Messages in this thread | | | Date | Thu, 17 Aug 2017 11:00:38 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCHv4 08/14] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable |
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* 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.
Thanks,
Ingo
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