On Wed, Dec 18, 2013 at 10:44:08PM +0100, Alexander Graf wrote: > > On 11.11.2013, at 15:02, Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote: > > > From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > > > Don't try to compute these values. > > > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > --- > > > > NOTE: I am not sure why we were originally computing dsisr and dar. So may be > > we need a variant of this patch. But with this and the additional patch > > "powerpc: book3s: PR: Enable Little Endian PR guest" I am able to get a Little Endian > > PR guest to boot. > > It's quite easy to find out - git blame tells you all the history and points you to commit ca7f4203b. > > commit ca7f4203b9b66e12d0d9968ff7dfe781f3a9695a > Author: Alexander Graf <agraf@xxxxxxx> > Date: Wed Mar 24 21:48:28 2010 +0100 > > KVM: PPC: Implement alignment interrupt > > Mac OS X has some applications - namely the Finder - that require alignment > interrupts to work properly. So we need to implement them. > > But the spec for 970 and 750 also looks different. While 750 requires the > DSISR and DAR fields to reflect some instruction bits (DSISR) and the fault > address (DAR), the 970 declares this as an optional feature. So we need > to reconstruct DSISR and DAR manually. > > Signed-off-by: Alexander Graf <agraf@xxxxxxx> > Signed-off-by: Avi Kivity <avi@xxxxxxxxxx> > > Read this as "on 970, alignment interrupts don't give us DSISR and DAR of the faulting instruction" as otherwise I wouldn't have implemented it. Although it's optional, all IBM POWER cpus, and as far as I know all PowerPC cpus, set DAR on an alignment interrupt to the effective address being accessed. You have a valid point regarding DSISR, but it would be nice to skip the computations where either the host CPU provides the bits, or the virtual CPU doesn't. Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
