On Thu, Aug 17, 2017 at 11:00:38AM +0200, Ingo Molnar wrote: > > * Kirill A. Shutemov <[email protected]> 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 <[email protected]> > > --- > > 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
