From a2c606d53ab71dee6410f10ef0adf67321d60e06 Mon Sep 17 00:00:00 2001 From: Bjorn Helgaas Date: Thu, 16 Dec 2010 10:39:02 -0700 Subject: 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 Signed-off-by: Bjorn Helgaas Signed-off-by: Jesse Barnes --- arch/x86/include/asm/e820.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h index 5be1542..e99d55d 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; -- cgit v1.1