From: Matt Fleming Date: Mon, 24 Feb 2014 13:37:29 +0000 (+0000) Subject: x86/boot: Don't overwrite cr4 when enabling PAE X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=108d3f44b16be2ecf0e44c2f2863752918eb7bce;p=linux-beck.git x86/boot: Don't overwrite cr4 when enabling PAE Some EFI firmware makes use of the FPU during boottime services and clearing X86_CR4_OSFXSR by overwriting %cr4 causes the firmware to crash. Add the PAE bit explicitly instead of trashing the existing contents, leaving the rest of the bits as the firmware set them. Cc: H. Peter Anvin Signed-off-by: Matt Fleming --- diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 37c741b0d2ac..4f40cddd025d 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -113,7 +113,8 @@ ENTRY(startup_32) lgdt gdt(%ebp) /* Enable PAE mode */ - movl $(X86_CR4_PAE), %eax + movl %cr4, %eax + orl $X86_CR4_PAE, %eax movl %eax, %cr4 /*