Fork of the libunwind official github repo —

Dave Watson a77b0cd7bd Bump version to v1.2.1 3 years ago
aux c6a529d390 mvdir 16 years ago
doc ec262e127b siglongjmp documentation fix 8 years ago
include 620d1c3b0b Add aarch64 getcontext functionality. 4 years ago
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src 5f354cb7b9 mips/tilegx: Add missing unwind_i.h header file 4 years ago
tests 544cdb3b43 tests/Gtest-trace.c: show differing addresses 6 years ago
.gitignore 5b55e556ca test-resume-sig-rt: test unw_resume() in presence of "realtime" signal frame 8 years ago
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LICENSE 63a6a95489 Delete obsolete BitKeeper files, add LICENSE file. 14 years ago 6e3254ea6e [PATCH] Fix build from scratch 6 years ago
NEWS d7322f0f64 Update to v1.1 8 years ago
README b2db825e8a Update README to use 5 years ago
TODO bc22c6ecf2 Update. 16 years ago
acinclude.m4 9ef9445558 Don't check for atomic_ops library for now. 16 years ago 6e3254ea6e [PATCH] Fix build from scratch 6 years ago a77b0cd7bd Bump version to v1.2.1 3 years ago


-*- mode: Outline -*-

This is version 1.0 of the unwind library. This library supports
several architecture/operating-system combinations:

Linux/x86-64: Works well.
Linux/x86: Works well.
Linux/ARM: Works well.
Linux/IA-64: Fully tested and supported.
Linux/PARISC: Works well, but C library missing unwind-info.
HP-UX/IA-64: Mostly works but known to have some serious limitations.
Linux/AArch64: Newly added.
Linux/PPC64: Newly added.
Linux/SuperH: Newly added.
FreeBSD/i386: Newly added.
FreeBSD/x86-64: Newly added (FreeBSD architecture is known as amd64).
Linux/Tilegx: Newly added (64-bit mode only).

* General Build Instructions

In general, this library can be built and installed with the following

$ ./ # Needed only for building from git. Depends on libtool.
$ ./configure
$ make
$ make install prefix=PREFIX

where PREFIX is the installation prefix. By default, a prefix of
/usr/local is used, such that libunwind.a is installed in
/usr/local/lib and unwind.h is installed in /usr/local/include. For
testing, you may want to use a prefix of /usr/local instead.

* Building with Intel compiler

** Version 8 and later

Starting with version 8, the preferred name for the IA-64 Intel
compiler is "icc" (same name as on x86). Thus, the configure-line
should look like this:

$ ./configure CC=icc CFLAGS="-g -O3 -ip" CXX=icc CCAS=gcc CCASFLAGS=-g \

* Building on HP-UX

For the time being, libunwind must be built with GCC on HP-UX.

libunwind should be configured and installed on HP-UX like this:

$ ./configure CFLAGS="-g -O2 -mlp64" CXXFLAGS="-g -O2 -mlp64"

Caveat: Unwinding of 32-bit (ILP32) binaries is not supported
at the moment.

** Workaround for older versions of GCC

GCC v3.0 and GCC v3.2 ship with a bad version of sys/types.h. The
workaround is to issue the following commands before running

$ mkdir $top_dir/include/sys
$ cp /usr/include/sys/types.h $top_dir/include/sys

GCC v3.3.2 or later have been fixed and do not require this

* Building for PowerPC64 / Linux

For building for power64 you should use:

$ ./configure CFLAGS="-g -O2 -m64" CXXFLAGS="-g -O2 -m64"

If your power support altivec registers:
$ ./configure CFLAGS="-g -O2 -m64 -maltivec" CXXFLAGS="-g -O2 -m64 -maltivec"

To check if your processor has support for vector registers (altivec):
cat /proc/cpuinfo | grep altivec
and should have something like this:
cpu : PPC970, altivec supported

If libunwind seems to not work (backtracing failing), try to compile
it with -O0, without optimizations. There are some compiler problems
depending on the version of your gcc.

* Building on FreeBSD

General building instructions apply. To build and execute several tests,
you need libexecinfo library available in ports as devel/libexecinfo.

Development of the port was done of FreeBSD 8.0-STABLE. The library
was build with the system compiler that is modified version of gcc 4.2.1,
as well as the gcc 4.4.3.

* Regression Testing

After building the library, you can run a set of regression tests with:

$ make check

** Expected results on IA-64 Linux

Unless you have a very recent C library and compiler installed, it is
currently expected to have the following tests fail on IA-64 Linux:

Gtest-init (should pass starting with glibc-2.3.x/gcc-3.4)
Ltest-init (should pass starting with glibc-2.3.x/gcc-3.4)
test-ptrace (should pass starting with glibc-2.3.x/gcc-3.4)
run-ia64-test-dyn1 (should pass starting with glibc-2.3.x)

This does not mean that libunwind cannot be used with older compilers
or C libraries, it just means that for certain corner cases, unwinding
will fail. Since they're corner cases, it is not likely for
applications to trigger them.

Note: If you get lots of errors in Gia64-test-nat and Lia64-test-nat, it's
almost certainly a sign of an old assembler. The GNU assembler used
to encode previous-stack-pointer-relative offsets incorrectly.
This bug was fixed on 21-Sep-2004 so any later assembler will be

** Expected results on x86 Linux

The following tests are expected to fail on x86 Linux:

Gtest-resume-sig (fails to get SIGUSR2)
Ltest-resume-sig (likewise)
Gtest-dyn1 (no dynamic unwind info support yet)
Ltest-dyn1 (no dynamic unwind info support yet)
test-setjmp (longjmp() not implemented yet)
run-check-namespace (no _Ux86_getcontext yet)

** Expected results on x86-64 Linux

The following tests are expected to fail on x86-64 Linux:

Gtest-dyn1 (no dynamic unwind info support yet)
Ltest-dyn1 (no dynamic unwind info support yet)
Gtest-init (see
Ltest-init (likewise)
test-async-sig (crashes due to bad unwind-info?)
test-setjmp (longjmp() not implemented yet)
run-check-namespace (no _Ux86_64_getcontext yet)
run-ptrace-mapper (??? investigate)
run-ptrace-misc (see

** Expected results on PARISC Linux

Caveat: GCC v3.4 or newer is needed on PA-RISC Linux. Earlier
versions of the compiler failed to generate the exception-handling
program header (GNU_EH_FRAME) needed for unwinding.

The following tests are expected to fail on x86-64 Linux:

Gtest-bt (backtrace truncated at kill() due to lack of unwind-info)
Ltest-bt (likewise)
Gtest-resume-sig (Gresume.c:my_rt_sigreturn() is wrong somehow)
Ltest-resume-sig (likewise)
Gtest-init (likewise)
Ltest-init (likewise)
Gtest-dyn1 (no dynamic unwind info support yet)
Ltest-dyn1 (no dynamic unwind info support yet)
test-setjmp (longjmp() not implemented yet)
run-check-namespace (toolchain doesn't support HIDDEN yet)

** Expected results on HP-UX

"make check" is currently unsupported for HP-UX. You can try to run
it, but most tests will fail (and some may fail to terminate). The
only test programs that are known to work at this time are:


** Expected results on PPC64 Linux

"make check" should run with no more than 10 out of 24 tests failed.

* Performance Testing

This distribution includes a few simple performance tests which give
some idea of the basic cost of various libunwind operations. After
building the library, you can run these tests with the following

$ cd tests
$ make perf

* Contacting the Developers

Please direct all questions regarding this library to:

You can do this by sending a mail to with
a body of:

subscribe libunwind-devel

or you can subscribe and manage your subscription via the
web-interface at: