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Date: Tue, 18 Aug 2015 09:55:20 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Juergen Gross <jgross@suse.com>, Andy Lutomirski <luto@kernel.org>,
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        Brian Gerst <brgerst@gmail.com>, Denys Vlasenko <dvlasenk@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] x86 fixes
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* Andy Lutomirski <luto@amacapital.net> wrote:

> On Mon, Aug 17, 2015 at 1:01 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> > So when I re-introduced static allocations math-emu started working again, to 
> > a limited degree: on a modern distro, trying to boot /bin/bash I got a prompt, 
> > but various programs would segfault. I did not investigate it any deeper, I 
> > suppose the FPU emulation does not go far enough for modern user-space, or 
> > maybe it has more bugs.
> 
> Were you testing with just no387 or did you run a VM with SSE2 and such turned 
> off?
> 
> There's a *lot* of userspace that incorrectly checks for instructions without 
> checking for the state support.  I've filed bugs against libgcc for this and 
> they're still not fixed IIRC.

I tested relatively ancient user-space, 2007 era Fedora Core 6 - but I didn't 
check whether it's truly SSE-less (it probably isn't).

Thanks,

	Ingo