README

-*- mode: Outline -*-

This is version 0.97 of the unwind library.  At the moment, only the
IA-64 Linux (IPF Linux) platform is fully supported.  Some basic
support for x86 and HP-UX/IPF exists also.  However, the x86 support
is based mostly on the frame-chain and does not reliably use unwind
information yet, so its utility is limited.  Similarly, the HP-UX/IPF
support is incomplete, though it is sufficient to do a basic
backtrace.  unw_resume() is not supported, however.

* Important GCC v3.4.0 Caveat

GCC v3.4.0 breaks C++ ABI compatibility and because of that, libunwind
cannot easily be used as the unwinder for GCC v3.4.0.  The GCC
developers are aware of the problem [1] and the expectation is that
the problem will be fixed with GCC v3.4.1.  In the meantime, it may be
best to avoid using GCC v3.4.0.

[1] http://gcc.gnu.org/ml/gcc/2004-04/msg00989.html

* General Build Instructions

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

	$ ./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

** Up to version 7

To build libunwind with the Intel Electron compiler (ECC), it is
recommended to run configure like this:

	$ ./configure CC=ecc CXX=ecc CCAS=gcc CCASFLAGS=-g \
		LDFLAGS="-L$PWD/src/.libs"

The reason for this is that ECC uses the Intel assembler, which
doesn't grok some of the IA-64 assembly code in the "tests" directory.

For an ECC-built version of libunwind to work properly, you also need
to ensure that /usr/include/asm/fpu.h contains a "long double" member
called "__dummy" in the declaration of "struct ia64_fpreg".  Without
that member, variables of type unw_context_t won't be aligned
properly.

** 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 \
		LDFLAGS="-L$PWD/src/.libs"


* Building on HP-UX

For the time being, libunwind must be built with GCC on HP-UX.
Unfortunately, gcc-3.0 and gcc-3.2 ship with a bad version of
sys/types.h.  The workaround for this is:

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

Apart from this glitch, libunwind should configure and install on
HP-UX like this:

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

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

* 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.

** Expected results on x86 Linux

The following tests are expected to fail on x86 Linux:

	test-proc-info		(x86 unwinder doesn't use unwind-info yet)
	Gtest-exc		(unw_resume() not implmented yet)
	Ltest-exc		(unw_resume() not implmented yet)
	test-setjmp		(unw_resume() not implmented yet)

** Expected results on HP-UX

"make check" is currently unsupported for HP-UX.  The only test
programs that are known to work at this time are tests/bt (which
produces various backtraces) and tests/Gperf-simple, which does some
simple performance measurements.

* 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
commands:

 $ cd tests
 $ make perf

* Contacting the Developers

Please direct all questions regarding this library to:

	libunwind@linux.hpl.hp.com

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