diff options
| author | Vivek Goyal <vgoyal@in.ibm.com> | 2006-12-07 02:14:04 +0100 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-12-07 02:14:04 +0100 |
| commit | e69f202d0a1419219198566e1c22218a5c71a9a6 (patch) | |
| tree | 16bb59505500797e1ea7e09ee9c3b495ce65b76a /arch/i386/boot/compressed/head.S | |
| parent | 6a044b3a0a1829ef19bb29548ffe553f48e8d80c (diff) | |
[PATCH] i386: Implement CONFIG_PHYSICAL_ALIGN
o Now CONFIG_PHYSICAL_START is being replaced with CONFIG_PHYSICAL_ALIGN.
Hardcoding the kernel physical start value creates a problem in relocatable
kernel context due to boot loader limitations. For ex, if somebody
compiles a relocatable kernel to be run from address 4MB, but this kernel
will run from location 1MB as grub loads the kernel at physical address
1MB. Kernel thinks that I am a relocatable kernel and I should run from
the address I have been loaded at. So somebody wanting to run kernel
from 4MB alignment location (for improved performance regions) can't do
that.
o Hence, Eric proposed that probably CONFIG_PHYSICAL_ALIGN will make
more sense in relocatable kernel context. At run time kernel will move
itself to a physical addr location which meets user specified alignment
restrictions.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Diffstat (limited to 'arch/i386/boot/compressed/head.S')
| -rw-r--r-- | arch/i386/boot/compressed/head.S | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S index e4dd7a6b9b0..f395a4bb38b 100644 --- a/arch/i386/boot/compressed/head.S +++ b/arch/i386/boot/compressed/head.S @@ -26,6 +26,7 @@ #include <linux/linkage.h> #include <asm/segment.h> #include <asm/page.h> +#include <asm/boot.h> .section ".text.head" .globl startup_32 @@ -52,17 +53,17 @@ startup_32: 1: popl %ebp subl $1b, %ebp -/* Compute the delta between where we were compiled to run at - * and where the code will actually run at. +/* %ebp contains the address we are loaded at by the boot loader and %ebx + * contains the address where we should move the kernel image temporarily + * for safe in-place decompression. */ - /* Start with the delta to where the kernel will run at. If we are - * a relocatable kernel this is the delta to our load address otherwise - * this is the delta to CONFIG_PHYSICAL start. - */ + #ifdef CONFIG_RELOCATABLE - movl %ebp, %ebx + movl %ebp, %ebx + addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx + andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx #else - movl $(CONFIG_PHYSICAL_START - startup_32), %ebx + movl $LOAD_PHYSICAL_ADDR, %ebx #endif /* Replace the compressed data size with the uncompressed size */ @@ -94,9 +95,10 @@ startup_32: /* Compute the kernel start address. */ #ifdef CONFIG_RELOCATABLE - leal startup_32(%ebp), %ebp + addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebp + andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp #else - movl $CONFIG_PHYSICAL_START, %ebp + movl $LOAD_PHYSICAL_ADDR, %ebp #endif /* @@ -150,8 +152,8 @@ relocated: * and where it was actually loaded. */ movl %ebp, %ebx - subl $CONFIG_PHYSICAL_START, %ebx - + subl $LOAD_PHYSICAL_ADDR, %ebx + jz 2f /* Nothing to be done if loaded at compiled addr. */ /* * Process relocations. */ |