GDB 6.2 Released

GDB 6.2 Released

[Andrew Cagney]

			GDB 6.2 released!

Version 6.2 of GDB, the GNU Debugger, is now available via anonymous
FTP.  GDB is a source-level debugger for C, C++, Java and many other
languages.  GDB can target (i.e., debug programs running on) more than
a dozen different processor architectures, and GDB itself can run on
most popular GNU/Linux, Unix and Microsoft Windows variants.

You can download GDB from Project GNU's FTP server in the directory:

	ftp://ftp.gnu.org/gnu/gdb

The previous version, 6.1.1, was released roughly 1 months ago; and in
that time several new features have been added and many bugs have been
fixed.  The details are below.  In addition, a number of late breaking
problems have been identified and they are also mentioned below.

The vital stats: 

	Size      md5sum                            Name
	17011120  c095d01e55022fb9e609df5cfde66379  gdb-6.2.tar.gz
	12819441  01871f7667345262e317a1e6e1a32768  gdb-6.2.tar.bz2

There is a web page for GDB at: 

	http://www.gnu.org/software/gdb/

That page includes information about GDB mailing lists (an
announcement mailing list, developers discussion lists, etc.), details
on how to access GDB's CVS repository, locations for development
snapshots, preformatted documentation, and links to related
information around the net.  We will put errata notes and
host-specific tips for this release on-line as any problems come up.
All mailing lists archives are also browsable via the web.

The credit must go to Alan Modra, Albert Chin-A-Young, Alexandre
Oliva, Andreas Schwab, Andrew Cagney, Bob Rossi, Brian Ford, Bryce
McKinlay, Corinna Vinschen, Daniel Jacobowitz, David Anderson, David
Carlton, Elena Zannoni, Guy Martin, J. Brobecker, Jason Molenda, Jeff
Johnston, Jerome Guitton, Jim Blandy, Jim Ingham, Joel Brobecker,
Kevin Buettner, Maciej W. Rozycki, Mark Kettenis, Martin Hunt, Michael
Chastain, Michael Snyder, Nathan J. Williams, Nick Roberts, Orjan
Friberg, Paul Brook, Paul N. Hilfinger, Rainer Orth, Randolph Chung,
Roland McGrath, and Ulrich Weigand.

Keep those fixes and improvements coming in! (See
http://www.gnu.org/software/gdb/bugs/)

       Andrew Cagney
\f
		What has changed in GDB?
	     (Organized release by release)

*** Changes in GDB 6.2:

* Fix for ``many threads''

On GNU/Linux systems that use the NPTL threads library, a program
rapidly creating and deleting threads would confuse GDB leading to the
error message:

	ptrace: No such process.
	thread_db_get_info: cannot get thread info: generic error

This problem has been fixed.

* "-async" and "-noasync" options removed.

Support for the broken "-noasync" option has been removed (it caused
GDB to dump core).

* New ``start'' command.

This command runs the program until the begining of the main procedure.

* New BSD Kernel Data Access Library (libkvm) interface

Using ``target kvm'' it is now possible to debug kernel core dumps and
live kernel memory images on various FreeBSD, NetBSD and OpenBSD
platforms.  Currently supported (native-only) configurations are:

FreeBSD/amd64			x86_64-*-freebsd*
FreeBSD/i386			i?86-*-freebsd*
NetBSD/i386			i?86-*-netbsd*
NetBSD/m68k			m68*-*-netbsd*
NetBSD/sparc			sparc-*-netbsd*
OpenBSD/amd64			x86_64-*-openbsd*
OpenBSD/i386			i?86-*-openbsd*
OpenBSD/m68k			m68*-openbsd*
OpenBSD/sparc			sparc-*-openbsd*

* Signal trampoline code overhauled

Many generic problems with GDB's signal handling code have been fixed.
These include: backtraces through non-contiguous stacks; recognition
of sa_sigaction signal trampolines; backtrace from a NULL pointer
call; backtrace through a signal trampoline; step into and out of
signal handlers; and single-stepping in the signal trampoline.

Please note that kernel bugs are a limiting factor here.  These
features have been shown to work on an s390 GNU/Linux system that
include a 2.6.8-rc1 kernel.  Ref PR breakpoints/1702.

* Cygwin support for DWARF 2 added.

* New native configurations

GNU/Linux/hppa					hppa*-*-linux*
OpenBSD/hppa					hppa*-*-openbsd*
OpenBSD/m68k					m68*-*-openbsd*
OpenBSD/m88k					m88*-*-openbsd*
OpenBSD/powerpc					powerpc-*-openbsd*
NetBSD/vax					vax-*-netbsd*
OpenBSD/vax					vax-*-openbsd*

* END-OF-LIFE frame compatibility module

GDB's internal frame infrastructure has been completely rewritten.
The new infrastructure making it possible to support key new features
including DWARF 2 Call Frame Information.  To aid in the task of
migrating old configurations to this new infrastructure, a
compatibility module, that allowed old configurations to continue to
work, was also included.

GDB 6.2 will be the last release to include this frame compatibility
module.  This change directly impacts the following configurations:

h8300-*-*
mcore-*-*
mn10300-*-*
ns32k-*-*
sh64-*-*
v850-*-*
xstormy16-*-*

Unless there is activity to revive these configurations, they will be
made OBSOLETE in GDB 6.3, and REMOVED from GDB 6.4.

