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Re: [Xen-devel] Bug in x86 instruction emulator?

On Wed, 6 Apr 2016 02:57:35 +0300 Mihai Donțu wrote:
> On Wed, 06 Apr 2016 01:38:32 +0200 wogiz@xxxxxxxxxxxxxxx wrote:
> > I'm running Xen 4.6.1 with Alpine Linux 3.3.3 in dom0. In a HVM domU 
> > with vga="qxl", Xorg will segfault instantly if tried started. Multiple 
> > Linux distros have been tested and Xorg segfaults in all.
> > 
> > Attached are a full backtrace from domU generated by Xorg, and a 
> > assembler dump of function 'sse2_blt'.
> > 
> > According to Xen IRC channel, the cause could be a bug in the x86 
> > instruction emulator related to SSE.  
> I don't believe the x86 emulator is complete wrt the SSE instruction
> set. But I do wonder why, in your case, these instructions need
> emulation at all. Unless touching the video RAM requires emulation. Can
> you try using a different video driver? I see xorg picked up qxl, maybe
> try vesa?

This would appear to be an old issue with qxl and xen:

Mihai Donțu

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