gdb/doc/gdb.info-7

This is Info file ./gdb.info, produced by Makeinfo version 1.68 from
the input file gdb.texinfo.

START-INFO-DIR-ENTRY
* Gdb: (gdb).                     The GNU debugger.
END-INFO-DIR-ENTRY
   This file documents the GNU debugger GDB.

   This is the Seventh Edition, February 1999, of `Debugging with GDB:
the GNU Source-Level Debugger' for GDB Version 4.18.

   Copyright (C) 1988-1999 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the entire resulting derived work is distributed under the terms
of a permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions.


File: gdb.info,  Node: Nindy Options,  Next: Nindy Reset,  Prev: Nindy Startup,  Up: i960-Nindy Remote

Options for Nindy
.................

   These are the startup options for beginning your GDB session with a
Nindy-960 board attached:

`-r PORT'
     Specify the serial port name of a serial interface to be used to
     connect to the target system.  This option is only available when
     GDB is configured for the Intel 960 target architecture.  You may
     specify PORT as any of: a full pathname (e.g. `-r /dev/ttya'), a
     device name in `/dev' (e.g. `-r ttya'), or simply the unique
     suffix for a specific `tty' (e.g. `-r a').

`-O'
     (An uppercase letter "O", not a zero.)  Specify that GDB should use
     the "old" Nindy monitor protocol to connect to the target system.
     This option is only available when GDB is configured for the Intel
     960 target architecture.

          *Warning:* if you specify `-O', but are actually trying to
          connect to a target system that expects the newer protocol,
          the connection fails, appearing to be a speed mismatch.  GDB
          repeatedly attempts to reconnect at several different line
          speeds.  You can abort this process with an interrupt.

`-brk'
     Specify that GDB should first send a `BREAK' signal to the target
     system, in an attempt to reset it, before connecting to a Nindy
     target.

          *Warning:* Many target systems do not have the hardware that
          this requires; it only works with a few boards.

   The standard `-b' option controls the line speed used on the serial
port.


File: gdb.info,  Node: Nindy Reset,  Prev: Nindy Options,  Up: i960-Nindy Remote

Nindy reset command
...................

`reset'
     For a Nindy target, this command sends a "break" to the remote
     target system; this is only useful if the target has been equipped
     with a circuit to perform a hard reset (or some other interesting
     action) when a break is detected.


File: gdb.info,  Node: UDI29K Remote,  Next: EB29K Remote,  Prev: i960-Nindy Remote,  Up: Remote

The UDI protocol for AMD29K
---------------------------

   GDB supports AMD's UDI ("Universal Debugger Interface") protocol for
debugging the a29k processor family.  To use this configuration with
AMD targets running the MiniMON monitor, you need the program `MONTIP',
available from AMD at no charge.  You can also use GDB with the
UDI-conformant a29k simulator program `ISSTIP', also available from AMD.

`target udi KEYWORD'
     Select the UDI interface to a remote a29k board or simulator, where
     KEYWORD is an entry in the AMD configuration file `udi_soc'.  This
     file contains keyword entries which specify parameters used to
     connect to a29k targets.  If the `udi_soc' file is not in your
     working directory, you must set the environment variable `UDICONF'
     to its pathname.


File: gdb.info,  Node: EB29K Remote,  Next: VxWorks Remote,  Prev: UDI29K Remote,  Up: Remote

The EBMON protocol for AMD29K
-----------------------------

   AMD distributes a 29K development board meant to fit in a PC,
together with a DOS-hosted monitor program called `EBMON'.  As a
shorthand term, this development system is called the "EB29K".  To use
GDB from a Unix system to run programs on the EB29K board, you must
first connect a serial cable between the PC (which hosts the EB29K
board) and a serial port on the Unix system.  In the following, we
assume you've hooked the cable between the PC's `COM1' port and
`/dev/ttya' on the Unix system.

* Menu:

* Comms (EB29K)::               Communications setup
* gdb-EB29K::                   EB29K cross-debugging
* Remote Log::                  Remote log


File: gdb.info,  Node: Comms (EB29K),  Next: gdb-EB29K,  Up: EB29K Remote

Communications setup
....................

   The next step is to set up the PC's port, by doing something like
this in DOS on the PC:

     C:\> MODE com1:9600,n,8,1,none

This example--run on an MS DOS 4.0 system--sets the PC port to 9600
bps, no parity, eight data bits, one stop bit, and no "retry" action;
you must match the communications parameters when establishing the Unix
end of the connection as well.

   To give control of the PC to the Unix side of the serial line, type
the following at the DOS console:

     C:\> CTTY com1

(Later, if you wish to return control to the DOS console, you can use
the command `CTTY con'--but you must send it over the device that had
control, in our example over the `COM1' serial line).

   From the Unix host, use a communications program such as `tip' or
`cu' to communicate with the PC; for example,

     cu -s 9600 -l /dev/ttya

The `cu' options shown specify, respectively, the linespeed and the
serial port to use.  If you use `tip' instead, your command line may
look something like the following:

     tip -9600 /dev/ttya

Your system may require a different name where we show `/dev/ttya' as
the argument to `tip'.  The communications parameters, including which
port to use, are associated with the `tip' argument in the "remote"
descriptions file--normally the system table `/etc/remote'.

