Re: [Qemu-devel] [PATCH] Fix a bug in mtsr/mtsrin emulation on ppc64

[Andreas Färber]

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?

Andreas