Le 11/04/2024 à 18:15, Peter Xu a écrit : > 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? Depends on what you expect by "soon". I sure won't be able to send any RFC before end of April. Should be possible to have something during May. Christophe
