On 21.05.2011, at 13:13, David Gibson wrote: > On Sat, May 21, 2011 at 11:46:12AM +0200, Alexander Graf wrote: >> >> On 21.05.2011, at 11:40, Andreas Färber wrote: >> >>> Am 20.05.2011 um 09:40 schrieb Alexander Graf: >>> >>>> On 20.05.2011, at 05:34, David Gibson wrote: >>>> >>>>> Early ppc64 CPUs include a hack to partially simulate the ppc32 segment >>>>> registers, by translating writes to them into writes to the SLB. This is >>>>> not used by any current Linux kernel, but it is used by the openbios used >>>>> in the qemu mac99 model. >>>>> >>>>> Commit 81762d6dd0d430d87024f2c83e9c4dcc4329fb7d, cleaning up the SLB >>>>> handling introduced a bug in this code, breaking the openbios currently in >>>>> qemu. Specifically, there was an off by one error bitshuffling the >>>>> register format used by mtsr into the format needed for the SLB load, >>>>> causing the flag bits to end up in the wrong place. This caused the >>>>> storage keys to be wrong under openbios, meaning that the translation code >>>>> incorrectly thought a legitimate access was a permission violation. >>>>> >>>>> This patch fixes the bug, at the same time it fixes some build bug in the >>>>> MMU debugging code (only exposed when DEBUG_MMU is enabled). >>>> >>>> Thanks, applied to ppc-next :) >>> >>> Hm. Don't you think we should split off the unrelated debug code fix for >>> bisecting? >> >> Not sure if it's worth the effort. If you were bisecting before >> that, you probably had DEBUG_MMU disabled anyways, because you'd >> otherwise get build breakages before that specific commit anyways, >> so the commit behaves as if it's only the SLB fix. > > Right, I don't see how the debug fixes break bisect in any way. Or > least not in any way they werem't already broken.
Yup, let's just make sure to have you submit separate patches next time, so everyone is happy :) Alex
