diff options
| author | Vivek Goyal <vgoyal@in.ibm.com> | 2007-05-02 19:27:08 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2007-05-02 19:27:08 +0200 |
| commit | 6a50a664ca0cfd2a487525f10cec3ff4d570b5e8 (patch) | |
| tree | cf68fae284a7b44df616a8112e9088557ad31d76 /arch/x86_64/kernel | |
| parent | 1ab60e0f72f71ec54831e525a3e1154f1c092408 (diff) | |
[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 <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/x86_64/kernel')
| -rw-r--r-- | arch/x86_64/kernel/head64.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/head64.c b/arch/x86_64/kernel/head64.c index 6c34bdd22e2..213d90e0475 100644 --- a/arch/x86_64/kernel/head64.c +++ b/arch/x86_64/kernel/head64.c @@ -62,6 +62,13 @@ void __init x86_64_start_kernel(char * real_mode_data) { int i; + /* + * Make sure kernel is aligned to 2MB address. Catching it at compile + * time is better. Change your config file and compile the kernel + * for a 2MB aligned address (CONFIG_PHYSICAL_START) + */ + BUILD_BUG_ON(CONFIG_PHYSICAL_START & (__KERNEL_ALIGN - 1)); + /* clear bss before set_intr_gate with early_idt_handler */ clear_bss(); |