This patch fixes hardware breakpoint regressions exposed by my fix for
"PR breakpoints/7143 - Watchpoint does not trigger when first set", at
https://sourceware.org/ml/gdb-patches/2014-03/msg00167.html
The testsuite caught them on Linux/x86_64, at least. gdb.sum:
gdb.sum:
FAIL: gdb.base/hbreak2.exp: next over recursive call
FAIL: gdb.base/hbreak2.exp: backtrace from factorial(5.1)
FAIL: gdb.base/hbreak2.exp: continue until exit at recursive next test
gdb.log:
(gdb) next
Program received signal SIGTRAP, Trace/breakpoint trap.
factorial (value=4) at ../../../src/gdb/testsuite/gdb.base/break.c:113
113 if (value > 1) { /* set breakpoint 7 here */
(gdb) FAIL: gdb.base/hbreak2.exp: next over recursive call
Actually, that patch just exposed a latent issue to "breakpoints
always-inserted off" mode, not really caused it. After that patch,
GDB no longer removes breakpoints at each internal event, thus making
some scenarios behave like breakpoint always-inserted on. The bug is
easy to trigger with always-inserted on.
The issue is that since the target-side breakpoint conditions support,
if the stub/server supports evaluating breakpoint conditions on the
target side, then GDB is sending duplicate Zx packets to the target
without removing them before, and GDBserver is not really expecting
that for Z packets other than Z0/z0. E.g., with "set breakpoint
always-inserted on" and "set debug remote 1":
(gdb) b main
Sending packet: $m410943,1#ff...Packet received: 48
Breakpoint 4 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z0,410943,1#48...Packet received: OK
^^^^^^^^^^^^
(gdb) b main
Note: breakpoint 4 also set at pc 0x410943.
Sending packet: $m410943,1#ff...Packet received: 48
Breakpoint 5 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z0,410943,1#48...Packet received: OK
^^^^^^^^^^^^
(gdb) b main
Note: breakpoints 4 and 5 also set at pc 0x410943.
Sending packet: $m410943,1#ff...Packet received: 48
Breakpoint 6 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z0,410943,1#48...Packet received: OK
^^^^^^^^^^^^
(gdb) del
Delete all breakpoints? (y or n) y
Sending packet: $Z0,410943,1#48...Packet received: OK
Sending packet: $Z0,410943,1#48...Packet received: OK
Sending packet: $z0,410943,1#68...Packet received: OK
And for Z1, similarly:
(gdb) hbreak main
Sending packet: $m410943,1#ff...Packet received: 48
Hardware assisted breakpoint 4 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z1,410943,1#49...Packet received: OK
^^^^^^^^^^^^
Packet Z1 (hardware-breakpoint) is supported
(gdb) hbreak main
Note: breakpoint 4 also set at pc 0x410943.
Sending packet: $m410943,1#ff...Packet received: 48
Hardware assisted breakpoint 5 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z1,410943,1#49...Packet received: OK
^^^^^^^^^^^^
(gdb) hbreak main
Note: breakpoints 4 and 5 also set at pc 0x410943.
Sending packet: $m410943,1#ff...Packet received: 48
Hardware assisted breakpoint 6 at 0x410943: file ../../../src/gdb/gdbserver/server.c, line 3028.
Sending packet: $Z1,410943,1#49...Packet received: OK
^^^^^^^^^^^^
(gdb) del
Delete all breakpoints? (y or n) y
Sending packet: $Z1,410943,1#49...Packet received: OK
^^^^^^^^^^^^
Sending packet: $Z1,410943,1#49...Packet received: OK
^^^^^^^^^^^^
Sending packet: $z1,410943,1#69...Packet received: OK
^^^^^^^^^^^^
So GDB sent a bunch of Z1 packets, and then when finally removing the
breakpoint, only one z1 packet was sent. On the GDBserver side (with
monitor set debug-hw-points 1), in the Z1 case, we see:
$ ./gdbserver :9999 ./gdbserver
Process ./gdbserver created; pid = 8629
Listening on port 9999
Remote debugging from host 127.0.0.1
insert_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=1 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
insert_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=2 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
insert_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=3 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
insert_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=4 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
insert_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=5 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
remove_watchpoint (addr=410943, len=1, type=instruction-execute):
CONTROL (DR7): 00000101 STATUS (DR6): 00000000
DR0: addr=0x410943, ref.count=4 DR1: addr=0x0, ref.count=0
DR2: addr=0x0, ref.count=0 DR3: addr=0x0, ref.count=0
That's one insert_watchpoint call for each Z1 packet, and then one
remove_watchpoint call for the z1 packet. Notice how ref.count
increased for each insert_watchpoint call, and then in the end, after
GDB told GDBserver to forget about the hardware breakpoint, GDBserver
ends with the the first debug register still with ref.count=4! IOW,
the hardware breakpoint is left armed on the target, while on the GDB
end it's gone. If the program happens to execute 0x410943 afterwards,
then the CPU traps, GDBserver reports the trap to GDB, and GDB not
having a breakpoint set at that address anymore, reports to the user a
spurious SIGTRAP.
