From 6a50a664ca0cfd2a487525f10cec3ff4d570b5e8 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 2 May 2007 19:27:08 +0200 Subject: [PATCH] x86-64: build-time checking o X86_64 kernel should run from 2MB aligned address for two reasons. - Performance. - For relocatable kernels, page tables are updated based on difference between compile time address and load time physical address. This difference should be multiple of 2MB as kernel text and data is mapped using 2MB pages and PMD should be pointing to a 2MB aligned address. Life is simpler if both compile time and load time kernel addresses are 2MB aligned. o Flag the error at compile time if one is trying to build a kernel which does not meet alignment restrictions. Signed-off-by: Vivek Goyal Signed-off-by: Andi Kleen Cc: "Eric W. Biederman" Cc: Andi Kleen Signed-off-by: Andrew Morton --- include/asm-x86_64/page.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h index 40a24d0df09..b17fc16ec2e 100644 --- a/include/asm-x86_64/page.h +++ b/include/asm-x86_64/page.h @@ -78,6 +78,7 @@ extern unsigned long phys_base; #endif /* !__ASSEMBLY__ */ #define __PHYSICAL_START CONFIG_PHYSICAL_START +#define __KERNEL_ALIGN 0x200000 #define __START_KERNEL (__START_KERNEL_map + __PHYSICAL_START) #define __START_KERNEL_map 0xffffffff80000000 #define __PAGE_OFFSET 0xffff810000000000 -- cgit v1.2.3