* REMOVED configurations and files

Sun 3, running SunOS 3				m68*-*-sunos3*
Sun 3, running SunOS 4				m68*-*-sunos4*
Sun 2, running SunOS 3				m68000-*-sunos3*
Sun 2, running SunOS 4				m68000-*-sunos4*
Motorola 680x0 running LynxOS			m68*-*-lynxos*
AT&T 3b1/Unix pc				m68*-att-*
Bull DPX2 (68k, System V release 3)		m68*-bull-sysv*
decstation					mips-dec-* mips-little-*
riscos						mips-*-riscos* mips-*-sysv*
sonymips					mips-sony-*
sysv					mips*-*-sysv4* (IRIX 5/6 not included)
\f

			Known problems in GDB 6.2

		See also: http://www.gnu.org/software/gdb/bugs/

*** MIPS native

Due to problems with both BFD (sections not being correctly
recognized) and GDB (backtraces failing), GDB 6.2 does not work on
native MIPS systems.

This will be fixed in the next update.

*** Build problems

build/1458: compile failed on hpux11

GDB has build problems on HP/UX 11 with some versions of the HP
Ansi C compiler.  (GCC works fine).

The problem happens when compiling intl/bindtextdom.c.
The error is:

  cc: "gettextP.h", line 50: error 1000: Unexpected symbol: "SWAP".
  cc: panic 2017: Cannot recover from earlier errors, terminating.
  *** Error exit code 1

This is a problem with the 'inline' keyword in gettextP.h.
The workaround is to disable 'inline' before building gdb:

  export ac_cv_c_inline=no

This problem happens only with some versions of the HP Ansi C compiler.
Versions A.11.01.25171.GP and B.11.11.28706.GP have both been observed
to work; version B.11.11.04 gets the build error and needs the
workaround.

This problem might also happen with other C compilers.

*** Misc

gdb/1560: Control-C does not always interrupt GDB.

When GDB is busy processing a command which takes a long time to
complete, hitting Control-C does not have the expected effect.
The command execution is not aborted, and the "QUIT" message confirming
the abortion is displayed only after the command has been completed.

*** C++ support

gdb/931: GDB could be more generous when reading types C++ templates on input

When the user types a template, GDB frequently requires the type to be
typed in a certain way (e.g. "const char*" as opposed to "const char *"
or "char const *" or "char const*").

gdb/1512: no canonical way to output names of C++ types

We currently don't have any canonical way to output names of C++ types.
E.g. "const char *" versus "char const *"; more subtleties arise when
dealing with templates.

gdb/1516: [regression] local classes, gcc 2.95.3, dwarf-2

With gcc 2.95.3 and the dwarf-2 debugging format, classes which are
defined locally to a function include the demangled name of the function
as part of their name.  For example, if a function "foobar" contains a
local class definition "Local", gdb will say that the name of the class
type is "foobar__Fi.0:Local".

This applies only to classes where the class type is defined inside a
function, not to variables defined with types that are defined somewhere
outside any function (which most types are).

gdb/1588: names of c++ nested types in casts must be enclosed in quotes

You must type
  (gdb) print ('Foo::Bar') x
or
  (gdb) print ('Foo::Bar' *) y
instead of
  (gdb) print (Foo::Bar) x
or
  (gdb) print (Foo::Bar *) y
respectively.

gdb/1091: Constructor breakpoints ignored
gdb/1193: g++ 3.3 creates multiple constructors: gdb 5.3 can't set breakpoints

When gcc 3.x compiles a C++ constructor or C++ destructor, it generates
2 or 3 different versions of the object code.  These versions have
unique mangled names (they have to, in order for linking to work), but
they have identical source code names, which leads to a great deal of
confusion.  Specifically, if you set a breakpoint in a constructor or a
destructor, gdb will put a breakpoint in one of the versions, but your
program may execute the other version.  This makes it impossible to set
breakpoints reliably in constructors or destructors.

gcc 3.x generates these multiple object code functions in order to
implement virtual base classes.  gcc 2.x generated just one object code
function with a hidden parameter, but gcc 3.x conforms to a multi-vendor
ABI for C++ which requires multiple object code functions.

*** Signal handlers

On many systems an attempt to single-step a system-call instruction
results in two or more instructions being executed (the system-call,
and one or more instructions following).

When attempting to single-step through a signal trampoline, this
problem may result the program unintentionally running to completion,
or re-execute the faulting instruction, or even corrupting the program
counter.

Ref: PR breakpoints/1702.

*** Stack backtraces

GDB's core code base has been updated to use a new backtrace
mechanism.  This mechanism makes it possible to support new features
such DWARF 2 Call Frame Information (which in turn makes possible
backtraces through optimized code).

Since this code is new, it is known to still have a few problems:

gdb/1505: [regression] gdb prints a bad backtrace for a thread

When backtracing a thread, gdb does not stop when it reaches the
outermost frame, instead continuing until it hits garbage.  This is
sensitive to the operating system and thread library.

*** Threads

threads/1650: manythreads.exp

On GNU/Linux systems that use the old LinuxThreads thread library, a
program rapidly creating and deleting threads can confuse GDB leading
to an internal error.

This problem does not occur on newer systems that use the NPTL
library, and did not occur with GDB 6.1.