This is exactly what is happening in the hbreak2.exp test, though in
that case, it's a shared library event that triggers a
breakpoint_re_set, when breakpoints are still inserted (because
nowadays GDB doesn't remove breakpoints while handling internal
events), and that recreates breakpoint locations, which likewise
forces breakpoint reinsertion and Zx packet resends...
That is a lot of bogus Zx duplication that should possibly be
addressed on the GDB side. GDB resends Zx packets because the way to
change the target-side condition, is to resend the breakpoint to the
server with the new condition. (That's an option in the packet: e.g.,
"Z1,410943,1;X3,220027" for "hbreak main if 0". The packets in the
examples above are shorter because the breakpoints don't have
conditions attached). GDB doesn't remove the breakpoint first before
reinserting it because that'd be bad for non-stop, as it'd open a
window where the inferior could miss the breakpoint. The conditions
actually haven't changed between the resends, but GDB isn't smart
enough to realize that.
(TBC, if the target doesn't support target-side conditions, then GDB
doesn't trigger these resends (init_bp_location calls
mark_breakpoint_location_modified, and that does nothing if condition
evaluation is on the host side. The resends are caused by the
'loc->condition_changed = condition_modified.' line.)
But, even if GDB was made smarter, GDBserver should really still
handle the resends anyway. So target-side conditions also aren't
really to blame. The documentation of the Z/z packets says:
"To avoid potential problems with duplicate packets, the operations
should be implemented in an idempotent way."
As such, we may want to fix GDB, but we should definitely fix
GDBserver. The fix is a prerequisite for target-side conditions on
hardware breakpoints anyway (and while at it, on watchpoints too).
GDBserver indeed already treats duplicate Z0 packets in an idempotent
way. mem-break.c has the concept of high-level and low-level
breakpoints, somewhat similar to GDB's split of breakpoints vs
breakpoint locations, and keeps track of multiple breakpoints
referencing the same address/location, for the case of an internal
GDBserver breakpoint or a tracepoint being set at the same address as
a GDB breakpoint. But, it only allows GDB to ever contribute one
reference to a software breakpoint location. IOW, if gdbserver sees a
Z0 packet for the same address where it already had a GDB breakpoint
set, then GDBserver won't create another high-level GDB breakpoint.
However, mem-break.c only tracks GDB Z0 breakpoints. The same logic
should apply to all kinds of Zx packets. Currently, gdbserver passes
down each duplicate Zx (other than Z0) request directly to the
target->insert_point routine. The x86 watchpoint support itself
refcounts watchpoint / hw breakpoint requests, to handle overlapping
watchpoints, and save debug registers. But that code doesn't (and
really shouldn't) handle the duplicate requests, assuming that for
each insert there will be a corresponding remove.
So the fix is to generalize mem-break.c to track all kinds of Zx
breakpoints, and filter out duplicates. As mentioned, this ends up
adding support for target-side conditions on hardware breakpoints and
watchpoints too (though GDB itself doesn't support the latter yet).
Probably the least obvious change in the patch is that it kind of
turns the breakpoint insert/remove APIs inside out. Before, the
target methods were only called for GDB breakpoints. The internal
breakpoint set/delete methods inserted memory breakpoints directly
bypassing the insert/remove target methods. That's not good when the
target should use a debug API to set software breakpoints, instead of
relying on GDBserver patching memory with breakpoint instructions, as
is the case of NTO.
Now removal/insertion of all kinds of breakpoints/watchpoints, either
internal, or from GDB, always go through the target methods. The
insert_point/remove_point methods no longer get passed a Z packet
type, but an internal/raw breakpoint type. They're also passed a
pointer to the raw breakpoint itself (note that's still opaque outside
mem-break.c), so that insert_memory_breakpoint /
remove_memory_breakpoint have access to the breakpoint's shadow
buffer. I first tried passing down a new structure based on GDB's
"struct bp_target_info" (actually with that name exactly), but then
decided against it as unnecessary complication.
As software/memory breakpoints work by poking at memory, when setting
a GDB Z0 breakpoint (but not internal breakpoints, as those can assume
the conditions are already right), we need to tell the target to
prepare to access memory (which on Linux means stop threads). If that
operation fails, we need to return error to GDB. Seeing an error, if
this is the first breakpoint of that type that GDB tries to insert,
GDB would then assume the breakpoint type is supported, but it may
actually not be. So we need to check whether the type is supported at
all before preparing to access memory. And to solve that, the patch
adds a new target->supports_z_point_type method that is called before
actually trying to insert the breakpoint.
Other than that, hopefully the change is more or less obvious.
New test added that exercises the hbreak2.exp regression in a more
direct way, without relying on a breakpoint re-set happening before
main is reached.
Tested by building GDBserver for:
aarch64-linux-gnu
arm-linux-gnueabihf
i686-pc-linux-gnu
i686-w64-mingw32
m68k-linux-gnu
mips-linux-gnu
mips-uclinux
nios2-linux-gnu
powerpc-linux-gnu
sh-linux-gnu
tilegx-unknown-linux-gnu
x86_64-redhat-linux
x86_64-w64-mingw32
And also regression tested on x86_64 Fedora 20.
gdb/gdbserver/
2014-05-20 Pedro Alves <palves@redhat.com>
* linux-aarch64-low.c (aarch64_insert_point)
(aarch64_remove_point): No longer check whether the type is
supported here. Adjust to new interface.
(the_low_target): Install aarch64_supports_z_point_type as
supports_z_point_type method.
* linux-arm-low.c (raw_bkpt_type_to_arm_hwbp_type): New function.
(arm_linux_hw_point_initialize): Take an enum raw_bkpt_type
instead of a Z packet char. Adjust.
(arm_supports_z_point_type): New function.
(arm_insert_point, arm_remove_point): Adjust to new interface.
(the_low_target): Install arm_supports_z_point_type.
* linux-crisv32-low.c (cris_supports_z_point_type): New function.
(cris_insert_point, cris_remove_point): Adjust to new interface.
Don't check whether the type is supported here.
(the_low_target): Install cris_supports_z_point_type.
* linux-low.c (linux_supports_z_point_type): New function.
(linux_insert_point, linux_remove_point): Adjust to new interface.
* linux-low.h (struct linux_target_ops) <insert_point,
remove_point>: Take an enum raw_bkpt_type instead of a char. Add
raw_breakpoint pointer parameter.
<supports_z_point_type>: New method.
* linux-mips-low.c (mips_supports_z_point_type): New function.
(mips_insert_point, mips_remove_point): Adjust to new interface.
Use mips_supports_z_point_type.
(the_low_target): Install mips_supports_z_point_type.
* linux-ppc-low.c (the_low_target): Install NULL as
supports_z_point_type method.
* linux-s390-low.c (the_low_target): Install NULL as
supports_z_point_type method.
* linux-sparc-low.c (the_low_target): Install NULL as
supports_z_point_type method.
* linux-x86-low.c (x86_supports_z_point_type): New function.
(x86_insert_point): Adjust to new insert_point interface. Use
insert_memory_breakpoint. Adjust to new
i386_low_insert_watchpoint interface.
(x86_remove_point): Adjust to remove_point interface. Use
remove_memory_breakpoint. Adjust to new
i386_low_remove_watchpoint interface.
(the_low_target): Install x86_supports_z_point_type.
* lynx-low.c (lynx_target_ops): Install NULL as
supports_z_point_type callback.
* nto-low.c (nto_supports_z_point_type): New.
(nto_insert_point, nto_remove_point): Adjust to new interface.
(nto_target_ops): Install nto_supports_z_point_type.
* mem-break.c: Adjust intro comment.
(struct raw_breakpoint) <raw_type, size>: New fields.
<inserted>: Update comment.
<shlib_disabled>: Delete field.
(enum bkpt_type) <gdb_breakpoint>: Delete value.
<gdb_breakpoint_Z0, gdb_breakpoint_Z1, gdb_breakpoint_Z2,
gdb_breakpoint_Z3, gdb_breakpoint_Z4>: New values.
