On 07.04.25 10:49, Michael S. Tsirkin wrote:
On Mon, Apr 07, 2025 at 10:44:21AM +0200, David Hildenbrand wrote:
Whoever adds new feat_X *must be aware* about all previous features, otherwise we'd be reusing feature bits and everything falls to pieces.
The knowledge is supposed be limited to which feature bit to use.
I think we also have to know which virtqueue bits can be used, right?
what are virtqueue bits? vq number?
Yes, sorry.
Assume cross-vm as an example. It would make use of virtqueue indexes 5+6 with their VIRTIO_BALLOON_F_WS_REPORTING.
So whatever feature another device implements couldn't use this feature bit or these virtqueue indexes.
(as long the other device never intends to implement VIRTIO_BALLOON_F_WS_REPORTING, the virtqueue indexes could be reused. But the spec will also be a mess, because virtqueue indexes could also have duplicate meanings ... ugh)