Re: pat support in the kernel

Andi Kleen writes:
 > [e-mail] writes:
 > 
 > > (Large pages ignoring PAT index bit 2, or something like that.)
 > 
 > change_page_attr will force 4K pages for these anyways, so for the kernel
 > direct mapping it should not be an issue. 
 > 
 > For the hugetlbfs user mapping you may need to check the case, but
 > it's probably reasonable to EINVAL there.
 > 
 > Other than that everything should be 4K mapped.

The bug is that 4K pages get the wrong PAT index; the large page
thing is the trigger but the large pages themselves arent' affected.

So 4K pages need to be restricted to the low 4 PAT types.