[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>
diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S
index e4dd7a6..f395a4b 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 @@
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 @@
/* 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 @@
* 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.
*/
diff --git a/arch/i386/boot/compressed/misc.c b/arch/i386/boot/compressed/misc.c
index 4eac24e..dc15389 100644
--- a/arch/i386/boot/compressed/misc.c
+++ b/arch/i386/boot/compressed/misc.c
@@ -14,6 +14,7 @@
#include <linux/screen_info.h>
#include <asm/io.h>
#include <asm/page.h>
+#include <asm/boot.h>
/* WARNING!!
* This code is compiled with -fPIC and it is relocated dynamically
@@ -360,12 +361,12 @@
insize = input_len;
inptr = 0;
- if (((u32)output - CONFIG_PHYSICAL_START) & 0x3fffff)
- error("Destination address not 4M aligned");
+ if ((u32)output & (CONFIG_PHYSICAL_ALIGN -1))
+ error("Destination address not CONFIG_PHYSICAL_ALIGN aligned");
if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff))
error("Destination address too large");
#ifndef CONFIG_RELOCATABLE
- if ((u32)output != CONFIG_PHYSICAL_START)
+ if ((u32)output != LOAD_PHYSICAL_ADDR)
error("Wrong destination address");
#endif