1M hugepage size being registered on Linux

[Michael Ellerman]

Michal Suchánek <msuchanek at suse.de> writes:

> On Tue, 20 Jun 2017 10:47:47 -0300
> victora <victora at linux.vnet.ibm.com> wrote:
>
>> Hi Alistair/Jeremy,
>> 
>> I am working on a bug related to 1M hugepage size being registered on 
>> Linux (Power 8 Baremetal - Garrison).
>> 
>> I was checking dmesg and it seems that 1M page size is coming from 
>> firmware to Linux.
>> 
>> [    0.000000] base_shift=20: shift=20, sllp=0x0130,
>> avpnm=0x00000000, tlbiel=0, penc=2
>> [    1.528867] HugeTLB registered 1 MB page size, pre-allocated 0
>> pages
>> 
>> Should Linux support this page size? As afar as I know, this was an 
>> unsupported page size in the past isn't it? If this should be
>> supported now, is there any specific reason for that?
>
> Hello,
>
> a525108cf1cc powerpc/mm/hugetlb: Filter out hugepage size not supported
> by page table layout
>
> Should reject unsupported huge page sizes, right?

Yes, see my reply.

cheers