   Using the `tip' or `cu' connection, change the DOS working directory
to the directory containing a copy of your 29K program, then start the
PC program `EBMON' (an EB29K control program supplied with your board
by AMD).  You should see an initial display from `EBMON' similar to the
one that follows, ending with the `EBMON' prompt `#'--

     C:\> G:
     
     G:\> CD \usr\joe\work29k
     
     G:\USR\JOE\WORK29K> EBMON
     Am29000 PC Coprocessor Board Monitor, version 3.0-18
     Copyright 1990 Advanced Micro Devices, Inc.
     Written by Gibbons and Associates, Inc.
     
     Enter '?' or 'H' for help
     
     PC Coprocessor Type   = EB29K
     I/O Base              = 0x208
     Memory Base           = 0xd0000
     
     Data Memory Size      = 2048KB
     Available I-RAM Range = 0x8000 to 0x1fffff
     Available D-RAM Range = 0x80002000 to 0x801fffff
     
     PageSize              = 0x400
     Register Stack Size   = 0x800
     Memory Stack Size     = 0x1800
     
     CPU PRL               = 0x3
     Am29027 Available     = No
     Byte Write Available  = Yes
     
     # ~.

   Then exit the `cu' or `tip' program (done in the example by typing
`~.' at the `EBMON' prompt).  `EBMON' keeps running, ready for GDB to
take over.

   For this example, we've assumed what is probably the most convenient
way to make sure the same 29K program is on both the PC and the Unix
system: a PC/NFS connection that establishes "drive `G:'" on the PC as
a file system on the Unix host.  If you do not have PC/NFS or something
similar connecting the two systems, you must arrange some other
way--perhaps floppy-disk transfer--of getting the 29K program from the
Unix system to the PC; GDB does *not* download it over the serial line.


File: gdb.info,  Node: gdb-EB29K,  Next: Remote Log,  Prev: Comms (EB29K),  Up: EB29K Remote

EB29K cross-debugging
.....................

   Finally, `cd' to the directory containing an image of your 29K
program on the Unix system, and start GDB--specifying as argument the
name of your 29K program:

     cd /usr/joe/work29k
     gdb myfoo

   Now you can use the `target' command:

     target amd-eb /dev/ttya 9600 MYFOO

In this example, we've assumed your program is in a file called
`myfoo'.  Note that the filename given as the last argument to `target
amd-eb' should be the name of the program as it appears to DOS.  In our
example this is simply `MYFOO', but in general it can include a DOS
path, and depending on your transfer mechanism may not resemble the
name on the Unix side.

   At this point, you can set any breakpoints you wish; when you are
ready to see your program run on the 29K board, use the GDB command
`run'.

   To stop debugging the remote program, use the GDB `detach' command.

   To return control of the PC to its console, use `tip' or `cu' once
again, after your GDB session has concluded, to attach to `EBMON'.  You
can then type the command `q' to shut down `EBMON', returning control
to the DOS command-line interpreter.  Type `CTTY con' to return command
input to the main DOS console, and type `~.' to leave `tip' or `cu'.


File: gdb.info,  Node: Remote Log,  Prev: gdb-EB29K,  Up: EB29K Remote

Remote log
..........

   The `target amd-eb' command creates a file `eb.log' in the current
working directory, to help debug problems with the connection.
`eb.log' records all the output from `EBMON', including echoes of the
commands sent to it.  Running `tail -f' on this file in another window
often helps to understand trouble with `EBMON', or unexpected events on
the PC side of the connection.


File: gdb.info,  Node: ST2000 Remote,  Next: Hitachi Remote,  Prev: VxWorks Remote,  Up: Remote

GDB with a Tandem ST2000
------------------------

   To connect your ST2000 to the host system, see the manufacturer's
manual.  Once the ST2000 is physically attached, you can run:

     target st2000 DEV SPEED

to establish it as your debugging environment.  DEV is normally the
name of a serial device, such as `/dev/ttya', connected to the ST2000
via a serial line.  You can instead specify DEV as a TCP connection
(for example, to a serial line attached via a terminal concentrator)
using the syntax `HOSTNAME:PORTNUMBER'.

   The `load' and `attach' commands are *not* defined for this target;
you must load your program into the ST2000 as you normally would for
standalone operation.  GDB reads debugging information (such as
symbols) from a separate, debugging version of the program available on
your host computer.

   These auxiliary GDB commands are available to help you with the
ST2000 environment:

`st2000 COMMAND'
     Send a COMMAND to the STDBUG monitor.  See the manufacturer's
     manual for available commands.

`connect'
     Connect the controlling terminal to the STDBUG command monitor.
     When you are done interacting with STDBUG, typing either of two
     character sequences gets you back to the GDB command prompt:
     `<RET>~.' (Return, followed by tilde and period) or `<RET>~<C-d>'
     (Return, followed by tilde and control-D).


File: gdb.info,  Node: VxWorks Remote,  Next: ST2000 Remote,  Prev: EB29K Remote,  Up: Remote

GDB and VxWorks
---------------

   GDB enables developers to spawn and debug tasks running on networked
VxWorks targets from a Unix host.  Already-running tasks spawned from
the VxWorks shell can also be debugged.  GDB uses code that runs on
both the Unix host and on the VxWorks target.  The program `gdb' is
installed and executed on the Unix host.  (It may be installed with the
name `vxgdb', to distinguish it from a GDB for debugging programs on
the host itself.)