(raw_bkpt_type_to_target_hw_bp_type): New function.
(find_enabled_raw_code_breakpoint_at): New function.
(find_raw_breakpoint_at): New type and size parameters. Use them.
(insert_memory_breakpoint): New function, based off
set_raw_breakpoint_at.
(remove_memory_breakpoint): New function.
(set_raw_breakpoint_at): Reimplement.
(set_breakpoint): New, based on set_breakpoint_at.
(set_breakpoint_at): Reimplement.
(delete_raw_breakpoint): Go through the_target->remove_point
instead of assuming memory breakpoints.
(find_gdb_breakpoint_at): Delete.
(Z_packet_to_bkpt_type, Z_packet_to_raw_bkpt_type): New functions.
(find_gdb_breakpoint): New function.
(set_gdb_breakpoint_at): Delete.
(z_type_supported): New function.
(set_gdb_breakpoint_1): New function, loosely based off
set_gdb_breakpoint_at.
(check_gdb_bp_preconditions, set_gdb_breakpoint): New functions.
(delete_gdb_breakpoint_at): Delete.
(delete_gdb_breakpoint_1): New function, loosely based off
delete_gdb_breakpoint_at.
(delete_gdb_breakpoint): New function.
(clear_gdb_breakpoint_conditions): Rename to ...
(clear_breakpoint_conditions): ... this. Don't handle a NULL
breakpoint.
(add_condition_to_breakpoint): Make static.
(add_breakpoint_condition): Take a struct breakpoint pointer
instead of an address. Adjust.
(gdb_condition_true_at_breakpoint): Rename to ...
(gdb_condition_true_at_breakpoint_z_type): ... this, and add
z_type parameter.
(gdb_condition_true_at_breakpoint): Reimplement.
(add_breakpoint_commands): Take a struct breakpoint pointer
instead of an address. Adjust.
(gdb_no_commands_at_breakpoint): Rename to ...
(gdb_no_commands_at_breakpoint_z_type): ... this. Add z_type
parameter. Return true if no breakpoint was found. Change debug
output.
(gdb_no_commands_at_breakpoint): Reimplement.
(run_breakpoint_commands): Rename to ...
(run_breakpoint_commands_z_type): ... this. Add z_type parameter,
and change return type to boolean.
(run_breakpoint_commands): New function.
(gdb_breakpoint_here): Also check for Z1 breakpoints.
(uninsert_raw_breakpoint): Don't try to reinsert a disabled
breakpoint. Go through the_target->remove_point instead of
assuming memory breakpoint.
(uninsert_breakpoints_at, uninsert_all_breakpoints): Uninsert
software and hardware breakpoints.
(reinsert_raw_breakpoint): Go through the_target->insert_point
instead of assuming memory breakpoint.
(reinsert_breakpoints_at, reinsert_all_breakpoints): Reinsert
software and hardware breakpoints.
(check_breakpoints, breakpoint_here, breakpoint_inserted_here):
Check both software and hardware breakpoints.
(validate_inserted_breakpoint): Assert the breakpoint is a
software breakpoint. Set the inserted flag to -1 instead of
setting shlib_disabled.
(delete_disabled_breakpoints): Adjust.
(validate_breakpoints): Only validate software breakpoints.
Adjust to inserted flag change.
(check_mem_read, check_mem_write): Skip breakpoint types other
than software breakpoints. Adjust to inserted flag change.
* mem-break.h (enum raw_bkpt_type): New enum.
(raw_breakpoint, struct process_info): Forward declare.
(Z_packet_to_target_hw_bp_type): Delete declaration.
(raw_bkpt_type_to_target_hw_bp_type, Z_packet_to_raw_bkpt_type)
(set_gdb_breakpoint, delete_gdb_breakpoint)
(clear_breakpoint_conditions): New declarations.
(set_gdb_breakpoint_at, clear_gdb_breakpoint_conditions): Delete.
(breakpoint_inserted_here): Update comment.
(add_breakpoint_condition, add_breakpoint_commands): Replace
address parameter with a breakpoint pointer parameter.
(gdb_breakpoint_here): Update comment.
(delete_gdb_breakpoint_at): Delete.
(insert_memory_breakpoint, remove_memory_breakpoint): Declare.
* server.c (process_point_options): Take a struct breakpoint
pointer instead of an address. Adjust.
