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[libvirt] qemu qxl video memory parameter - windows bsod with spice



Hi,

Please see the below discussion with the spice community. 

libvirt is adding a parameter about video ram to qemu process and this parameter might be responsible of a crash in the qxl at higher resolutions. Spice people tell me that their default ram should be 64 Mbytes. 

I'm using libvirt 0.9.0 and qemu 0.14,  virt-manager 0.8.7. When configuring a guest in virt-manager, cirrus driver is added as default, then you can change it to qxl, but the 9 MB videoram parameter can't be adjusted and it does not automatically change to 64 MB. If you add a 2nd qxl video card, then it has 64 MB memory.

The parameter that qemu gets with one qxl device is:

     -vga qxl -global qxl-vga.vram_size=9437184

The parameter that qemu gets with a second qxl device is:

     -vga qxl -global qxl-vga.vram_size=9437184 -device qxl,id=video1,vram_size=67108864,bus=pci.0,addr=0x8

Is this a bug in libvirt or other related tools?

Thanks,
Br,
Emre

---------- Forwarded message ----------
From: Emre Erenoglu <erenoglu gmail com>
Date: Wed, May 4, 2011 at 7:42 PM
Subject: Re: [Spice-devel] windows bsod with spice 0.8.1
To: Emre Erenoglu <erenoglu gmail com>, spice-devel freedesktop org


On Wed, May 4, 2011 at 6:00 PM, Alon Levy <alevy redhat com> wrote:
On Wed, May 04, 2011 at 05:10:31PM +0400, Emre Erenoglu wrote:
> On Wed, May 4, 2011 at 2:12 PM, Alon Levy <alevy redhat com> wrote:
>
> > On Wed, May 04, 2011 at 01:45:39PM +0400, Emre Erenoglu wrote:
> > > On Wed, Apr 27, 2011 at 1:16 AM, Emre Erenoglu <erenoglu gmail com>
> > wrote:
> > >
> > > > Hi,
> > > >
> > > > I started to see frequent crashes with my guests running windows xp and
> > > > windows server 2003 x86.  The bsod appears on qxldd.dll. I can give
> > further
> > > > info if needed.
> > > >
> > > > The host is Linux x86_64, qemu 0.14, spice 0.8.1. Guest has qxl 0.6.1
> > > > drivers loaded. I may revert back to 0.8.0 since it was not crashing.
> > > > Nothing changed in the guests when I upgraded spice from 0.8.0 to
> > 0.8.1.
> > > >
> > > >
> > > Some updates on the original issue. I checked a lot and I found out that
> > the
> > > issue continued with any version of spice and guest qxl drivers.
> > >
> > > I finally digged down to the point that, the qemu comment line which
> > states
> > > "   -global qxl-vga.vram_size=9xxxxxx  " parameter is the problem. When
> > the
> > > guest is started with 9 MB of video memory given as comment line
> > parameter
> > > to qemu, the guest qxldd driver crashes with BSOD.
> >
> > Why was it started with 9MB? anyway, good catch, we should add a check for
> > this
> > in the driver (and probably just refuse to load). Could you open a bug on
> > this
> > in bugzilla.freedesktop.org?
> >
>
> This is added by libvirt (virt-manager) when launching qemu. Do we need to
> file it against libvirt or against spice?  I will post this to the libvirt
> list also.
>
> Btw, rather than refusing to load, I think we should just limit the possible
> resolutions. I'm not sure if the resolutions are the issue though. The crash
> was not happening immediately and it was working OK with that 9 MB memory.
> When I launched outlook, or IE8, or just in the middle of an application, it
> could crash and bsod.

But that number doesn't make any sense - the spice default is 64MB, we never tested
with less then that. It is probably fixable like you say, but until that's fixed why
not stick to the spice default?

Well, this parameter is not configurable from the virt-manager UI and it configures 9 MB to the command line of qemu by libvirt (even latest 0.9.0) version. 
When you add a 2nd VGA adapter, it adds 64 MB to that adapter correctly (-device qxl,id=video1,vram_size=67108864,bus=pci.0,addr=0x8)

I guess i need to file a bug report to libvirt too.

Emre

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