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

[Andreas Färber]

Am 21.05.2011 um 03:58 schrieb Alexander Graf:

> Am 21.05.2011 um 00:37 schrieb Andreas Färber  
> <address@hidden>:
>
> > 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 :)
> >
> > Nack, this does not fix ppc64 for me! How did you test it, Alex???
>
> I booted a ppc64 kernel on a ppc64 Linux system with tcg and it  
> booted fine for me. Maybe you're hitting yet another issue?

Which OpenBIOS did you use? The 32-bit version using mtsrin works now,  
but not the 64-bit HEAD version that I attached, which uses slb*  
instructions instead.

Andreas