[PATCH] i386: Relocatable kernel support

This patch modifies the i386 kernel so that if CONFIG_RELOCATABLE is
selected it will be able to be loaded at any 4K aligned address below
1G.  The technique used is to compile the decompressor with -fPIC and
modify it so the decompressor is fully relocatable.  For the main
kernel relocations are generated.  Resulting in a kernel that is relocatable
with no runtime overhead and no need to modify the source code.

A reserved 32bit word in the parameters has been assigned
to serve as a stack so we figure out where are running.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 43 insertions, 0 deletions

diff --git a/arch/i386/boot/compressed/vmlinux.lds b/arch/i386/boot/compressed/vmlinux.lds
new file mode 100644
index 000000000000..cc4854f6c6c1
--- /dev/null
+++ b/arch/i386/boot/compressed/vmlinux.lds
@@ -0,0 +1,43 @@
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(startup_32)
+SECTIONS
+{
+        /* Be careful parts of head.S assume startup_32 is at
+         * address 0.
+         */
+        . =  0  ;
+        .text.head : {
+                _head = . ;
+                *(.text.head)
+                _ehead = . ;
+        }
+        .data.compressed : {
+                *(.data.compressed)
+        }
+        .text : {
+                _text = .;      /* Text */
+                *(.text)
+                *(.text.*)
+                _etext = . ;
+        }
+        .rodata : {
+                _rodata = . ;
+                *(.rodata)       /* read-only data */
+                *(.rodata.*)
+                _erodata = . ;
+        }
+        .data : {
+                _data = . ;
+                *(.data)
+                *(.data.*)
+                _edata = . ;
+        }
+        .bss : {
+                _bss = . ;
+                *(.bss)
+                *(.bss.*)
+                *(COMMON)
+                _end = . ;
+        }
+}