Commit 108d3f44 authored Feb 24, 2014 by Matt Fleming

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 <hpa@zytor.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

parent 7d453eee

arch/x86/boot/compressed/head_64.S

+2 −1

Original line number	Diff line number	Diff line
		@@ -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

		/*