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." Signed-off-by: Bjorn Helgaas <bjorn.helgaas@xxxxxx> --- arch/x86/include/asm/e820.h | 3 +++ arch/x86/kernel/resource.c | 3 ++- 2 files changed, 5 insertions(+), 1 deletions(-) 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; diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c index 89638af..2a26819 100644 --- a/arch/x86/kernel/resource.c +++ b/arch/x86/kernel/resource.c @@ -37,10 +37,11 @@ static void remove_e820_regions(struct resource *avail) void arch_remove_reservations(struct resource *avail) { - /* Trim out BIOS area (low 1MB) and E820 regions */ + /* Trim out BIOS areas (low 1MB and high 2MB) and E820 regions */ if (avail->flags & IORESOURCE_MEM) { if (avail->start < BIOS_END) avail->start = BIOS_END; + resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END); remove_e820_regions(avail); } -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
