[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: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 8 insertions, 6 deletions

diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S
index c5e80b69e7d4..b5893e4ecd37 100644
--- a/arch/i386/boot/compressed/head.S
+++ b/arch/i386/boot/compressed/head.S
@@ -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:
diff --git a/arch/i386/boot/compressed/misc.c b/arch/i386/boot/compressed/misc.c
index cedc55cc47de..e1330766965c 100644
--- a/arch/i386/boot/compressed/misc.c
+++ b/arch/i386/boot/compressed/misc.c
@@ -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;