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From: Kumar Gala <galak@kernel.crashing.org>
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Subject: Re: [RFC][WIP][PATCH] Add IRQSTACKS to ppc32
Date: Thu, 24 Apr 2008 07:59:55 -0500
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On Apr 24, 2008, at 2:18 AM, Benjamin Herrenschmidt wrote:
>
> On Thu, 2008-04-24 at 00:37 -0500, Kumar Gala wrote:
>> +       /*
>> +        * interrupt stacks must be under 256MB, we cannot afford to
>> take
>> +        * SLB misses on them.
>> +        */
>> +       for_each_possible_cpu(i) {
>> +               softirq_ctx[i] = (struct thread_info *)
>> +                       __va(lmb_alloc_base(THREAD_SIZE,
>> +                                           THREAD_SIZE,  
>> 0x10000000));
>> +               hardirq_ctx[i] = (struct thread_info *)
>> +                       __va(lmb_alloc_base(THREAD_SIZE,
>> +                                           THREAD_SIZE,  
>> 0x10000000));
>> +       }
>> +
>
> The comment is a bit bogus :-) (about SLB misses). lowmem is your  
> limit
> I think. Also, why not share the code with ppc64 ?

I'm going to change it to be just lmb_alloc() so it will be difficult  
to share with ppc64 (other than w/an ifdef).

- k