`VxWorks-timeout ARGS'
     All VxWorks-based targets now support the option `vxworks-timeout'.
     This option is set by the user, and  ARGS represents the number of
     seconds GDB waits for responses to rpc's.  You might use this if
     your VxWorks target is a slow software simulator or is on the far
     side of a thin network line.

   The following information on connecting to VxWorks was current when
this manual was produced; newer releases of VxWorks may use revised
procedures.

   To use GDB with VxWorks, you must rebuild your VxWorks kernel to
include the remote debugging interface routines in the VxWorks library
`rdb.a'.  To do this, define `INCLUDE_RDB' in the VxWorks configuration
file `configAll.h' and rebuild your VxWorks kernel.  The resulting
kernel contains `rdb.a', and spawns the source debugging task
`tRdbTask' when VxWorks is booted.  For more information on configuring
and remaking VxWorks, see the manufacturer's manual.

   Once you have included `rdb.a' in your VxWorks system image and set
your Unix execution search path to find GDB, you are ready to run GDB.
From your Unix host, run `gdb' (or `vxgdb', depending on your
installation).

   GDB comes up showing the prompt:

     (vxgdb)

* Menu:

* VxWorks Connection::          Connecting to VxWorks
* VxWorks Download::            VxWorks download
* VxWorks Attach::              Running tasks


File: gdb.info,  Node: VxWorks Connection,  Next: VxWorks Download,  Up: VxWorks Remote

Connecting to VxWorks
.....................

   The GDB command `target' lets you connect to a VxWorks target on the
network.  To connect to a target whose host name is "`tt'", type:

     (vxgdb) target vxworks tt

   GDB displays messages like these:

     Attaching remote machine across net...
     Connected to tt.

   GDB then attempts to read the symbol tables of any object modules
loaded into the VxWorks target since it was last booted.  GDB locates
these files by searching the directories listed in the command search
path (*note Your program's environment: Environment.); if it fails to
find an object file, it displays a message such as:

     prog.o: No such file or directory.

   When this happens, add the appropriate directory to the search path
with the GDB command `path', and execute the `target' command again.


File: gdb.info,  Node: VxWorks Download,  Next: VxWorks Attach,  Prev: VxWorks Connection,  Up: VxWorks Remote

VxWorks download
................

   If you have connected to the VxWorks target and you want to debug an
object that has not yet been loaded, you can use the GDB `load' command
to download a file from Unix to VxWorks incrementally.  The object file
given as an argument to the `load' command is actually opened twice:
first by the VxWorks target in order to download the code, then by GDB
in order to read the symbol table.  This can lead to problems if the
current working directories on the two systems differ.  If both systems
have NFS mounted the same filesystems, you can avoid these problems by
using absolute paths.  Otherwise, it is simplest to set the working
directory on both systems to the directory in which the object file
resides, and then to reference the file by its name, without any path.
For instance, a program `prog.o' may reside in `VXPATH/vw/demo/rdb' in
VxWorks and in `HOSTPATH/vw/demo/rdb' on the host.  To load this
program, type this on VxWorks:

     -> cd "VXPATH/vw/demo/rdb"
   v Then, in GDB, type:

     (vxgdb) cd HOSTPATH/vw/demo/rdb
     (vxgdb) load prog.o

   GDB displays a response similar to this:

     Reading symbol data from wherever/vw/demo/rdb/prog.o... done.

   You can also use the `load' command to reload an object module after
editing and recompiling the corresponding source file.  Note that this
makes GDB delete all currently-defined breakpoints, auto-displays, and
convenience variables, and to clear the value history.  (This is
necessary in order to preserve the integrity of debugger data
structures that reference the target system's symbol table.)


File: gdb.info,  Node: VxWorks Attach,  Prev: VxWorks Download,  Up: VxWorks Remote

Running tasks
.............

   You can also attach to an existing task using the `attach' command as
follows:

     (vxgdb) attach TASK

where TASK is the VxWorks hexadecimal task ID.  The task can be running
or suspended when you attach to it.  Running tasks are suspended at the
time of attachment.


File: gdb.info,  Node: Sparclet Remote,  Next: Simulator,  Prev: MIPS Remote,  Up: Remote

GDB and Sparclet
----------------

   GDB enables developers to debug tasks running on Sparclet targets
from a Unix host.  GDB uses code that runs on both the Unix host and on
the Sparclet target.  The program `gdb' is installed and executed on
the Unix host.

`timeout ARGS'
     GDB now supports the option `remotetimeout'.  This option is set
     by the user, and  ARGS represents the number of seconds GDB waits
     for responses.

   When compiling for debugging, include the options "-g" to get debug
information and "-Ttext" to relocate the program to where you wish to
load it on the target.  You may also want to add the options "-n" or
"-N" in order to reduce the size of the sections.

     sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N

   You can use objdump to verify that the addresses are what you
intended.

     sparclet-aout-objdump --headers --syms prog

   Once you have set your Unix execution search path to find GDB, you
are ready to run GDB.  From your Unix host, run `gdb' (or
`sparclet-aout-gdb', depending on your installation).

   GDB comes up showing the prompt:

     (gdbslet)

* Menu:

* Sparclet File::                Setting the file to debug
* Sparclet Connection::          Connecting to Sparclet
* Sparclet Download::            Sparclet download
* Sparclet Execution::           Running and debugging


File: gdb.info,  Node: Sparclet File,  Next: Sparclet Connection,  Up: Sparclet Remote

Setting file to debug
.....................

