Subject: Re: [PATCH V2 23/68] powerpc/mm: Make page table size a variable

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Sun, 17 Apr 2016 15:57:11 +0530

Balbir Singh <[email-masked]> writes:

>> index 2f818cbd8aa6..dcb9d6e94a0c 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hash-4k.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hash-4k.h
>> @@ -5,48 +5,20 @@
>>   * for each page table entry.  The PMD and PGD level use a 32b record for
>>   * each entry by assuming that each entry is page aligned.
>>   */
>> -#define PTE_INDEX_SIZE  9
>> -#define PMD_INDEX_SIZE  7
>> -#define PUD_INDEX_SIZE  9
>> -#define PGD_INDEX_SIZE  9
>> +#define H_PTE_INDEX_SIZE  9
>> +#define H_PMD_INDEX_SIZE  7
>> +#define H_PUD_INDEX_SIZE  9
>> +#define H_PGD_INDEX_SIZE  9
>>  
>
> Any comments on where these numbers came from?
>
> From these numbers for 4K pages we have
>
> Each PMD is 2M
> Each PUD is 256M
> Each PGD is 128G

I am not sure I understand. We are updating linux page table details for
hash config here. This patch doesn't make any functionality change, it
just make sure few #defines are marked as a variable.

-aneesh