Re: [Xen-devel] Xen 4.0.0 first release candidate / graphics passthru

[Weidong Han <weidong.han@xxxxxxxxx>]

Jean Guyader wrote:
> 2010/1/21 Pasi Kärkkäinen <pasik@xxxxxx>:
>   
> > On Thu, Jan 21, 2010 at 09:09:35AM +0000, Jean Guyader wrote:
> >     
> > > 2010/1/21 Pasi Kärkkäinen <pasik@xxxxxx>:
> > >       
> > > > On Tue, Jan 12, 2010 at 10:05:12AM +0000, Keir Fraser wrote:
> > > >         
> > > > > On 12/01/2010 09:32, "Pasi Kärkkäinen" <pasik@xxxxxx> wrote:
> > > > >
> > > > >           
> > > > > > > > Does 4.0 include gpu passthru features? If not are there any updated
> > > > > > > > patches to try gpu passthru with 4.x?
> > > > > > > >                 
> > > > > > > There is support (c/s 20144).
> > > > > > >
> > > > > > >               
> > > > > > Btw is it possible now to specify a file to load the VGA bios from?
> > > > > > earlier it was required to hardcode it into some header file or so.
> > > > > >             
> > > > > I think it is hardcoded that qemu will take a copy of the host system's BIOS
> > > > > (i.e., for the primary host VGA). Other options would be easy to implement
> > > > > I'm sure, if someone's interested.
> > > > >
> > > > >           
> > > > I was just looking at same older mails, and it seems for example Teo En Ming
> > > > and others who got Xen VGA passthrough working had to copy the vgabios-pt.bin
> > > > to tools/firmware/vgabios/ before building Xen.
> > > >
> > > > That's not very practical..
> > > >
> > > >         
> > > Right now the code copy the bios from 0xC0000. So if you want to pass through
> > > a secondary display adapter with the vga bios you are not copying the right one,
> > > that why this hack was for.
> > > Surely the code could be modified to add an option to copy the bios of
> > > the right card.
> > >
> > >       
> > Ok, thanks for the info.
> >
> > Do I remember correctly that there was a problem with copying the BIOS from 
> > some cards,
> > or on some setups? And that's why the patch to load it from a file was made?
> >
> >     
> Yes, I think that was because of that, and I'm not sure about the
> intel IGD but I think that was causing some issue.
> The code could have a cleanup and use sysfs to get the rombios, if I
> works with the intel graphic card I think we should do that.
>
> Jean
>   
vbios copied from 0xC0000 doesn't work for some graphics cards, e.g. 
Nvidia GS 8400, due to the vbios code is modified after initialization. 
So it needs to load it from file. yes, it's not practical, Intel IGD 
cards don't have this issue in our tests.  One possible good solution is 
to load vbios from expansion ROM of graphics cards, but we found 
expansion ROM address are invalid for some graphics cards, even using 
Linux upstream.  It needs to look into Linux code.
Regards,
Weidong


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