RE: [Xen-users] graphic card on domU

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: Abe [mailto:lynchbay@xxxxxxxxx] 
> Sent: 15 March 2007 11:15
> To: Petersson, Mats
> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] graphic card on domU
> 
> On 3/15/07, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> > >
> > > I actually removed the graphic card driver from domain0... and I
> > > removed X as well
> > > what about the PS2?
> >
> > The graphics driver -> the "drm" for X, right? There's also 
> the VGA/FB
> > driver which grabs the graphics card VERY early on in the 
> boot. And Xen
> > itself likes to hold on to the VGA card for console 
> messages. I'm not
> > sure if you can actually get rid of those at all.
> 
> so maybe it is a question for xen-devel after all :P
Why?

> what exactly do you mean by "drm"?

"Direct Rendering Module" - the X-windows kernel modules to support
differnet graphics cards using "DRI" (Direct Rendering Infrastructure". 

> I am not in concern for the *VGA* state, it can easily be reset.

Yes, but if you're working in graphics mode (X) and the Dom0 decides to
write to the VGA controller, your graphics card may not "appreciate" it.
Since there's no direct communication between the DomU and Dom0 about
what's going on in the different "world", the context of the graphics
card may be severely damaged by performing VGA writes to a graphics
context (or the other way around). 

So you need Dom0 to "give up" it's VGA ownership if you want DomU to
access the graphics card. And that's not going to be easy. The only
(easy) solution is to have two graphics cards and giving the SECOND one
to DomU. 

This is not the first time this question has been asked...

--
Mats
> 
> thanks,
> Abe
> 
> 
> 



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