[ARM] 4736/1: Export atags to userspace and allow kexec to use customised atags

Currently, the atags used by kexec are fixed to the ones originally used
to boot the kernel. This is less than ideal as changing the commandline,
initrd and other options would be a useful feature.

This patch exports the atags used for the current kernel to userspace
through an "atags" file in procfs. The presence of the file is
controlled by its own Kconfig option and cleans up several ifdef blocks
into a separate file. The tags for the new kernel are assumed to be at
a fixed location before the kernel image itself. The location of the
tags used to boot the original kernel is unimportant and no longer
saved.

Based on a patch from Uli Luckas <u.luckas@road.de>

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Uli Luckas <u.luckas@road.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/asm-arm/kexec.h b/include/asm-arm/kexec.h
index 46dcc4d0b9bd..1ee17b6951d0 100644
--- a/include/asm-arm/kexec.h
+++ b/include/asm-arm/kexec.h
@@ -16,6 +16,9 @@
 
 #define KEXEC_BOOT_PARAMS_SIZE 1536
 
+#define KEXEC_ARM_ATAGS_OFFSET  0x1000
+#define KEXEC_ARM_ZIMAGE_OFFSET 0x8000
+
 #ifndef __ASSEMBLY__
 
 struct kimage;