(process_serial_event) <Z/z packets>: Use set_gdb_breakpoint and
delete_gdb_breakpoint.
* spu-low.c (spu_target_ops): Install NULL as
supports_z_point_type method.
* target.h: Include mem-break.h.
(struct target_ops) <prepare_to_access_memory>: Update comment.
<supports_z_point_type>: New field.
<insert_point, remove_point>: Take an enum raw_bkpt_type argument
instead of a char. Also take a raw breakpoint pointer.
* win32-arm-low.c (the_low_target): Install NULL as
supports_z_point_type.
* win32-i386-low.c (i386_supports_z_point_type): New function.
(i386_insert_point, i386_remove_point): Adjust to new interface.
(the_low_target): Install i386_supports_z_point_type.
* win32-low.c (win32_supports_z_point_type): New function.
(win32_insert_point, win32_remove_point): Adjust to new interface.
(win32_target_ops): Install win32_supports_z_point_type.
* win32-low.h (struct win32_target_ops):
<supports_z_point_type>: New method.
<insert_point, remove_point>: Take an enum raw_bkpt_type argument
instead of a char. Also take a raw breakpoint pointer.
gdb/testsuite/
2014-05-20 Pedro Alves <palves@redhat.com>
* gdb.base/break-idempotent.c: New file.
* gdb.base/break-idempotent.exp: New file.
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make doc/gdb.dvi
If you prefer to have the manual in PDF format, type this from the
`gdb/doc' subdirectory of the main source directory:
make gdb.pdf
For this to work, you will need the PDFTeX package to be installed.
Installing GDB
**************
GDB comes with a `configure' script that automates the process of
preparing GDB for installation; you can then use `make' to build the
`gdb' program.
The GDB distribution includes all the source code you need for GDB in
a single directory. That directory contains:
`gdb-VERSION/{COPYING,COPYING.LIB}'
Standard GNU license files. Please read them.
`gdb-VERSION/bfd'
source for the Binary File Descriptor library
`gdb-VERSION/config*'
script for configuring GDB, along with other support files
`gdb-VERSION/gdb'
the source specific to GDB itself
`gdb-VERSION/include'
GNU include files
`gdb-VERSION/libiberty'
source for the `-liberty' free software library
`gdb-VERSION/opcodes'
source for the library of opcode tables and disassemblers
`gdb-VERSION/readline'
source for the GNU command-line interface
NOTE: The readline library is compiled for use by GDB, but will
not be installed on your system when "make install" is issued.
`gdb-VERSION/sim'
source for some simulators (ARM, D10V, SPARC, M32R, MIPS, PPC, V850, etc)
`gdb-VERSION/texinfo'
The `texinfo.tex' file, which you need in order to make a printed
manual using TeX.
`gdb-VERSION/etc'
Coding standards, useful files for editing GDB, and other
miscellanea.
Note: the following instructions are for building GDB on Unix or
Unix-like systems. Instructions for building with DJGPP for
MS-DOS/MS-Windows are in the file gdb/config/djgpp/README.
The simplest way to configure and build GDB is to run `configure'
from the `gdb-VERSION' directory.
First switch to the `gdb-VERSION' source directory if you are
not already in it; then run `configure'.
For example:
cd gdb-VERSION
./configure
make
Running `configure' followed by `make' builds the `bfd',
`readline', `mmalloc', and `libiberty' libraries, then `gdb' itself.
The configured source files, and the binaries, are left in the
corresponding source directories.
`configure' is a Bourne-shell (`/bin/sh') script; if your system
does not recognize this automatically when you run a different shell,
you may need to run `sh' on it explicitly:
sh configure
If you run `configure' from a directory that contains source
directories for multiple libraries or programs, `configure' creates
configuration files for every directory level underneath (unless
you tell it not to, with the `--norecursion' option).
You can install `gdb' anywhere; it has no hardwired paths. However,
you should make sure that the shell on your path (named by the `SHELL'
environment variable) is publicly readable. Remember that GDB uses the
shell to start your program--some systems refuse to let GDB debug child
processes whose programs are not readable.
Compiling GDB in another directory
==================================
If you want to run GDB versions for several host or target machines,
you need a different `gdb' compiled for each combination of host and
target. `configure' is designed to make this easy by allowing you to
generate each configuration in a separate subdirectory, rather than in
the source directory. If your `make' program handles the `VPATH'
feature correctly (GNU `make' and SunOS 'make' are two that should),
running `make' in each of these directories builds the `gdb' program
specified there.
