Re: [Qemu-devel] [PATCH RFC 03/11] virtio: support more feature bits

[Cornelia Huck]

On Mon, 13 Oct 2014 16:23:58 +1030
Rusty Russell <address@hidden> wrote:

> Cornelia Huck <address@hidden> writes:
> > With virtio-1, we support more than 32 feature bits. Let's make
> > vdev->guest_features depend on the number of supported feature bits,
> > allowing us to grow the feature bits automatically.
> 
> It's a judgement call, but I would say that simply using uint64_t
> will be sufficient for quite a while.

I prefer this as an array for two reasons:

- It matches what ccw does anyway (we read/write features in chunks of
  32 bit), so this makes the backend handling for this transport very
  straightforward.
- While I don't see us running out of 64 feature bits for a while, we'd
  have to touch every device and transport again when we do. I'd prefer
  to do this once, as we need to change code anyway.