Re: 1M hugepage size being registered on Linux

On Wed, 2017-06-21 at 20:33 +1000, Michael Ellerman wrote:

victora [off-list ref] writes:

quoted

Hi Alistair/Jeremy,

I am working on a bug related to 1M hugepage size being registered on 
Linux (Power 8 Baremetal - Garrison).

Wasn't that caused by a firmware bug?

quoted

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?

Does it work? :)

The user manual says it's a supported size, but I thought it didn't work
(in hardware) for some reason.

Right, I thought there was some config bit to switch between 1M and 16M
and that had never been fully verified ? I don't remember the details.