Re: [Qemu-devel] [RFC] virtio-mmio: implement modern (v2) personality (virtio-1)

[Laszlo Ersek]

On 07/29/19 14:57, Sergio Lopez wrote:
> Implement the modern (v2) personality, according to the VirtIO 1.0
> specification.
> 
> Support for v2 among guests is not as widespread as it'd be
> desirable. While the Linux driver has had it for a while, support is
> missing, at least, from Tianocore EDK II, NetBSD and FreeBSD.

That's right; not only are there no plans to implement virtio-mmio/1.0
for OVMF (to my knowledge), I'd even argue against such efforts.

OVMF is a heavy-weight guest firmware, which I see entirely out of scope
for "micro VMs". And so virtio-mmio/1.0 would seem like a needless &
unwelcome complication, from the OVMF maintainership perspective.

(This should not be construed as an argument against "micro VMs" -- I
always say, identify your use case, then pick the right components for
it. I never try to convince people to use OVMF indiscriminately.)

> For this reason, the v2 personality is disabled, keeping the legacy
> behavior as default. Machine types willing to use v2, can enable it
> using MachineClass's compat_props.

This approach makes me happy (with the understanding that edk2 guest
firmware is not going to target the new machine type(s) in question).

Thanks!
Laszlo