[Qemu-devel] gpu and console chicken and egg

[Dave Airlie]

So I've hit a bit of a init ordering issue that I'm not sure how best to solve,

Just some background:
In order for the virt GPU and the UI layer (SDL or GTK etc) to
interact properly over OpenGL use, I have created and OpenGL provider
in the console, and the UI layer can register callbacks for a single
GL provider (only one makes sense really) when it starts up. This is
mainly to be used for context management and swap buffers management.

Now in the virtio GPU I'd was going to use a virtio feature to say
whether the qemu hw can support the 3D renderer, dependant on whether
it was linked with the virgl renderer and whether the current UI was
GL capable.

I also have the virtio gpu code checking in its update_display
callback whether the first console has acquired a GL backend.

Now the problem:
The virtio hw is initialised before the console layers. So the feature
bits are all set at that point, before the UI ever registers a GL
interface layer. So is there a method to modify the advertised feature
bits later in the setup sequence before the guest is started? Can I
call something from the update display callback?

Otherwise I was thinking I would need something in my config space on
top of feature bits to say the hw is actually 3d capable.

Dave.