   The GDB command `file' lets you choose with program to debug.

     (gdbslet) file prog

   GDB then attempts to read the symbol table of `prog'.  GDB locates
the file by searching the directories listed in the command search path.
If the file was compiled with debug information (option "-g"), source
files will be searched as well.  GDB locates the source files by
searching the directories listed in the directory search path (*note
Your program's environment: Environment.).  If it fails to find a file,
it displays a message such as:

     prog: No such file or directory.

   When this happens, add the appropriate directories to the search
paths with the GDB commands `path' and `dir', and execute the `target'
command again.


File: gdb.info,  Node: Sparclet Connection,  Next: Sparclet Download,  Prev: Sparclet File,  Up: Sparclet Remote

Connecting to Sparclet
......................

   The GDB command `target' lets you connect to a Sparclet target.  To
connect to a target on serial port "`ttya'", type:

     (gdbslet) target sparclet /dev/ttya
     Remote target sparclet connected to /dev/ttya
     main () at ../prog.c:3

   GDB displays messages like these:

     Connected to ttya.


File: gdb.info,  Node: Sparclet Download,  Next: Sparclet Execution,  Prev: Sparclet Connection,  Up: Sparclet Remote

Sparclet download
.................

   Once connected to the Sparclet target, you can use the GDB `load'
command to download the file from the host to the target.  The file
name and load offset should be given as arguments to the `load' command.
Since the file format is aout, the program must be loaded to the
starting address.  You can use objdump to find out what this value is.
The load offset is an offset which is added to the VMA (virtual memory
address) of each of the file's sections.  For instance, if the program
`prog' was linked to text address 0x1201000, with data at 0x12010160
and bss at 0x12010170, in GDB, type:

     (gdbslet) load prog 0x12010000
     Loading section .text, size 0xdb0 vma 0x12010000

   If the code is loaded at a different address then what the program
was linked to, you may need to use the `section' and `add-symbol-file'
commands to tell GDB where to map the symbol table.


File: gdb.info,  Node: Sparclet Execution,  Prev: Sparclet Download,  Up: Sparclet Remote

Running and debugging
.....................

   You can now begin debugging the task using GDB's execution control
commands, `b', `step', `run', etc.  See the GDB manual for the list of
commands.

     (gdbslet) b main
     Breakpoint 1 at 0x12010000: file prog.c, line 3.
     (gdbslet) run
     Starting program: prog
     Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3
     3        char *symarg = 0;
     (gdbslet) step
     4        char *execarg = "hello!";
     (gdbslet)


File: gdb.info,  Node: Hitachi Remote,  Next: MIPS Remote,  Prev: ST2000 Remote,  Up: Remote

GDB and Hitachi microprocessors
-------------------------------

   GDB needs to know these things to talk to your Hitachi SH, H8/300,
or H8/500:

  1. that you want to use `target hms', the remote debugging interface
     for Hitachi microprocessors, or `target e7000', the in-circuit
     emulator for the Hitachi SH and the Hitachi 300H.  (`target hms' is
     the default when GDB is configured specifically for the Hitachi SH,
     H8/300, or H8/500.)

  2. what serial device connects your host to your Hitachi board (the
     first serial device available on your host is the default).

  3. what speed to use over the serial device.

* Menu:

* Hitachi Boards::      Connecting to Hitachi boards.
* Hitachi ICE::         Using the E7000 In-Circuit Emulator.
* Hitachi Special::     Special GDB commands for Hitachi micros.


File: gdb.info,  Node: Hitachi Boards,  Next: Hitachi ICE,  Up: Hitachi Remote

Connecting to Hitachi boards
............................

   Use the special `gdb' command `device PORT' if you need to
explicitly set the serial device.  The default PORT is the first
available port on your host.  This is only necessary on Unix hosts,
where it is typically something like `/dev/ttya'.

   `gdb' has another special command to set the communications speed:
`speed BPS'.  This command also is only used from Unix hosts; on DOS
hosts, set the line speed as usual from outside GDB with the DOS `mode'
command (for instance, `mode com2:9600,n,8,1,p' for a 9600 bps
connection).

   The `device' and `speed' commands are available only when you use a
Unix host to debug your Hitachi microprocessor programs.  If you use a
DOS host, GDB depends on an auxiliary terminate-and-stay-resident
program called `asynctsr' to communicate with the development board
through a PC serial port.  You must also use the DOS `mode' command to
set up the serial port on the DOS side.


File: gdb.info,  Node: Hitachi ICE,  Next: Hitachi Special,  Prev: Hitachi Boards,  Up: Hitachi Remote

Using the E7000 in-circuit emulator
...................................

   You can use the E7000 in-circuit emulator to develop code for either
the Hitachi SH or the H8/300H.  Use one of these forms of the `target
e7000' command to connect GDB to your E7000:

`target e7000 PORT SPEED'
     Use this form if your E7000 is connected to a serial port.  The
     PORT argument identifies what serial port to use (for example,
     `com2').  The third argument is the line speed in bits per second
     (for example, `9600').

`target e7000 HOSTNAME'
     If your E7000 is installed as a host on a TCP/IP network, you can
     just specify its hostname; GDB uses `telnet' to connect.


File: gdb.info,  Node: Hitachi Special,  Prev: Hitachi ICE,  Up: Hitachi Remote

Special GDB commands for Hitachi micros
.......................................

