On 15.08.2013, at 08:28, Benjamin Herrenschmidt wrote: > On Thu, 2013-08-15 at 08:10 +0200, Alexander Graf wrote: > >> So you're saying it's good to remove a well established feature on 5% >> of the supported CPUs, leave the others inconsistent with the change >> and then declare the whole thing an improvement? > > WTF are you talking about ? > > To need an exact PVR definition to the last bit means every time a minor > chip rev comes out of IBM, KVM will stop working until qemu is updated > to know about that revision. > > This is dumb.
No disagreement here. > > Being able to emulate a P7 2.1 vs a P7 2.3 is completely pointless since > essentially they expose the same architecture and the bugs that are > fixed between those revisions are for the most part not guest visible > nor even emulated by qemu to begin with. > > Now there *might* be some value in being able to specify among "known > supported" versions for things like P5 (but frankly, who gives a damn ? > Who is actually going to *use* that ? Nobody really ....) > > In that case it's easy ... have a name match with the table entry. Have you read my previous reply? > With the mask & value, you can do like the kernel, ie, have first in the > list the specific entries you want to match against (ie, P7_2_1, > P7_2_3, ...) and fallback to a generic "P7 any revision" entry. That way > qemu will still work if IBM releases a P7 v2.4 you don't know about. > > As for selecting it, similarly, you can do an exact match on the name > (or a partial match as a fallback, I don't care) and pickup the PVR > value out of the table for emulation. > > Point is, what we have now is crap. This is the best fix I've seen so > far. It's useful, cover the 99.9% of the possible use cases I can think > of, but you seem to care more about hypothetical scenario that have no > practical interest on the field. The patch makes things inconsistent. It moves POWER7, POWER7+ and POWER8 to a different model from everything else and removes already existing -cpu names. This is just plain wrong. I want a consistent solution that's future proof. Alex