To build `gdb' in a separate directory, run `configure' with the
`--srcdir' option to specify where to find the source. (You also need
to specify a path to find `configure' itself from your working
directory. If the path to `configure' would be the same as the
argument to `--srcdir', you can leave out the `--srcdir' option; it
will be assumed.)
For example, you can build GDB in a separate
directory for a Sun 4 like this:
cd gdb-VERSION
mkdir ../gdb-sun4
cd ../gdb-sun4
../gdb-VERSION/configure
make
When `configure' builds a configuration using a remote source
directory, it creates a tree for the binaries with the same structure
(and using the same names) as the tree under the source directory. In
the example, you'd find the Sun 4 library `libiberty.a' in the
directory `gdb-sun4/libiberty', and GDB itself in `gdb-sun4/gdb'.
One popular reason to build several GDB configurations in separate
directories is to configure GDB for cross-compiling (where GDB runs on
one machine--the host--while debugging programs that run on another
machine--the target). You specify a cross-debugging target by giving
the `--target=TARGET' option to `configure'.
When you run `make' to build a program or library, you must run it
in a configured directory--whatever directory you were in when you
called `configure' (or one of its subdirectories).
The `Makefile' that `configure' generates in each source directory
also runs recursively. If you type `make' in a source directory such
as `gdb-VERSION' (or in a separate configured directory configured with
`--srcdir=PATH/gdb-VERSION'), you will build all the required libraries,
and then build GDB.
When you have multiple hosts or targets configured in separate
directories, you can run `make' on them in parallel (for example, if
they are NFS-mounted on each of the hosts); they will not interfere
with each other.
Specifying names for hosts and targets
======================================
The specifications used for hosts and targets in the `configure'
script are based on a three-part naming scheme, but some short
predefined aliases are also supported. The full naming scheme encodes
three pieces of information in the following pattern:
ARCHITECTURE-VENDOR-OS
For example, you can use the alias `sun4' as a HOST argument or in a
`--target=TARGET' option. The equivalent full name is
`sparc-sun-sunos4'.
The `configure' script accompanying GDB does not provide any query
facility to list all supported host and target names or aliases.
`configure' calls the Bourne shell script `config.sub' to map
abbreviations to full names; you can read the script, if you wish, or
you can use it to test your guesses on abbreviations--for example:
% sh config.sub sun4
sparc-sun-sunos4.1.1
% sh config.sub sun3
m68k-sun-sunos4.1.1
% sh config.sub decstation
mips-dec-ultrix4.2
% sh config.sub hp300bsd
m68k-hp-bsd
% sh config.sub i386v
i386-pc-sysv
% sh config.sub i786v
Invalid configuration `i786v': machine `i786v' not recognized
`config.sub' is also distributed in the GDB source directory.
`configure' options
===================
Here is a summary of the `configure' options and arguments that are
most often useful for building GDB. `configure' also has several other
options not listed here. *note : (configure.info)What Configure Does,
for a full explanation of `configure'.
configure [--help]
[--prefix=DIR]
[--srcdir=PATH]
[--norecursion] [--rm]
[--enable-build-warnings]
[--target=TARGET]
[--host=HOST]
[HOST]
You may introduce options with a single `-' rather than `--' if you
prefer; but you may abbreviate option names if you use `--'.
`--help'
Display a quick summary of how to invoke `configure'.
`-prefix=DIR'
Configure the source to install programs and files under directory
`DIR'.
`--srcdir=PATH'
*Warning: using this option requires GNU `make', or another `make'
that compatibly implements the `VPATH' feature.*
Use this option to make configurations in directories separate
from the GDB source directories. Among other things, you can use
this to build (or maintain) several configurations simultaneously,
in separate directories. `configure' writes configuration
specific files in the current directory, but arranges for them to
use the source in the directory PATH. `configure' will create
directories under the working directory in parallel to the source
directories below PATH.
`--host=HOST'
Configure GDB to run on the specified HOST.
There is no convenient way to generate a list of all available
hosts.
`HOST ...'
Same as `--host=HOST'. If you omit this, GDB will guess; it's
quite accurate.
`--norecursion'
Configure only the directory level where `configure' is executed;
do not propagate configuration to subdirectories.
`--rm'
Remove the configuration that the other arguments specify.
