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[PATCH] kexec: x86: add CONFIG_PYSICAL_START

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For one kernel to report a crash another kernel has created we need
to have 2 kernels loaded simultaneously in memory.  To accomplish this
the two kernels need to built to run at different physical addresses.

This patch adds the CONFIG_PHYSICAL_START option to the x86 kernel
so we can do just that.  You need to know what you are doing and
the ramifications are before changing this value, and most users
won't care so I have made it depend on CONFIG_EMBEDDED

bzImage kernels will work and run at a different address when compiled
with this option but they will still load at 1MB.  If you need a kernel
loaded at a different address as well you need to boot a vmlinux.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Eric W. Biederman 2005-06-25 14:57:49 -07:00 committed by Linus Torvalds
parent 5ded01e83e
commit 3d345e3fc9
5 changed files with 23 additions and 7 deletions
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11
arch/i386/Kconfig
View File

@ -942,6 +942,17 @@ config SECCOMP
source kernel/Kconfig.hz
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if EMBEDDED
default "0x100000"
help
This gives the physical address where the kernel is loaded.
Primarily used in the case of kexec on panic where the
fail safe kernel needs to run at a different address than
the panic-ed kernel.
Don't change this unless you know what you are doing.
endmenu

7
arch/i386/boot/compressed/head.S
View File

@ -25,6 +25,7 @@
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page.h>
.globl startup_32
@ -74,7 +75,7 @@ startup_32:
popl %esi # discard address
popl %esi # real mode pointer
xorl %ebx,%ebx
ljmp $(__BOOT_CS), $0x100000
ljmp $(__BOOT_CS), $__PHYSICAL_START
/*
* We come here, if we were loaded high.
@ -99,7 +100,7 @@ startup_32:
popl %ecx # lcount
popl %edx # high_buffer_start
popl %eax # hcount
movl $0x100000,%edi
movl $__PHYSICAL_START,%edi
cli # make sure we don't get interrupted
ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
@ -124,5 +125,5 @@ move_routine_start:
movsl
movl %ebx,%esi # Restore setup pointer
xorl %ebx,%ebx
ljmp $(__BOOT_CS), $0x100000
ljmp $(__BOOT_CS), $__PHYSICAL_START
move_routine_end:

7
arch/i386/boot/compressed/misc.c
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@ -13,6 +13,7 @@
#include <linux/vmalloc.h>
#include <linux/tty.h>
#include <asm/io.h>
#include <asm/page.h>
/*
* gzip declarations
@ -308,7 +309,7 @@ static void setup_normal_output_buffer(void)
#else
if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
#endif
output_data = (char *)0x100000; /* Points to 1M */
output_data = (char *)__PHYSICAL_START; /* Normally Points to 1M */
free_mem_end_ptr = (long)real_mode;
}
@ -333,8 +334,8 @@ static void setup_output_buffer_if_we_run_high(struct moveparams *mv)
low_buffer_size = low_buffer_end - LOW_BUFFER_START;
high_loaded = 1;
free_mem_end_ptr = (long)high_buffer_start;
if ( (0x100000 + low_buffer_size) > ((ulg)high_buffer_start)) {
high_buffer_start = (uch *)(0x100000 + low_buffer_size);
if ( (__PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
high_buffer_start = (uch *)(__PHYSICAL_START + low_buffer_size);
mv->hcount = 0; /* say: we need not to move high_buffer */
}
else mv->hcount = -1;

2
arch/i386/kernel/vmlinux.lds.S
View File

@ -14,7 +14,7 @@ ENTRY(phys_startup_32)
jiffies = jiffies_64;
SECTIONS
{
. = LOAD_OFFSET + 0x100000;
. = __KERNEL_START;
phys_startup_32 = startup_32 - LOAD_OFFSET;
/* read-only */
_text = .; /* Text and read-only data */

3
include/asm-i386/page.h
View File

@ -126,9 +126,12 @@ extern int page_is_ram(unsigned long pagenr);
#ifdef __ASSEMBLY__
#define __PAGE_OFFSET (0xC0000000)
#define __PHYSICAL_START CONFIG_PHYSICAL_START
#else
#define __PAGE_OFFSET (0xC0000000UL)
#define __PHYSICAL_START ((unsigned long)CONFIG_PHYSICAL_START)
#endif
#define __KERNEL_START (__PAGE_OFFSET + __PHYSICAL_START)
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)