serious(?) glibc backtrace() problem on IA64

[Andrew Haley]

Boehm, Hans writes:
 > Gcc 3.1 libjava seems to invoke the glibc backtrace() function
 > Throwable::fillInStackTrace whenever it appears to be available.
 > Unfortunately, at least my copy of glibc 2.2.4 seems to use the
 > sysdeps/generic implementation of backtrace() on IA64.  That
 > implementation in fact completely broken on IA64.  The end result
 > seems to be that mostly it quietly does nothing useful,
 > occasionally it generates an unaligned access, and even less
 > frequently it generates a SIGSEGV.

Right.  The libjava backtrace has been broken since the new gcc
unwinder went in.

 > Is this fixed in other versions of glibc?  Should the libjava configury
 > stuff explicitly turn off HAVE_BACKTRACE? 

That sounds right.

 > If so, can an autoconf expert add that hack to at least the 3.1
 > tree?

 > In the longer term, if this is still in glibc, it seems to me that this is
 > the wrong default for backtrace() on IA64.

I would prefer to use libunwind, to begin with for IA-64, and later
for everything.

Andrew.