Re: [Xen-devel] xenstored crashes with SIGSEGV

[Philipp Hahn <hahn@xxxxxxxxxxxxx>]

Hello Ian,

On 18.12.2014 11:17, Ian Campbell wrote:
> On Tue, 2014-12-16 at 16:13 +0000, Frediano Ziglio wrote:
>> Do we have a bug in Xen that affect SSE instructions (possibly already
>> fixed after Philipp version) ?
> 
> I've had a niggling feeling of Deja Vu over this which I'd been putting
> down to an old Xen on ARM bug in the area of FPU register switching.
> 
> But it seems at some point (possibly even still) there was a similar
> issue with pvops kernels on x86, see:
>         http://bugs.xenproject.org/xen/bug/40

That definitely looks interesting.

> Philipp, what kernel are you guys using?

The crash "2014-12-06 01:26:21 xenstored[4337]" happened on linux-3.10.46.

That kernel is missing v3.10.50-13-gd1cc001:
> commit d1cc001905146d58c17ac8452eb96f226767819d
> Author: Silesh C V <svellattu@xxxxxxxxxx>
> Date:   Wed Jul 23 13:59:59 2014 -0700
>
>     coredump: fix the setting of PF_DUMPCORE
>     commit aed8adb7688d5744cb484226820163af31d2499a upstream.
which explains why the xmm* registers are not included in the core file.

> I also can't quite shake the feeling that there was another much older
> issue relating to FPU context switch on x86, but I think that was truly
> ancient history (2.6.18 era stuff)

Some of those host might still use 3.2, most use 3.10.x, but definitely
no 2.6 kernels.

Xen-Hypervisor is 4.1.3

If you need anything more, just ask. It might take me some time to
answer as I'm on vacation for the next 2 weeks.

Thanks again for your help.
Philipp

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