On Tue, May 16, 2023 at 07:11:36PM +0000, Parav Pandit wrote: > > > From: Michael S. Tsirkin <m...@redhat.com> > > Sent: Tuesday, May 16, 2023 2:22 AM > > > > On Mon, May 15, 2023 at 03:59:41PM +0000, Parav Pandit wrote: > > > > > > > From: Jason Wang <jasow...@redhat.com> > > > > Sent: Monday, May 15, 2023 3:31 AM > > > > > > > > What do we gain from bisecting it? > > > > > > > > > > > > 1) No need to deal with the offset in the hardware > > > > > > > In context of legacy is doesn’t matter much given that its over AQ. > > > > Let me give you an example. I feel that device specific config should allow > > arbitrary length accesses so that e.g. > > mac can be read and written atomically. > > > > On the other hand, this is not the case for common config. > > > Why is this not the case with common config? > Spec snippet: "When using the legacy interface the driver MAY access the > device-specific configuration region using any > width accesses"
I mean, what you said above exactly? device-specific configuration excludes common config. > > I feel we do not need to allow e.g. access to both common config and device > > specific one in a single operation, that is just messy. > It is just an offset and value. > What part bothers you? E.g. that it can cross the coundary between common and device config. > > Now sure, we can add text > > with an explanation, but if instead there's a flag saying "this is common > > cfg" > > or "this is device cfg" then it fall out automatically. > > > > Is this a deal breaker? No, but note how neither I nor Jason did not think > > about > > this ahead of the time and the correct usage just falls out of the interface > > automatically. This is a mark of a good interface design. Lots of corner > > cases > > that one has to be careful around is not. > It just moves corner case one layer above in multiple software hypervisors > and hypervisor is not failing it either on cfg read/writes as expected by the > guest. > So bisecting is not adding anything extra. Those failure checks are going to > be ignored in hypervisor anyway. Look we didn't build modern because we wanted to make work, we did because legacy is broken. So either let legacy die already or let's build a sane interface to emulate it please. -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org
