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authorBjorn Helgaas <bjorn.helgaas@hp.com>2010-12-16 20:39:02 +0300
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-12-17 21:01:30 +0300
commita2c606d53ab71dee6410f10ef0adf67321d60e06 (patch)
tree7a4cf519cbfc01fd1c4273c1481f40f4cd7d00bc /arch/x86/include/asm/e820.h
parent4dc2287c1805e7fe8a7cb90bbcd44abee8cdb914 (diff)
downloadlinux-a2c606d53ab71dee6410f10ef0adf67321d60e06.tar.xz
x86: avoid high BIOS area when allocating address space
This prevents allocation of the last 2MB before 4GB. The experiment described here shows Windows 7 ignoring the last 1MB: https://bugzilla.kernel.org/show_bug.cgi?id=23542#c27 This patch ignores the top 2MB instead of just 1MB because H. Peter Anvin says "There will be ROM at the top of the 32-bit address space; it's a fact of the architecture, and on at least older systems it was common to have a shadow 1 MiB below." Acked-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'arch/x86/include/asm/e820.h')
-rw-r--r--arch/x86/include/asm/e820.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
index 5be1542fbfaf..e99d55d74df5 100644
--- a/arch/x86/include/asm/e820.h
+++ b/arch/x86/include/asm/e820.h
@@ -72,6 +72,9 @@ struct e820map {
#define BIOS_BEGIN 0x000a0000
#define BIOS_END 0x00100000
+#define BIOS_ROM_BASE 0xffe00000
+#define BIOS_ROM_END 0xffffffff
+
#ifdef __KERNEL__
/* see comment in arch/x86/kernel/e820.c */
extern struct e820map e820;