Hi,> I don't know. This seems exactly like the kind of thing > we had in mind when we added the virtio pci capability. > For example, we have text in spec that requires drivers > to skip unknown capabilities. > > And yes, if bios pokes at a specific bar then we do > need to list this info in the virtio spec so this makes > it an issue that is virtio related.Hmm, virtio-vga is a two-in-one device basically. When virtio is enabled it behaves like virtio-gpu-pci, otherwise it behaves very simliar to stdvga. So you need to know nothing about virtio to handle the vga side, and I want keep it that way. When no vga compatibility is needed there always is the option to just use virtio-gpu-pci instead.> Yes, it's not about what we put there now. It's about being able > to move things about in the future without breaking guests.We don't have that today for stdvga, and I still fail to see what this buys us. Completely different thing crossing my mind: I think we can make virtio-vga fully compatible with stdvga. stdvga has two bars, memory (#0) and mmio (#2). We can make the mmio bar larger and place all the virtio regions there. I think in any case I'll go split off the vga compatibility bits to a different patch (and possible a separate patch series). cheers, Gerd
On Thu, Mar 26, 2015 at 04:07:16PM +0100, Gerd Hoffmann wrote:> Hi, > > > I don't know. This seems exactly like the kind of thing > > we had in mind when we added the virtio pci capability. > > For example, we have text in spec that requires drivers > > to skip unknown capabilities. > > > > And yes, if bios pokes at a specific bar then we do > > need to list this info in the virtio spec so this makes > > it an issue that is virtio related. > > Hmm, virtio-vga is a two-in-one device basically. When virtio is > enabled it behaves like virtio-gpu-pci, otherwise it behaves very > simliar to stdvga. So you need to know nothing about virtio to handle > the vga side, and I want keep it that way. > > When no vga compatibility is needed there always is the option to just > use virtio-gpu-pci instead. > > > Yes, it's not about what we put there now. It's about being able > > to move things about in the future without breaking guests. > > We don't have that today for stdvga, and I still fail to see what this > buys us. > > > Completely different thing crossing my mind: I think we can make > virtio-vga fully compatible with stdvga. stdvga has two bars, memory > (#0) and mmio (#2). We can make the mmio bar larger and place all the > virtio regions there. >Full compatibility with some standard sounds like a better motivation, yes.> > I think in any case I'll go split off the vga compatibility bits to a > different patch (and possible a separate patch series). > > cheers, > GerdWill you still need me to change core to claim specific memory only? -- MST
Hi,> > > > Completely different thing crossing my mind: I think we can make > > virtio-vga fully compatible with stdvga. stdvga has two bars, memory > > (#0) and mmio (#2). We can make the mmio bar larger and place all the > > virtio regions there. > > > > Full compatibility with some standard sounds like a better motivation, > yes.Ok, I'll look into it.> > I think in any case I'll go split off the vga compatibility bits to a > > different patch (and possible a separate patch series). > > > > cheers, > > Gerd > > Will you still need me to change core to claim specific memory only?That would be great, yes. The resource conflict with vesafb/efifb will stay no matter how we design the pci resource layout of virtio-vga. cheers, Gerd