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Date: Mon, 15 Jul 2013 11:55:11 -0500
From: Scott Wood <scottwood@freescale.com>
Subject: Re: [PATCH] powerpc/fsl-booke: Work around erratum A-006958
To: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
References: <1373677412-24329-1-git-send-email-scottwood@freescale.com>
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In-Reply-To: <87mwpojr6d.fsf@linux.vnet.ibm.com> (from
 aneesh.kumar@linux.vnet.ibm.com on Mon Jul 15 01:03:22 2013)
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On 07/15/2013 01:03:22 AM, Aneesh Kumar K.V wrote:
> Scott Wood <scottwood@freescale.com> writes:
>=20
>=20
>=20
> > diff --git a/arch/powerpc/platforms/Kconfig.cputype =20
> b/arch/powerpc/platforms/Kconfig.cputype
> > index ae0aaea..7f0e2e5 100644
> > --- a/arch/powerpc/platforms/Kconfig.cputype
> > +++ b/arch/powerpc/platforms/Kconfig.cputype
> > @@ -165,6 +165,17 @@ config PPC_E500MC
> >  	  such as e5500/e6500), and must be disabled for running on
> >  	  e500v1 or e500v2.
> >
> > +config FSL_ERRATUM_A_006958
> > +	bool
> > +	depends on PPC_E500MC && PPC64
> > +	default y
> > +	help
> > +	  Workaround for erratum A-006958, which says that 64-bit
> > +	  timebase reads are not atomic.  The workaround is to fall back
> > +	  to the 32-bit method of reading timebase.  Note that timebase
> > +	  is readable by userspace, so any non-vdso userspace accesses
> > +	  will need to have the workaround applied separately.
> > +
> >  config PPC_FPU
> >  	bool
> >  	default y if PPC64
>=20
>=20
> I am completely new to this area, so ignore if it is silly. But how do
> we expect to select this config ? Should that happen via .config ?

It will automatically be selected if PPC_E500MC and PPC64 are both =20
selected.

-Scott=