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authorMatt Fleming <matt.fleming@intel.com>2014-02-24 13:37:29 +0000
committerMatt Fleming <matt.fleming@intel.com>2014-03-04 21:43:59 +0000
commit108d3f44b16be2ecf0e44c2f2863752918eb7bce (patch)
treed7b13929ee817e10d174e5344bdcc79ca5d58b3a /arch/x86/boot
parent7d453eee36ae4cf30fc2f2faae54f634c4f863b7 (diff)
downloadop-kernel-dev-108d3f44b16be2ecf0e44c2f2863752918eb7bce.zip
op-kernel-dev-108d3f44b16be2ecf0e44c2f2863752918eb7bce.tar.gz
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>
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/compressed/head_64.S3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 37c741b..4f40cdd 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
/*
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