Le 26/02/2020 à 11:56, Mike Rapoport a écrit : > On Wed, Feb 26, 2020 at 10:46:13AM +0100, Christophe Leroy wrote: >> >> >> Le 26/02/2020 à 10:13, Mike Rapoport a écrit : >>> On Tue, Feb 18, 2020 at 12:54:40PM +0200, Mike Rapoport wrote: >>>> On Sun, Feb 16, 2020 at 11:41:07AM +0100, Christophe Leroy wrote: >>>>> >>>>> >>>>> Le 16/02/2020 à 09:18, Mike Rapoport a écrit : >>>>>> From: Mike Rapoport <rppt****@linux*****> >>>>>> >>>>>> Implement primitives necessary for the 4th level folding, add walks of p4d >>>>>> level where appropriate and replace 5level-fixup.h with pgtable-nop4d.h. >>>>> >>>>> I don't think it is worth adding all this additionnals walks of p4d, this >>>>> patch could be limited to changes like: >>>>> >>>>> - pud = pud_offset(pgd, gpa); >>>>> + pud = pud_offset(p4d_offset(pgd, gpa), gpa); >>>>> >>>>> The additionnal walks should be added through another patch the day powerpc >>>>> need them. >>>> >>>> Ok, I'll update the patch to reduce walking the p4d. >>> >>> Here's what I have with more direct acceses from pgd to pud. >> >> I went quickly through. This looks promising. >> >> Do we need the walk_p4d() in arch/powerpc/mm/ptdump/hashpagetable.c ? >> Can't we just do >> >> @@ -445,7 +459,7 @@ static void walk_pagetables(struct pg_state *st) >> addr = KERN_VIRT_START + i * PGDIR_SIZE; >> if (!pgd_none(*pgd)) >> /* pgd exists */ >> - walk_pud(st, pgd, addr); >> + walk_pud(st, p4d_offset(pgd, addr), addr); > > We can do > > addr = KERN_VIRT_START + i * PGDIR_SIZE; > p4d = p4d_offset(pgd, addr); > if (!p4d_none(*pgd)) > walk_pud() > > But I don't think this is really essential. Again, we are trading off code > consistency vs line count. I don't think line count is that important. Ok. Christophe
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