On Mon, Aug 21, 2017 at 06:29:03PM +0300, Kirill A. Shutemov wrote: > This patch prepare decompression code to boot-time switching between 4- > and 5-level paging. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > --- > arch/x86/boot/compressed/head_64.S | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S > index fbf4c32d0b62..2e362aea3319 100644 > --- a/arch/x86/boot/compressed/head_64.S > +++ b/arch/x86/boot/compressed/head_64.S > @@ -347,6 +347,28 @@ preferred_addr: > leaq boot_stack_end(%rbx), %rsp > > #ifdef CONFIG_X86_5LEVEL > + /* Preserve rbx across cpuid */ > + movq %rbx, %r8 > + > + /* Check if leaf 7 is supported */ > + movl $0, %eax Use xor instead, it should be shorter > + cpuid > + cmpl $7, %eax > + jb lvl5 > + > + /* > + * Check if la57 is supported. > + * The feature is enumerated with CPUID.(EAX=07H, ECX=0):ECX[bit 16] > + */ > + movl $7, %eax > + movl $0, %ecx same -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