   Some GDB commands are available only on the H8/300 or the H8/500
configurations:

`set machine h8300'
`set machine h8300h'
     Condition GDB for one of the two variants of the H8/300
     architecture with `set machine'.  You can use `show machine' to
     check which variant is currently in effect.

`set memory MOD'
`show memory'
     Specify which H8/500 memory model (MOD) you are using with `set
     memory'; check which memory model is in effect with `show memory'.
     The accepted values for MOD are `small', `big', `medium', and
     `compact'.


File: gdb.info,  Node: MIPS Remote,  Next: Sparclet Remote,  Prev: Hitachi Remote,  Up: Remote

GDB and remote MIPS boards
--------------------------

   GDB can use the MIPS remote debugging protocol to talk to a MIPS
board attached to a serial line.  This is available when you configure
GDB with `--target=mips-idt-ecoff'.

   Use these GDB commands to specify the connection to your target
board:

`target mips PORT'
     To run a program on the board, start up `gdb' with the name of
     your program as the argument.  To connect to the board, use the
     command `target mips PORT', where PORT is the name of the serial
     port connected to the board.  If the program has not already been
     downloaded to the board, you may use the `load' command to
     download it.  You can then use all the usual GDB commands.

     For example, this sequence connects to the target board through a
     serial port, and loads and runs a program called PROG through the
     debugger:

          host$ gdb PROG
          GDB is free software and ...
          (gdb) target mips /dev/ttyb
          (gdb) load PROG
          (gdb) run

`target mips HOSTNAME:PORTNUMBER'
     On some GDB host configurations, you can specify a TCP connection
     (for instance, to a serial line managed by a terminal
     concentrator) instead of a serial port, using the syntax
     `HOSTNAME:PORTNUMBER'.

`target pmon PORT'

`target ddb PORT'

`target lsi PORT'
GDB also supports these special commands for MIPS targets:

`set processor ARGS'
`show processor'
     Use the `set processor' command to set the type of MIPS processor
     when you want to access processor-type-specific registers.  For
     example, `set processor R3041' tells GDB to use the CPO registers
     appropriate for the 3041 chip.  Use the `show processor' command
     to see what MIPS processor GDB is using.  Use the `info reg'
     command to see what registers GDB is using.

`set mipsfpu double'
`set mipsfpu single'
`set mipsfpu none'
`show mipsfpu'
     If your target board does not support the MIPS floating point
     coprocessor, you should use the command `set mipsfpu none' (if you
     need this, you may wish to put the command in your {No Value For
     "GDBINIT"} file).  This tells GDB how to find the return value of
     functions which return floating point values.  It also allows GDB
     to avoid saving the floating point registers when calling
     functions on the board.  If you are using a floating point
     coprocessor with only single precision floating point support, as
     on the R4650 processor, use the command `set mipsfpu single'.  The
     default double precision floating point coprocessor may be
     selected using `set mipsfpu double'.

     In previous versions the only choices were double precision or no
     floating point, so `set mipsfpu on' will select double precision
     and `set mipsfpu off' will select no floating point.

     As usual, you can inquire about the `mipsfpu' variable with `show
     mipsfpu'.

`set remotedebug N'
`show remotedebug'
     You can see some debugging information about communications with
     the board by setting the `remotedebug' variable.  If you set it to
     `1' using `set remotedebug 1', every packet is displayed.  If you
     set it to `2', every character is displayed.  You can check the
     current value at any time with the command `show remotedebug'.

`set timeout SECONDS'
`set retransmit-timeout SECONDS'
`show timeout'
`show retransmit-timeout'
     You can control the timeout used while waiting for a packet, in
     the MIPS remote protocol, with the `set timeout SECONDS' command.
     The default is 5 seconds.  Similarly, you can control the timeout
     used while waiting for an acknowledgement of a packet with the `set
     retransmit-timeout SECONDS' command.  The default is 3 seconds.
     You can inspect both values with `show timeout' and `show
     retransmit-timeout'.  (These commands are *only* available when
     GDB is configured for `--target=mips-idt-ecoff'.)

     The timeout set by `set timeout' does not apply when GDB is
     waiting for your program to stop.  In that case, GDB waits forever
     because it has no way of knowing how long the program is going to
     run before stopping.


File: gdb.info,  Node: Simulator,  Prev: Sparclet Remote,  Up: Remote

Simulated CPU target
--------------------

   For some configurations, GDB includes a CPU simulator that you can
use instead of a hardware CPU to debug your programs.  Currently,
simulators are available for ARM, D10V, D30V, FR30, H8/300, H8/500,
i960, M32R, MIPS, MN10200, MN10300, PowerPC, SH, Sparc, V850, W65, and
Z8000.

   For the Z8000 family, `target sim' simulates either the Z8002 (the
unsegmented variant of the Z8000 architecture) or the Z8001 (the
segmented variant).  The simulator recognizes which architecture is
appropriate by inspecting the object code.

`target sim ARGS'
     Debug programs on a simulated CPU.  If the simulator supports setup
     options, specify them via ARGS.

After specifying this target, you can debug programs for the simulated
CPU in the same style as programs for your host computer; use the
`file' command to load a new program image, the `run' command to run
your program, and so on.

   As well as making available all the usual machine registers (see
`info reg'), the Z8000 simulator provides three additional items of
information as specially named registers:

`cycles'
     Counts clock-ticks in the simulator.

