[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>

diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 961ab20032f5b18a51a14b5ad34922760cf83cb3..31567f4d333a47af47cbfcf4e67cb5a7b71abd5e 100644 (file)
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -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
 
 

diff --git a/arch/i386/boot/compressed/head.S b/arch/i386/boot/compressed/head.S
index c5e80b69e7d41d8ae580ae734553d2b9584b9760..b5893e4ecd376b54a3044c09e035ff82bf5e923c 100644 (file)
--- 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 cedc55cc47de0756df6e77afc0e94fedba2439f5..e1330766965c5c64f8e6dbcaac94181a2307ed3b 100644 (file)
--- 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;

diff --git a/arch/i386/kernel/vmlinux.lds.S b/arch/i386/kernel/vmlinux.lds.S
index e17ab69c1f0563d9a8a1cfa593e0a4ac1e526abf..7e01a528a83a168f86214907103d7bbe1f2e964d 100644 (file)
--- a/arch/i386/kernel/vmlinux.lds.S
+++ b/arch/i386/kernel/vmlinux.lds.S
@@ -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 */

diff --git a/include/asm-i386/page.h b/include/asm-i386/page.h
index dea8f8e6d86ed60dc5bcfdafd324fd16f9c421ef..8d93f732d72d0586dc1598542ffa354893351808 100644 (file)
--- a/include/asm-i386/page.h
+++ b/include/asm-i386/page.h
@@ -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)