[PATCH] kexec: x86_64: add CONFIG_PHYSICAL_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_64 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>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h
index 60130f4ca986..431318764af6 100644
--- a/include/asm-x86_64/page.h
+++ b/include/asm-x86_64/page.h
@@ -64,12 +64,14 @@ typedef struct { unsigned long pgprot; } pgprot_t;
 #define __pgd(x) ((pgd_t) { (x) } )
 #define __pgprot(x)     ((pgprot_t) { (x) } )
 
-#define __START_KERNEL          0xffffffff80100000UL
+#define __PHYSICAL_START        ((unsigned long)CONFIG_PHYSICAL_START)
+#define __START_KERNEL          (__START_KERNEL_map + __PHYSICAL_START)
 #define __START_KERNEL_map      0xffffffff80000000UL
 #define __PAGE_OFFSET           0xffff810000000000UL
 
 #else
-#define __START_KERNEL          0xffffffff80100000
+#define __PHYSICAL_START        CONFIG_PHYSICAL_START
+#define __START_KERNEL          (__START_KERNEL_map + __PHYSICAL_START)
 #define __START_KERNEL_map      0xffffffff80000000
 #define __PAGE_OFFSET           0xffff810000000000
 #endif /* !__ASSEMBLY__ */