`--enable-build-warnings'
When building the GDB sources, ask the compiler to warn about any
code which looks even vaguely suspicious. You should only using
this feature if you're compiling with GNU CC. It passes the
following flags:
-Wimplicit
-Wreturn-type
-Wcomment
-Wtrigraphs
-Wformat
-Wparentheses
-Wpointer-arith
`--enable-werror'
Treat compiler warnings as werrors. Use this only with GCC. It
adds the -Werror flag to the compiler, which will fail the
compilation if the compiler outputs any warning messages.
`--target=TARGET'
Configure GDB for cross-debugging programs running on the specified
TARGET. Without this option, GDB is configured to debug programs
that run on the same machine (HOST) as GDB itself.
There is no convenient way to generate a list of all available
targets.
`--with-gdb-datadir=PATH'
Set the GDB-specific data directory. GDB will look here for
certain supporting files or scripts. This defaults to the `gdb'
subdirectory of `datadir' (which can be set using `--datadir').
`--with-relocated-sources=DIR'
Sets up the default source path substitution rule so that
directory names recorded in debug information will be
automatically adjusted for any directory under DIR. DIR should
be a subdirectory of GDB's configured prefix, the one mentioned
in the `--prefix' or `--exec-prefix' options to configure. This
option is useful if GDB is supposed to be moved to a different
place after it is built.
`--enable-64-bit-bfd'
Enable 64-bit support in BFD on 32-bit hosts.
`--disable-gdbmi'
Build GDB without the GDB/MI machine interface.
`--enable-tui'
Build GDB with the text-mode full-screen user interface (TUI).
Requires a curses library (ncurses and cursesX are also
supported).
`--enable-gdbtk'
Build GDB with the gdbtk GUI interface. Requires TCL/Tk to be
installed.
`--with-libunwind-ia64'
Use the libunwind library for unwinding function call stack on ia64
target platforms.
See http://www.nongnu.org/libunwind/index.html for details.
`--with-curses'
Use the curses library instead of the termcap library, for
text-mode terminal operations.
`--enable-profiling' Enable profiling of GDB itself. Necessary if you
want to use the "maint set profile" command for profiling GDB.
Requires the functions `monstartup' and `_mcleanup' to be present
in the standard C library used to build GDB, and also requires a
compiler that supports the `-pg' option.
`--with-system-readline'
Use the readline library installed on the host, rather than the
library supplied as part of GDB tarball.
`--with-expat'
Build GDB with the libexpat library. (Done by default if
libexpat is installed and found at configure time.) This library
is used to read XML files supplied with GDB. If it is
unavailable, some features, such as remote protocol memory maps,
target descriptions, and shared library lists, that are based on
XML files, will not be available in GDB. If your host does not
have libexpat installed, you can get the latest version from
http://expat.sourceforge.net.
`--with-python[=PATH]'
Build GDB with Python scripting support. (Done by default if
libpython is present and found at configure time.) Python makes
GDB scripting much more powerful than the restricted CLI
scripting language. If your host does not have Python installed,
you can find it on http://www.python.org/download/. The oldest
version of Python supported by GDB is 2.4. The optional argument
PATH says where to find the Python headers and libraries; the
configure script will look in PATH/include for headers and in
PATH/lib for the libraries.
`--without-included-regex'
Don't use the regex library included with GDB (as part of the
libiberty library). This is the default on hosts with version 2
of the GNU C library.
`--with-sysroot=DIR'
Use DIR as the default system root directory for libraries whose
file names begin with `/lib' or `/usr/lib'. (The value of DIR
can be modified at run time by using the "set sysroot" command.)
If DIR is under the GDB configured prefix (set with `--prefix' or
`--exec-prefix' options), the default system root will be
automatically adjusted if and when GDB is moved to a different
location.
`--with-system-gdbinit=FILE'
Configure GDB to automatically load a system-wide init file.
FILE should be an absolute file name. If FILE is in a directory
under the configured prefix, and GDB is moved to another location
after being built, the location of the system-wide init file will
be adjusted accordingly.
`configure' accepts other options, for compatibility with configuring
other GNU tools recursively; but these are the only options that affect
GDB or its supporting libraries.
Remote debugging
=================
The files m68k-stub.c, i386-stub.c, and sparc-stub.c are examples
of remote stubs to be used with remote.c. They are designed to run
standalone on an m68k, i386, or SPARC cpu and communicate properly
with the remote.c stub over a serial line.
