Re: [GIT PULL] x86 fixes

Ingo Molnar
2015-08-18T07:55:25Z

* 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