[PATCH] i386: extend bzImage protocol for relocatable protected mode kernel

Extend bzImage protocol to enable bootloaders to load a completely relocatable
bzImage.  Now protected mode component of kernel is also relocatable and a
boot-loader can load the protected mode component at a differnt physical
address than 1MB.  (If kernel was built with CONFIG_RELOCATABLE)

Kexec can make use of it to load this kernel at a different physical address
to capture kernel crash dumps.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index c51314b1a463a35eb222d550409d0a29137149e2..cb28254f1550448474c6e78ad637fb2bd8fb2371 100644 (file)
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -35,6 +35,8 @@ Protocol 2.03:        (Kernel 2.4.18-pre1) Explicitly makes the highest possible
                initrd address available to the bootloader.
 
 Protocol 2.04: (Kernel 2.6.14) Extend the syssize field to four bytes.
+Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable.
+               Introduce relocatable_kernel and kernel_alignment fields.
 
 
 **** MEMORY LAYOUT
@@ -129,6 +131,8 @@ Offset      Proto   Name            Meaning
 0226/2 N/A     pad1            Unused
 0228/4 2.02+   cmd_line_ptr    32-bit pointer to the kernel command line
 022C/4 2.03+   initrd_addr_max Highest legal initrd address
+0230/4 2.04+   kernel_alignment Physical addr alignment required for kernel
+0234/1 2.04+   relocatable_kernel Whether kernel is relocatable or not
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.

diff --git a/arch/i386/boot/setup.S b/arch/i386/boot/setup.S
index 9aa8b05181842cbf3d341b322d2fbc258a0c0be3..06edf1c66242466e8853fcedd8afacc19228817a 100644 (file)
--- a/arch/i386/boot/setup.S
+++ b/arch/i386/boot/setup.S
@@ -81,7 +81,7 @@ start:
 # This is the setup header, and it must start at %cs:2 (old 0x9020:2)
 
                .ascii  "HdrS"          # header signature
-               .word   0x0204          # header version number (>= 0x0105)
+               .word   0x0205          # header version number (>= 0x0105)
                                        # or else old loadlin-1.5 will fail)
 realmode_swtch:        .word   0, 0            # default_switch, SETUPSEG
 start_sys_seg: .word   SYSSEG
@@ -160,6 +160,17 @@ ramdisk_max:       .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
                                        # The highest safe address for
                                        # the contents of an initrd
 
+kernel_alignment:  .long CONFIG_PHYSICAL_ALIGN         #physical addr alignment
+                                               #required for protected mode
+                                               #kernel
+#ifdef CONFIG_RELOCATABLE
+relocatable_kernel:    .byte 1
+#else
+relocatable_kernel:    .byte 0
+#endif
+pad2:                  .byte 0
+pad3:                  .word 0
+
 trampoline:    call    start_of_setup
                .align 16
                                        # The offset at this point is 0x240