linux-kernel - Re: [GIT PULL] x86 fixes

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Message-ID: <CALCETrUFpqb8=dYq0q4JomaH1i51OrY48B6PKZQbaN2mOxMW+w@mail.gmail.com>
Date:	Mon, 17 Aug 2015 16:59:18 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Juergen Gross <jgross@...e.com>,
	Andy Lutomirski <luto@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] x86 fixes

On Mon, Aug 17, 2015 at 1:01 AM, Ingo Molnar <mingo@...nel.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.

--Andy
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