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Groups > linux.kernel > #1713818
| From | "Kirill A. Shutemov" <kirill@shutemov.name> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable |
| Date | 2017-08-17 13:00 +0200 |
| Message-ID | <ufqGS-3Hy-3@gated-at.bofh.it> (permalink) |
| References | <ucch3-8wk-3@gated-at.bofh.it> <ucch4-8wk-15@gated-at.bofh.it> <ufoYr-2Kf-59@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Aug 17, 2017 at 11:00:38AM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote: > > > For boot-time switching between 4- and 5-level paging we need to be able > > to fold p4d page table level at runtime. It requires variable > > PGDIR_SHIFT and PTRS_PER_P4D. > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > --- > > arch/x86/boot/compressed/kaslr.c | 5 +++++ > > arch/x86/include/asm/pgtable_32.h | 2 ++ > > arch/x86/include/asm/pgtable_32_types.h | 2 ++ > > arch/x86/include/asm/pgtable_64_types.h | 15 +++++++++++++-- > > arch/x86/kernel/head64.c | 9 ++++++++- > > arch/x86/mm/dump_pagetables.c | 12 +++++------- > > arch/x86/mm/init_64.c | 2 +- > > arch/x86/mm/kasan_init_64.c | 2 +- > > arch/x86/platform/efi/efi_64.c | 4 ++-- > > include/asm-generic/5level-fixup.h | 1 + > > include/asm-generic/pgtable-nop4d.h | 1 + > > include/linux/kasan.h | 2 +- > > mm/kasan/kasan_init.c | 2 +- > > 13 files changed, 43 insertions(+), 16 deletions(-) > > So I'm wondering what the code generation effect of this is - what's the > before/after vmlinux size? > > My guess is that the effect should be very small, as these constants are not > widely used - but I'm only guessing and could be wrong. This change increase vmlinux size for defconfig + X86_5LEVEL=y by ~4k or 0.01%. -- Kirill A. Shutemov
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Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable Ingo Molnar <mingo@kernel.org> - 2017-08-17 11:10 +0200
Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-08-17 13:00 +0200
Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable Ingo Molnar <mingo@kernel.org> - 2017-08-17 13:20 +0200
Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-08-21 17:30 +0200
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