[PATCH V2] powerpc/hugetlb: Add ABI defines for supported HugeTLB page sizes

[Michael Ellerman]

Balbir Singh <bsingharora at gmail.com> writes:
> On Wed, 2017-04-05 at 10:49 +0530, Anshuman Khandual wrote:
>> diff --git a/arch/powerpc/include/uapi/asm/mman.h b/arch/powerpc/include/uapi/asm/mman.h
>> index 03c06ba..3eb788c 100644
>> --- a/arch/powerpc/include/uapi/asm/mman.h
>> +++ b/arch/powerpc/include/uapi/asm/mman.h
>> @@ -29,4 +29,9 @@
>>  #define MAP_STACK	0x20000		/* give out an address that is best suited for process/thread stacks */
>>  #define MAP_HUGETLB	0x40000		/* create a huge page mapping */
>>  
>> +#define MAP_HUGE_2MB	(21 << MAP_HUGE_SHIFT)	/* 2MB HugeTLB Page */
>> +#define MAP_HUGE_16MB	(24 << MAP_HUGE_SHIFT)	/* 16MB HugeTLB Page */
>> +#define MAP_HUGE_1GB	(30 << MAP_HUGE_SHIFT)	/* 1GB HugeTLB Page */
>> +#define MAP_HUGE_16GB	(34 << MAP_HUGE_SHIFT)	/* 16GB HugeTLB Page */
>> +
>>  #endif /* _UAPI_ASM_POWERPC_MMAN_H */
>
> We may want to call out what MMU supports what size, so that an error can
> be interpreted from the header file comments.

No don't, it can depend on what's configured in Linux and/or hypervisor
config and/or firmware and so on, so any header file comments are most
likely just going to be misleading and/or out of date.

cheers