user's standpoint, all unqualified instances of True and False

are treated as the standard definitions, regardless of context.

* GDB now parses C++ symbol and type names more flexibly.  For

example, given:

   template class C { };

   C c;

GDB will now correctly handle all of:

   ptype C

   ptype C

   ptype C

   ptype C

* New features in the GDB remote stub, gdbserver

  - The "--wrapper" command-line argument tells gdbserver to use a

  wrapper program to launch programs for debugging.

  - On PowerPC and S/390 targets, it is now possible to use a single

  gdbserver executable to debug both 32-bit and 64-bit programs.

  (This requires gdbserver itself to be built as a 64-bit executable.)

  - gdbserver uses the new noack protocol mode for TCP connections to

  reduce communications latency, if also supported and enabled in GDB.

  - Support for the sparc64-linux-gnu target is now included in

  gdbserver.

  - The amd64-linux build of gdbserver now supports debugging both

    32-bit and 64-bit programs.

  - The i386-linux, amd64-linux, and i386-win32 builds of gdbserver

    now support hardware watchpoints, and will use them automatically

    as appropriate.

* Python scripting

  GDB now has support for scripting using Python.  Whether this is

  available is determined at configure time.

  New GDB commands can now be written in Python.

* Ada tasking support

  Ada tasks can now be inspected in GDB. The following commands have

  been introduced:

    info tasks

      Print the list of Ada tasks.

    info task N

      Print detailed information about task number N.

    task

      Print the task number of the current task.

    task N

      Switch the context of debugging to task number N.

* Support for user-defined prefixed commands.  The "define" command can

add new commands to existing prefixes, e.g. "target".

* Multi-inferior, multi-process debugging.

  GDB now has generalized support for multi-inferior debugging.  See

  "Debugging Multiple Inferiors" in the manual for more information.

  Although availability still depends on target support, the command

  set is more uniform now.  The GNU/Linux specific multi-forks support

  has been migrated to this new framework.  This implied some user

  visible changes; see "New commands" and also "Removed commands"

  below.

* Target descriptions can now describe the target OS ABI.  See the

"Target Description Format" section in the user manual for more

information.

* Target descriptions can now describe "compatible" architectures

to indicate that the target can execute applications for a different

architecture in addition to those for the main target architecture.

See the "Target Description Format" section in the user manual for

more information.

* Multi-architecture debugging.

  GDB now includes general supports for debugging applications on

  hybrid systems that use more than one single processor architecture

  at the same time.  Each such hybrid architecture still requires

  specific support to be added.  The only hybrid architecture supported

  in this version of GDB is the Cell Broadband Engine.

* GDB now supports integrated debugging of Cell/B.E. applications that

use both the PPU and SPU architectures.  To enable support for hybrid

Cell/B.E. debugging, you need to configure GDB to support both the

powerpc-linux or powerpc64-linux and the spu-elf targets, using the

--enable-targets configure option.

* Non-stop mode debugging.

  For some targets, GDB now supports an optional mode of operation in

  which you can examine stopped threads while other threads continue

  to execute freely.  This is referred to as non-stop mode, with the

  old mode referred to as all-stop mode.  See the "Non-Stop Mode"

  section in the user manual for more information.

  To be able to support remote non-stop debugging, a remote stub needs

  to implement the non-stop mode remote protocol extensions, as

  described in the "Remote Non-Stop" section of the user manual.  The

  GDB remote stub, gdbserver, has been adjusted to support these

  extensions on linux targets.

* New commands (for set/show, see "New options" below)

catch syscall [NAME(S) | NUMBER(S)]

  Catch system calls.  Arguments, which should be names of system

  calls or their numbers, mean catch only those syscalls.  Without

  arguments, every syscall will be caught.  When the inferior issues

  any of the specified syscalls, GDB will stop and announce the system

  call, both when it is called and when its call returns.  This

  feature is currently available with a native GDB running on the

  Linux Kernel, under the following architectures: x86, x86_64,

  PowerPC and PowerPC64.

find [/size-char] [/max-count] start-address, end-address|+search-space-size,

    val1 [, val2, ...]

  Search memory for a sequence of bytes.

maint set python print-stack

maint show python print-stack

  Show a stack trace when an error is encountered in a Python script.

python [CODE]

  Invoke CODE by passing it to the Python interpreter.

macro define

macro list

macro undef

  These allow macros to be defined, undefined, and listed

  interactively.

info os processes

  Show operating system information about processes.

info inferiors

  List the inferiors currently under GDB's control.

inferior NUM

  Switch focus to inferior number NUM.

detach inferior NUM

  Detach from inferior number NUM.

kill inferior NUM

  Kill inferior number NUM.

* New options

set spu stop-on-load

show spu stop-on-load

  Control whether to stop for new SPE threads during Cell/B.E. debugging.

set spu auto-flush-cache

show spu auto-flush-cache

  Control whether to automatically flush the software-managed cache

  during Cell/B.E. debugging.

set sh calling-convention

show sh calling-convention

  Control the calling convention used when calling SH target functions.

set debug timestamp

show debug timestamp

  Control display of timestamps with GDB debugging output.

set disassemble-next-line

show disassemble-next-line

  Control display of disassembled source lines or instructions when

  the debuggee stops.

set remote noack-packet

show remote noack-packet

  Set/show the use of remote protocol QStartNoAckMode packet.  See above

  under "New remote packets."

set remote query-attached-packet

show remote query-attached-packet

  Control use of remote protocol `qAttached' (query-attached) packet.

set remote read-siginfo-object

show remote read-siginfo-object

  Control use of remote protocol `qXfer:siginfo:read' (read-siginfo-object)

  packet.

set remote write-siginfo-object

show remote write-siginfo-object

  Control use of remote protocol `qXfer:siginfo:write' (write-siginfo-object)

  packet.

set remote reverse-continue

show remote reverse-continue

  Control use of remote protocol 'bc' (reverse-continue) packet.

set remote reverse-step

show remote reverse-step

  Control use of remote protocol 'bs' (reverse-step) packet.

set displaced-stepping

show displaced-stepping

  Control displaced stepping mode.  Displaced stepping is a way to

  single-step over breakpoints without removing them from the debuggee.

  Also known as "out-of-line single-stepping".

set debug displaced

show debug displaced

  Control display of debugging info for displaced stepping.

maint set internal-error

maint show internal-error

  Control what GDB does when an internal error is detected.