"Michael S. Tsirkin" [off-list ref] writes:

On Tue, Jan 13, 2015 at 04:43:07PM +0200, Michael S. Tsirkin wrote:

quoted

virtio 1.0 says device configuration is optional, but most drivers treat it as
mandatory.  Even if presented by device, guest bios might disable the BAR
holding that configuration, so we can't assume it's there, but we also don't
want to fail if not in case drivers can cope with it's absence - such as caif
or rng.

Add code to drivers to check presence of get callback and fail gracefully.

Rusty, in case it's not clear: I'd like to hear
your opinion on these patches, since virtio pci modern
driver I'm now preparing for submission, depends on this.

Just to note for anyone following, that these are now in my virtio-next
tree.

Cheers,
Rusty.