[PATCH] [POWERPC] 4xx: Use virtual PVR value to init FPU on arch/ppc 440EP
Josh Boyer
jwboyer at linux.vnet.ibm.com
Sat Nov 17 06:23:08 EST 2007
On Fri, 16 Nov 2007 13:20:09 -0600
Kumar Gala <galak at kernel.crashing.org> wrote:
>
> On Nov 16, 2007, at 11:29 AM, Josh Boyer wrote:
>
> > This fixes arch/ppc 440EP platforms to setup the FPU correctly. A
> > virtual
> > PVR is used, as 440GR platforms share an identical hardware PVR
> > value and do
> > not have an FPU.
> >
> > Signed-off-by: Josh Boyer <jwboyer at linux.vnet.ibm.com>
> > Index: linux-2.6/arch/ppc/kernel/setup.c
> > ===================================================================
> > --- linux-2.6.orig/arch/ppc/kernel/setup.c
> > +++ linux-2.6/arch/ppc/kernel/setup.c
> > @@ -312,7 +312,14 @@ early_init(int r3, int r4, int r5)
> > * Identify the CPU type and fix up code sections
> > * that depend on which cpu we have.
> > */
> > +#if defined(CONFIG_440EP) && defined(CONFIG_PPC_FPU)
> > + /* We pass the virtual PVR here for 440EP as 440EP and 440GR have
> > + * identical PVRs and there is no reliable way to check for the FPU
> > + */
> > + spec = identify_cpu(offset, (mfspr(SPRN_PVR) | 0x8));
> > +#else
> > spec = identify_cpu(offset, mfspr(SPRN_PVR));
> > +#endif
> > do_feature_fixups(spec->cpu_features,
> > PTRRELOC(&__start___ftr_fixup),
> > PTRRELOC(&__stop___ftr_fixup));
>
> Are we really adding support for new processors to arch/ppc?
No. This is to continue to support 440EP FPU in arch/ppc. Commit
d1dfc35d3a62 switched the cputable around for EP(x)/GR(x) and arch/ppc wasn't fixed up. So without the above patch, 440EP gets detected as 440GR and the FPU isn't initialized properly.
josh
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