Re: [Qemu-devel] [PATCH] PPC: Allow book3s ppc32 to run dcbzl

[Alexander Graf]

On 01/29/2013 07:02 PM, Scott Wood wrote:
> On 01/29/2013 07:52:58 AM, Alexander Graf wrote:
> > The bit that makes a dcbz instruction a dcbzl instruction was 
> > declared as
> > reserved in ppc32 ISAs. However, hardware simply ignores the bit, making
> > code valid if it simply invokes dcbzl instead of dcbz even on 750 and 
> > G4.
> >
> > Thus, mark the bit as unreserved so that we properly emulate a simple 
> > dcbz
> > in case we're running on non-G5s.
>
> FWIW, dcbzl exists on e500mc, which is 32-bit.  If we ever support 
> L1CSR0[DCBZ32] on e500mc, we'll need proper dcbzl support rather than 
> just a dcbz alias.

Then the e500 machine wouldn't set PPC_CACHE_DCBZ, but a special 
PPC_CACHE_E500MC. Just like 970 sets PPC_CACHE_DCBZT instead today.

Unless of course we can somehow get to the cpu class from env. Then we 
could also ask for the machine type and implement dcbzl accordingly.


Alex