Re: [Qemu-devel] [Qemu-ppc] [PATCH 3/6] target-ppc: Extend FPU state for newer POWER CPUs

[David Gibson <dwg@au1.ibm.com>]

On Wed, Sep 26, 2012 at 08:36:45AM +0200, Aurelien Jarno wrote:
> On Wed, Sep 26, 2012 at 01:12:18PM +1000, David Gibson wrote:
> > This patch adds some extra FPU state to CPUPPCState.  Specifically, fpscr
> > is extended to 64 bits, since some recent CPUs now have more status bits
> > than fit inside 64 bits, and we add the 32 VSR registers present on CPUs
> > with VSX (these extend the standard FP regs, which together with the
> > Altivec/VMX registers form a 64 x 128bit register file for VSX).
> > 
> > We don't actually support the instructions using these extra registers in
> > TCG yet, but we still a place to store the state so we can sync it with
> > KVM and savevm/loadvm it.  This patch updates the savevm code to not
> > fail on the extended state, but also does not actually save it - that's
> > a project for another patch.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  target-ppc/cpu.h       |    4 +++-
> >  target-ppc/machine.c   |    8 ++++++--
> >  target-ppc/translate.c |    2 +-
> >  3 files changed, 10 insertions(+), 4 deletions(-)
> > 
> > diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
> > index faf4404..846778f 100644
> > --- a/target-ppc/cpu.h
> > +++ b/target-ppc/cpu.h
> > @@ -963,7 +963,7 @@ struct CPUPPCState {
> >      /* floating point registers */
> >      float64 fpr[32];
> >      /* floating point status and control register */
> > -    uint32_t fpscr;
> > +    uint64_t fpscr;
> 
> This will break the TCG code, as fpscr is mapped as an i32 in TCG. Also
> if it is 64-bit only on PPC64 machines, it might be a good idea to
> change it to target_ulong instead, and use _tl in the TCG code.

Ah, good point, thanks for catching that.  Both changes made for the
next version.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson