Commit 3d345e3f authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
Browse files

[PATCH] kexec: x86: add CONFIG_PYSICAL_START 



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: default avatarEric Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5ded01e8

arch/i386/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -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

arch/i386/boot/compressed/head.S

+4 −3
Original line number Diff line number Diff line
@@ -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:

arch/i386/boot/compressed/misc.c

+4 −3
Original line number Diff line number Diff line
@@ -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;

arch/i386/kernel/vmlinux.lds.S

+1 −1
Original line number Diff line number Diff line
@@ -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 */

include/asm-i386/page.h

+3 −0
Original line number Diff line number Diff line
@@ -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)