README

-*- mode: Outline -*-

This is version 0.92 of the unwind library.  At the moment, only the
IA-64 Linux (IPF Linux) platform is fully supported.  Some very basic
support for x86 exists also.  However, the x86 support is based purely
on the frame-chain and does not use unwind information, so its utility
is limited.

* 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.

If, during the build, you're getting an error of the form:

  ../src/.libs/libunwind-ia64.so: undefined reference to `__tls_get_addr'

it indicates that you have a compiler which supports the `__thread'
keyword, but a runtime system (C library), which does not.  As of
September 2003, this appears to be a common problem for Debian
"unstable" systems.  To work around this issue, run "./configure" with
option "--disable-__thread".


* Building with Intel ECC

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

	$ ./configure CC=ecc CXX=ecc CCAS=gcc

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.

* Building on HP-UX

For the time being, libunwind must be built with GCC on HP-UX.
Unfortunately, gcc-3.0 ships 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

* Regression Testing

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

	$ make check

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

	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.

* Contacting the Developers

Please direct all questions regarding this library to:

	libunwind@linux.hpl.hp.com

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