`insts'
     Counts instructions run in the simulator.

`time'
     Execution time in 60ths of a second.

   You can refer to these values in GDB expressions with the usual
conventions; for example, `b fputc if $cycles>5000' sets a conditional
breakpoint that suspends only after at least 5000 simulated clock ticks.


File: gdb.info,  Node: Controlling GDB,  Next: Sequences,  Prev: Targets,  Up: Top

Controlling GDB
***************

   You can alter the way GDB interacts with you by using the `set'
command.  For commands controlling how GDB displays data, *note Print
settings: Print Settings.; other settings are described here.

* Menu:

* Prompt::                      Prompt
* Editing::                     Command editing
* History::                     Command history
* Screen Size::                 Screen size
* Numbers::                     Numbers
* Messages/Warnings::           Optional warnings and messages


File: gdb.info,  Node: Prompt,  Next: Editing,  Prev: Controlling GDB,  Up: Controlling GDB

Prompt
======

   GDB indicates its readiness to read a command by printing a string
called the "prompt".  This string is normally `(gdb)'.  You can change
the prompt string with the `set prompt' command.  For instance, when
debugging GDB with GDB, it is useful to change the prompt in one of the
GDB sessions so that you can always tell which one you are talking to.

   *Note:*  `set prompt' no longer adds a space for you after the
prompt you set.  This allows you to set a prompt which ends in a space
or a prompt that does not.

`set prompt NEWPROMPT'
     Directs GDB to use NEWPROMPT as its prompt string henceforth.

`show prompt'
     Prints a line of the form: `Gdb's prompt is: YOUR-PROMPT'


File: gdb.info,  Node: Editing,  Next: History,  Prev: Prompt,  Up: Controlling GDB

Command editing
===============

   GDB reads its input commands via the "readline" interface.  This GNU
library provides consistent behavior for programs which provide a
command line interface to the user.  Advantages are GNU Emacs-style or
"vi"-style inline editing of commands, `csh'-like history substitution,
and a storage and recall of command history across debugging sessions.

   You may control the behavior of command line editing in GDB with the
command `set'.

`set editing'
`set editing on'
     Enable command line editing (enabled by default).

`set editing off'
     Disable command line editing.

`show editing'
     Show whether command line editing is enabled.


File: gdb.info,  Node: History,  Next: Screen Size,  Prev: Editing,  Up: Controlling GDB

Command history
===============

   GDB can keep track of the commands you type during your debugging
sessions, so that you can be certain of precisely what happened.  Use
these commands to manage the GDB command history facility.

`set history filename FNAME'
     Set the name of the GDB command history file to FNAME.  This is
     the file where GDB reads an initial command history list, and
     where it writes the command history from this session when it
     exits.  You can access this list through history expansion or
     through the history command editing characters listed below.  This
     file defaults to the value of the environment variable
     `GDBHISTFILE', or to `./.gdb_history' if this variable is not set.

`set history save'
`set history save on'
     Record command history in a file, whose name may be specified with
     the `set history filename' command.  By default, this option is
     disabled.

`set history save off'
     Stop recording command history in a file.

`set history size SIZE'
     Set the number of commands which GDB keeps in its history list.
     This defaults to the value of the environment variable `HISTSIZE',
     or to 256 if this variable is not set.

   History expansion assigns special meaning to the character `!'.

   Since `!' is also the logical not operator in C, history expansion
is off by default. If you decide to enable history expansion with the
`set history expansion on' command, you may sometimes need to follow
`!' (when it is used as logical not, in an expression) with a space or
a tab to prevent it from being expanded.  The readline history
facilities do not attempt substitution on the strings `!=' and `!(',
even when history expansion is enabled.

   The commands to control history expansion are:

`set history expansion on'
`set history expansion'
     Enable history expansion.  History expansion is off by default.

`set history expansion off'
     Disable history expansion.

     The readline code comes with more complete documentation of
     editing and history expansion features.  Users unfamiliar with GNU
     Emacs or `vi' may wish to read it.

`show history'
`show history filename'
`show history save'
`show history size'
`show history expansion'
     These commands display the state of the GDB history parameters.
     `show history' by itself displays all four states.

`show commands'
     Display the last ten commands in the command history.

`show commands N'
     Print ten commands centered on command number N.

`show commands +'
     Print ten commands just after the commands last printed.


File: gdb.info,  Node: Screen Size,  Next: Numbers,  Prev: History,  Up: Controlling GDB

Screen size
===========

   Certain commands to GDB may produce large amounts of information
output to the screen.  To help you read all of it, GDB pauses and asks
you for input at the end of each page of output.  Type <RET> when you
want to continue the output, or `q' to discard the remaining output.
Also, the screen width setting determines when to wrap lines of output.
Depending on what is being printed, GDB tries to break the line at a
readable place, rather than simply letting it overflow onto the
following line.

   Normally GDB knows the size of the screen from the termcap data base
together with the value of the `TERM' environment variable and the
`stty rows' and `stty cols' settings. If this is not correct, you can
override it with the `set height' and `set width' commands:

`set height LPP'
`show height'
`set width CPL'
`show width'
     These `set' commands specify a screen height of LPP lines and a
     screen width of CPL characters.  The associated `show' commands
     display the current settings.

     If you specify a height of zero lines, GDB does not pause during
     output no matter how long the output is.  This is useful if output
     is to a file or to an editor buffer.

