[SeaBIOS] [PATCH] virtio: add struct vp_device

[Gerd Hoffmann]

  Hi,

> You could use the config capability if you wanted
> to, though that multiplies the cost of each access
> by a factor of ~4.

We are moving to 32bit drivers _anyway_, some of our drivers run in
32bit mode already, and with SMM mode landing in kvm now we have a
reliable way to transition to 32bit mode and back, even in corner cases
like guest calling bios from vm86 mode.

So, I don't feel like using the config capability.  Might be useful for
virtio-net driver in ipxe though, didn't look there yet.

> I noticed that QEMU doesn't support it but it must, I'll fix it up now.

I've also noticed we are back to 8M pci bars for modern/transitional
virtio devices, due to supporting up to 1024 virt queues now I think.

Should we introduce a per-device virt queue limit?  Supporting 1024
queues makes sense for virtio-scsi, virtio-net and maybe virtio-serial.
Other devices will never ever come even close to 1024 virt queues ...

cheers,
  Gerd