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From: Rob Landley <rob@landley.net>
Subject: Re: [Qemu-devel] [PATCH] qemu-i386 segfaults running "hello world".
Date: Sun, 24 Jun 2007 03:36:36 -0400
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To: qemu-devel@nongnu.org

On Saturday 23 June 2007 07:12:39 Stefan Weil wrote:
> Rob Landley schrieb:
> > Ok, it's a more fundamental problem:
> >
> > landley@triolith:/sys$ qemu-i386
> > Segmentation fault (core dumped)
> >
> > Nothing to do with the program it's trying to run, it segfaults with no
> > arguments.
> >
> > Is anybody else seeing this?
> >
> > Rob
>
> Yes, I see this on Debian Linux since several months (libc update?).

Ubuntu 7.04 is using glibc-2.5.

> The crash is caused by libc startup code which calls a null pointer.
> QEMU provides this null pointer with the __init_array_start
> workaround in linux-user/main.c.

What exactly is this working around, anyway?  There are comments in the code 
that it's doing something fancy (being both a shared library and an 
executable, I think) but I'm not sure why...

> This can be fixed with some kind of code hack - see my patch
> (which is not really a solution, but one more workaround).

I applied your patch and still got the segfault.

> Nevertheless user mode emulations remains unusable even
> with this patch because of TLS problems.

That I know how to work around.  Set the environment variable 
LD_ASSUME_KERNEL=2.4.1 and glibc won't try to use TLS.

> Regards,
> Stefan

Rob

-- 
"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.