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Date: Tue, 4 Mar 2014 13:14:20 +0000 From: Matt Fleming <matt@...sole-pimps.org> To: linux-efi@...r.kernel.org Cc: "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>, Alan Cox <alan@...rguk.ukuu.org.uk>, Matthew Garrett <mjg59@...f.ucam.org>, linux-kernel@...r.kernel.org, Matt Fleming <matt.fleming@...el.com> Subject: [PATCH 12/13] x86/boot: Don't overwrite cr4 when enabling PAE From: Matt Fleming <matt.fleming@...el.com> 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@...or.com> Signed-off-by: Matt Fleming <matt.fleming@...el.com> --- arch/x86/boot/compressed/head_64.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) 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 /* -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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