Bug#634261: Debian #634261: Is it actually a(n RC) bug?

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi,

I am not really an expert on libc internals, but a friend of mine with
some more experience did some debugging yesterday and we figured out
it might not be a bug but expected behavior. I'll put my points by
answering some of the above statements.

> FYI, I found that it is triggered by the _IO_stdin_used symbol not
> being exported from the binary, which happened because of a version-script
> couple with -rdynamic. I still think there is something fishy going on
> on the libc6 side, but not as bad as originally thought.

This seems to be a known and more or less documented behavior of libc
to determine which ABI to use for an application software, see [1].

What eventually happens is an unaligned access due to the ABI
mismatch.

Checking the export list of the current xulrunner binary of Iceweasel
10, this behaviour seems to have been fixed in Firefox. So I expect
Firefox to work on SPARC again.

> What is fishy is that only sparc is affected. So whatever it's doing
> on sparc, it's doing it differently from other architectures.

That's because SPARC CPUs trigger an exception on aligned access
[1]. I would expect the same to happen on Alpha [3], but Alpha is no
longer a supported architecture for the current Debian release.

It would be nice if the original bug reporter could try to reproduce
the bug with Iceweasel 10 in Debian Wheezy and unless it's still
crashing, this bug should be untagged as being an RC bug for Wheezy.

Cheers,

Adrian

> [1] http://lists.gnu.org/archive/html/bug-glibc/2001-12/msg00203.html
> [2] http://gcc.gnu.org/ml/gcc/2000-10/msg00291.html
> [3] http://gcc.gnu.org/ml/gcc-help/1999-10n/msg00065.html

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
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