The directory gdb/gdbserver/ contains `gdbserver', a program that
allows remote debugging for Unix applications. GDBserver is only
supported for some native configurations, including Sun 3, Sun 4, and
Linux.
The file gdb/gdbserver/README includes further notes on GDBserver; in
particular, it explains how to build GDBserver for cross-debugging
(where GDBserver runs on the target machine, which is of a different
architecture than the host machine running GDB).
There are a number of remote interfaces for talking to existing ROM
monitors and other hardware:
remote-mips.c MIPS remote debugging protocol
remote-sds.c PowerPC SDS monitor
remote-sim.c Generalized simulator protocol
Reporting Bugs in GDB
=====================
There are several ways of reporting bugs in GDB. The prefered
method is to use the World Wide Web:
http://www.gnu.org/software/gdb/bugs/
As an alternative, the bug report can be submitted, via e-mail, to the
address "bug-gdb@gnu.org".
When submitting a bug, please include the GDB version number, and
how you configured it (e.g., "sun4" or "mach386 host,
i586-intel-synopsys target"). Since GDB now supports so many
different configurations, it is important that you be precise about
this. If at all possible, you should include the actual banner
that GDB prints when it starts up, or failing that, the actual
configure command that you used when configuring GDB.
For more information on how/whether to report bugs, see the
Reporting Bugs chapter of the GDB manual (gdb/doc/gdb.texinfo).
Graphical interface to GDB -- X Windows, MS Windows
==========================
Several graphical interfaces to GDB are available. You should
check:
http://www.gnu.org/software/gdb/links/
for an up-to-date list.
Emacs users will very likely enjoy the Grand Unified Debugger mode;
try typing `M-x gdb RET'.
Writing Code for GDB
=====================
There is information about writing code for GDB in the file
`CONTRIBUTE' and at the website:
http://www.gnu.org/software/gdb/
in particular in the wiki.
If you are pondering writing anything but a short patch, especially
take note of the information about copyrights and copyright assignment.
It can take quite a while to get all the paperwork done, so
we encourage you to start that process as soon as you decide you are
planning to work on something, or at least well ahead of when you
think you will be ready to submit the patches.
GDB Testsuite
=============
Included with the GDB distribution is a DejaGNU based testsuite
that can either be used to test your newly built GDB, or for
regression testing a GDB with local modifications.
Running the testsuite requires the prior installation of DejaGNU,
which is generally available via ftp. The directory
ftp://sources.redhat.com/pub/dejagnu/ will contain a recent snapshot.
Once DejaGNU is installed, you can run the tests in one of the
following ways:
(1) cd gdb-VERSION
make check-gdb
or
(2) cd gdb-VERSION/gdb
make check
or
(3) cd gdb-VERSION/gdb/testsuite
make site.exp (builds the site specific file)
runtest -tool gdb GDB=../gdb (or GDB=<somepath> as appropriate)
When using a `make'-based method, you can use the Makefile variable
`RUNTESTFLAGS' to pass flags to `runtest', e.g.:
make RUNTESTFLAGS=--directory=gdb.cp check
If you use GNU make, you can use its `-j' option to run the testsuite
in parallel. This can greatly reduce the amount of time it takes for
the testsuite to run. In this case, if you set `RUNTESTFLAGS' then,
by default, the tests will be run serially even under `-j'. You can
override this and force a parallel run by setting the `make' variable
`FORCE_PARALLEL' to any non-empty value. Note that the parallel `make
check' assumes that you want to run the entire testsuite, so it is not
compatible with some dejagnu options, like `--directory'.
The last method gives you slightly more control in case of problems
with building one or more test executables or if you are using the
testsuite `standalone', without it being part of the GDB source tree.
See the DejaGNU documentation for further details.
Copyright and License Notices
=============================
Most files maintained by the GDB Project contain a copyright notice
as well as a license notice, usually at the start of the file.
To reduce the length of copyright notices, consecutive years in the
copyright notice can be combined into a single range. For instance,
the following list of copyright years...
1986, 1988, 1989, 1991-1993, 1999, 2000, 2007, 2008, 2009, 2010, 2011
... is abbreviated into:
1986, 1988-1989, 1991-1993, 1999-2000, 2007-2011
Every year of each range, inclusive, is a copyrightable year that
could be listed individually.
(this is for editing this file with GNU emacs)
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