Re: [RFC] Implementing HUGEPAGE on MPC 8xx

On Wed, 2016-06-08 at 09:03 +0200, Christophe Leroy wrote:

In see in the current ppc kernel that for PPC32, SYS_SUPPORTS_HUGETLBFS 
is selected only if we have PHYS_64BIT.
What is the reason for only implementing HUGETLBFS with 64 bits phys 
addresses ?

That's not for PPC32 in general -- it's for 32-bit FSL Book E.  The reason for
the limitation is that there are separate TLB miss handlers depending on
whether PHYS_64BIT is enabled, and we didn't want to have to implement hugetlb
support in both of them unless there was actual demand for it.

 From your point of view, what would be the best approach to extend 
support of HUGE PAGES to PPC_8xx ?
Would the good starting point be to implement a hugepagetlb-8xx.c from 
hugepagetlb-book3e.c ?

Yes.

-Scott