From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] [POWERPC] 4xx: Use virtual PVR value to init FPU on arch/ppc 440EP
Date: Fri, 16 Nov 2007 13:23:08 -0600 [thread overview]
Message-ID: <20071116132308.2201e235@weaponx> (raw)
In-Reply-To: <96AAE1CB-3F7F-4231-AD52-01F358E01594@kernel.crashing.org>
On Fri, 16 Nov 2007 13:20:09 -0600
Kumar Gala <galak@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@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
prev parent reply other threads:[~2007-11-16 19:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-16 17:29 [PATCH] [POWERPC] 4xx: Use virtual PVR value to init FPU on arch/ppc 440EP Josh Boyer
2007-11-16 19:20 ` Kumar Gala
2007-11-16 19:23 ` Josh Boyer [this message]
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