[Qemu-devel] Re: [PATCH 0/2] fix virtio_blk serial pci config breakage

[Anthony Liguori]

Michael S. Tsirkin wrote:
> I don't think it's such a good idea.  We want to keep exposing most of
> config space in i/o bar because of backwards compatibility.  And we want
> to keep datapath operations such as vq kicks, in i/o space.
>   

We can do feature negotiation in virtio-pci.  That lets us continue 
exposing the first 246 bytes of the config space in PIO and guests can 
negotiate a second bar for access to larger config spaces.

Regards,

Anthony Liguori