On Mon, Mar 25, 2024 at 01:38:40PM -0300, Jason Gunthorpe wrote: > On Mon, Mar 25, 2024 at 03:55:53PM +0100, Christophe Leroy wrote: > > This series reimplements hugepages with hugepd on powerpc 8xx. > > > > Unlike most architectures, powerpc 8xx HW requires a two-level > > pagetable topology for all page sizes. So a leaf PMD-contig approach > > is not feasible as such. > > > > Possible sizes are 4k, 16k, 512k and 8M. > > > > First level (PGD/PMD) covers 4M per entry. For 8M pages, two PMD entries > > must point to a single entry level-2 page table. Until now that was > > done using hugepd. This series changes it to use standard page tables > > where the entry is replicated 1024 times on each of the two pagetables > > refered by the two associated PMD entries for that 8M page. > > > > At the moment it has to look into each helper to know if the > > hugepage ptep is a PTE or a PMD in order to know it is a 8M page or > > a lower size. I hope this can me handled by core-mm in the future. > > > > There are probably several ways to implement stuff, so feedback is > > very welcome. > > I thought it looks pretty good! I second it. I saw the discussions in patch 1. Christophe, I suppose you're exploring the big hammer over hugepd, and perhaps went already with the 32bit pmd solution for nohash/32bit challenge you mentioned? I'm trying to position my next step; it seems like at least I should not adding any more hugepd code, then should I go with ARCH_HAS_HUGEPD checks, or you're going to have an RFC soon then I can base on top? Thanks, -- Peter Xu
