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

[Weidong Han <weidong.han@xxxxxxxxx>]

Pasi Kärkkäinen wrote:
> On Thu, Jan 21, 2010 at 05:52:15PM +0800, Weidong Han wrote:
>   
> > 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.
> >     
> So at this point should be add two things:
>
> 1) option in guest cfgfile telling from which card to copy the vbios from
>   
I think adding an option in guest config file to indicate primary or 
secondary gfx assignment can cover this.
> 2) option to load the vbios from a file specified in guest cfgfile
>   
I don't prefer this. It involves much manual work for users. It's better 
to find a general solution which is also easy to use.
Regards,
Weidong

> How does that sound like? 
>
> -- Pasi
>
>   

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