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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH 2/2] powerpc: Make context bits depend on virtual addr
 size.
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Date: Wed, 13 Feb 2013 08:54:16 +0530
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Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> On Wed, 2013-02-13 at 00:01 +0530, Aneesh Kumar K.V wrote:
>> + * Be careful with this value. This determines the VSID_MODULUS_*  and that
>> + * need to be co-prime with VSID_MULTIPLIER*
>> + */
>> +#if defined(CONFIG_POWER6_CPU) || defined(CONFIG_POWER7_CPU)
>> +/*
>> + * Even if cpu support 68 bits, we limit this to 66 because
>> + * we support only 2^19 context.
>> + */
>> +#define MAX_VIRTUAL_ADDR_BITS 66
>> +#else
>> +/* power4,power 5 and cell is 65 */
>> +#define MAX_VIRTUAL_ADDR_BITS 65
>> +#endif
>> +
>
> A compile option ? Really ? Ugh...

I actually wanted that to be done in Kconfig.cputype, but haven't found
a nice way to do it. Considering we are switching between only two
values, I was thinking an #ifdef would work.

-aneesh