     Likewise, you can specify `set width 0' to prevent GDB from
     wrapping its output.


File: gdb.info,  Node: Numbers,  Next: Messages/Warnings,  Prev: Screen Size,  Up: Controlling GDB

Numbers
=======

   You can always enter numbers in octal, decimal, or hexadecimal in
GDB by the usual conventions: octal numbers begin with `0', decimal
numbers end with `.', and hexadecimal numbers begin with `0x'.  Numbers
that begin with none of these are, by default, entered in base 10;
likewise, the default display for numbers--when no particular format is
specified--is base 10.  You can change the default base for both input
and output with the `set radix' command.

`set input-radix BASE'
     Set the default base for numeric input.  Supported choices for
     BASE are decimal 8, 10, or 16.  BASE must itself be specified
     either unambiguously or using the current default radix; for
     example, any of

          set radix 012
          set radix 10.
          set radix 0xa

     sets the base to decimal.  On the other hand, `set radix 10'
     leaves the radix unchanged no matter what it was.

`set output-radix BASE'
     Set the default base for numeric display.  Supported choices for
     BASE are decimal 8, 10, or 16.  BASE must itself be specified
     either unambiguously or using the current default radix.

`show input-radix'
     Display the current default base for numeric input.

`show output-radix'
     Display the current default base for numeric display.


File: gdb.info,  Node: Messages/Warnings,  Prev: Numbers,  Up: Controlling GDB

Optional warnings and messages
==============================

   By default, GDB is silent about its inner workings.  If you are
running on a slow machine, you may want to use the `set verbose'
command.  This makes GDB tell you when it does a lengthy internal
operation, so you will not think it has crashed.

   Currently, the messages controlled by `set verbose' are those which
announce that the symbol table for a source file is being read; see
`symbol-file' in *Note Commands to specify files: Files.

`set verbose on'
     Enables GDB output of certain informational messages.

`set verbose off'
     Disables GDB output of certain informational messages.

`show verbose'
     Displays whether `set verbose' is on or off.

   By default, if GDB encounters bugs in the symbol table of an object
file, it is silent; but if you are debugging a compiler, you may find
this information useful (*note Errors reading symbol files: Symbol
Errors.).

`set complaints LIMIT'
     Permits GDB to output LIMIT complaints about each type of unusual
     symbols before becoming silent about the problem.  Set LIMIT to
     zero to suppress all complaints; set it to a large number to
     prevent complaints from being suppressed.

`show complaints'
     Displays how many symbol complaints GDB is permitted to produce.

   By default, GDB 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:

     (gdb) run
     The program being debugged has been started already.
     Start it from the beginning? (y or n)

   If you are willing to unflinchingly face the consequences of your own
commands, you can disable this "feature":

`set confirm off'
     Disables confirmation requests.

`set confirm on'
     Enables confirmation requests (the default).

`show confirm'
     Displays state of confirmation requests.


File: gdb.info,  Node: Sequences,  Next: Emacs,  Prev: Controlling GDB,  Up: Top

Canned Sequences of Commands
****************************

   Aside from breakpoint commands (*note Breakpoint command lists:
Break Commands.), GDB provides two ways to store sequences of commands
for execution as a unit: user-defined commands and command files.

* Menu:

* Define::                      User-defined commands
* Hooks::                       User-defined command hooks
* Command Files::               Command files
* Output::                      Commands for controlled output


File: gdb.info,  Node: Define,  Next: Hooks,  Prev: Sequences,  Up: Sequences

User-defined commands
=====================

   A "user-defined command" is a sequence of GDB commands to which you
assign a new name as a command.  This is done with the `define'
command.  User commands may accept up to 10 arguments separated by
whitespace.  Arguments are accessed within the user command via
$ARG0...$ARG9.  A trivial example:

     define adder
       print $arg0 + $arg1 + $arg2

To execute the command use:

     adder 1 2 3

This defines the command `adder', which prints the sum of its three
arguments.  Note the arguments are text substitutions, so they may
reference variables, use complex expressions, or even perform inferior
functions calls.

`define COMMANDNAME'
     Define a command named COMMANDNAME.  If there is already a command
     by that name, you are asked to confirm that you want to redefine
     it.

     The definition of the command is made up of other GDB command
     lines, which are given following the `define' command.  The end of
     these commands is marked by a line containing `end'.

`if'
     Takes a single argument, which is an expression to evaluate.  It
     is followed by a series of commands that are executed only if the
     expression is true (nonzero).  There can then optionally be a line
     `else', followed by a series of commands that are only executed if
     the expression was false.  The end of the list is marked by a line
     containing `end'.

`while'
     The syntax is similar to `if': the command takes a single argument,
     which is an expression to evaluate, and must be followed by the
     commands to execute, one per line, terminated by an `end'.  The
     commands are executed repeatedly as long as the expression
     evaluates to true.

`document COMMANDNAME'
     Document the user-defined command COMMANDNAME, so that it can be
     accessed by `help'.  The command COMMANDNAME must already be
     defined.  This command reads lines of documentation just as
     `define' reads the lines of the command definition, ending with
     `end'.  After the `document' command is finished, `help' on command
     COMMANDNAME displays the documentation you have written.

     You may use the `document' command again to change the
     documentation of a command.  Redefining the command with `define'
     does not change the documentation.

