On Tue, 06 Dec 2011 11:57:20 +0200, Sasha Levin <[email protected]> wrote: > On Tue, 2011-12-06 at 11:47 +0200, Pekka Enberg wrote: > > On Tue, Dec 6, 2011 at 10:45 AM, Sasha Levin <[email protected]> > > wrote: > > > Rusty has just removed it out of the spec. Since we probably the only ones > > > who implemented support for it, we should remove it out of our code as > > > well. > > > > > > There is no issue with breaking anything since nothing else worked with > > > it, > > > so it's fully backwards compatible. > > > > > > Cc: Rusty Russell <[email protected]> > > > Signed-off-by: Sasha Levin <[email protected]> > > > > Applied, thanks! > > > > How is this going to work going forward? Should I ask Rusty for an ACK > > before merging code that implements some (new) part of the virtio > > spec? I like the fact that we're bleeding edge but it's pointless for > > everyone involved if we implement something that's known to be > > half-baked in the spec. > > There was a little cheating involved here since the spec basically broke > backwards compatibility by removing 64 bit features, so it's a special > case and probably won't happen (too many times) again. > > Half baked features usually don't go into the spec as well, Rusty > usually insists on having a working code besides just spec updates, so > again - this was one of those rare special cases. > > If Rusty or Michael could ACK our virtio patches it would be awesome.
Acked-by: Rusty Russell <[email protected]> TLDR version: I shouldn't have put it in the spec until we needed it. The spec revert broke no guests, because no guest ever implemented high feature bits (both because it wasn't in the draft spec long, and no device defined > 32 features yet, so no guest needed to). It also broke no hosts, since it was up to the host to offer the high feature bits. No host did, since no device needed those high bits. kvmtool guys are just enthusiasts, so they put in the infrastructure, but didn't use it. If I'm wrong, then when we use bit 31 for something else, a new guest may break. It may happen, but we're going to 64 bits in a different manner, so we can avoid using bit 31 for a long time. It's very unusual for me to un-spec things, but in this very limited case it fairly safe. Cheers, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
