# Re: \[PATCH\] Add virtio gpu driver.

- From: Gerd Hoffmann \<kraxel@redhat.com\>
- Date: 2015-03-26 07:12:56 
- List: linux-api
- Page: https://ratatoskr.run/linux-api/2015/03/4459645
- Thread: https://ratatoskr.run/dri-devel/2015/03/4458206/t.md

```text
On Mi, 2015-03-25 at 18:09 +0100, Michael S. Tsirkin wrote:
> On Wed, Mar 25, 2015 at 04:37:16PM +0100, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > BTW can we teach virtio-gpu to look for framebuffer using
> > > virtio pci caps?
> > 
> > The virtio-gpu driver doesn't matter much here, it doesn't use it
> > anyway.
> > 
> > >  Or are there limitations such as only
> > > using IO port BARs, or compatibility with
> > > BIOS code etc that limit us to specific BARs anyway?
> > 
> > Yes, vgabios code needs to know.  Currently it has bar #2 for the vga
> > framebuffer bar hardcoded.  It's 16bit code.  I don't feel like making
> > the probing more complicated ...
> > 
> > cheers,
> >   Gerd
> 
> OK - you are saying all VGA cards use bar #2 for this
> functionality, so we are just following
> established practice here?

vgabios checks pci ids to figure.  qxl+stdvga use bar #0, vmware-vga bar
#1, virtio-vga bar #2.

cheers,
  Gerd


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