`help user-defined'
     List all user-defined commands, with the first line of the
     documentation (if any) for each.

`show user'
`show user COMMANDNAME'
     Display the GDB commands used to define COMMANDNAME (but not its
     documentation).  If no COMMANDNAME is given, display the
     definitions for all user-defined commands.

   When user-defined commands are executed, the commands of the
definition are not printed.  An error in any command stops execution of
the user-defined command.

   If used interactively, commands that would ask for confirmation
proceed without asking when used inside a user-defined command.  Many
GDB commands that normally print messages to say what they are doing
omit the messages when used in a user-defined command.


File: gdb.info,  Node: Hooks,  Next: Command Files,  Prev: Define,  Up: Sequences

User-defined command hooks
==========================

   You may define *hooks*, which are a special kind of user-defined
command.  Whenever you run the command `foo', if the user-defined
command `hook-foo' exists, it is executed (with no arguments) before
that command.

   In addition, a pseudo-command, `stop' exists.  Defining
(`hook-stop') makes the associated commands execute every time
execution stops in your program: before breakpoint commands are run,
displays are printed, or the stack frame is printed.

   For example, to ignore `SIGALRM' signals while single-stepping, but
treat them normally during normal execution, you could define:

     define hook-stop
     handle SIGALRM nopass
     end
     
     define hook-run
     handle SIGALRM pass
     end
     
     define hook-continue
     handle SIGLARM pass
     end

   You can define a hook for any single-word command in GDB, but not
for command aliases; you should define a hook for the basic command
name, e.g.  `backtrace' rather than `bt'.  If an error occurs during
the execution of your hook, execution of GDB commands stops and GDB
issues a prompt (before the command that you actually typed had a
chance to run).

   If you try to define a hook which does not match any known command,
you get a warning from the `define' command.


File: gdb.info,  Node: Command Files,  Next: Output,  Prev: Hooks,  Up: Sequences

Command files
=============

   A command file for GDB is a file of lines that are GDB commands.
Comments (lines starting with `#') may also be included.  An empty line
in a command file does nothing; it does not mean to repeat the last
command, as it would from the terminal.

   When you start GDB, it automatically executes commands from its
"init files".  These are files named `.gdbinit' on Unix, or `gdb.ini'
on DOS/Windows.  GDB reads the init file (if any) in your home
directory, then processes command line options and operands, and then
reads the init file (if any) in the current working directory.  This is
so the init file in your home directory can set options (such as `set
complaints') which affect the processing of the command line options
and operands.  The init files are not executed if you use the `-nx'
option; *note Choosing modes: Mode Options..

   On some configurations of GDB, the init file is known by a different
name (these are typically environments where a specialized form of GDB
may need to coexist with other forms, hence a different name for the
specialized version's init file).  These are the environments with
special init file names:

   * VxWorks (Wind River Systems real-time OS): `.vxgdbinit'

   * OS68K (Enea Data Systems real-time OS): `.os68gdbinit'

   * ES-1800 (Ericsson Telecom AB M68000 emulator): `.esgdbinit'

   You can also request the execution of a command file with the
`source' command:

`source FILENAME'
     Execute the command file FILENAME.

   The lines in a command file are executed sequentially.  They are not
printed as they are executed.  An error in any command terminates
execution of the command file.

   Commands that would ask for confirmation if used interactively
proceed without asking when used in a command file.  Many GDB commands
that normally print messages to say what they are doing omit the
messages when called from command files.


File: gdb.info,  Node: Output,  Prev: Command Files,  Up: Sequences

Commands for controlled output
==============================

   During the execution of a command file or a user-defined command,
normal GDB output is suppressed; the only output that appears is what is
explicitly printed by the commands in the definition.  This section
describes three commands useful for generating exactly the output you
want.

`echo TEXT'
     Print TEXT.  Nonprinting characters can be included in TEXT using
     C escape sequences, such as `\n' to print a newline.  *No newline
     is printed unless you specify one.* In addition to the standard C
     escape sequences, a backslash followed by a space stands for a
     space.  This is useful for displaying a string with spaces at the
     beginning or the end, since leading and trailing spaces are
     otherwise trimmed from all arguments.  To print ` and foo = ', use
     the command `echo \ and foo = \ '.

     A backslash at the end of TEXT can be used, as in C, to continue
     the command onto subsequent lines.  For example,

          echo This is some text\n\
          which is continued\n\
          onto several lines.\n

     produces the same output as

          echo This is some text\n
          echo which is continued\n
          echo onto several lines.\n

`output EXPRESSION'
     Print the value of EXPRESSION and nothing but that value: no
     newlines, no `$NN = '.  The value is not entered in the value
     history either.  *Note Expressions: Expressions, for more
     information on expressions.

`output/FMT EXPRESSION'
     Print the value of EXPRESSION in format FMT.  You can use the same
     formats as for `print'.  *Note Output formats: Output Formats, for
     more information.

`printf STRING, EXPRESSIONS...'
     Print the values of the EXPRESSIONS under the control of STRING.
     The EXPRESSIONS are separated by commas and may be either numbers
     or pointers.  Their values are printed as specified by STRING,
     exactly as if your program were to execute the C subroutine

          printf (STRING, EXPRESSIONS...);

     For example, you can print two values in hex like this:

          printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo

     The only backslash-escape sequences that you can use in the format
     string are the simple ones that consist of backslash followed by a
     letter.