[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, 7 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 4b1a8e3d292c..4bd8952eef9a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -894,6 +894,13 @@ config KEXEC
           initially work for you.  It may help to enable device hotplugging
           support.
 
+config ATAGS_PROC
+        bool "Export atags in procfs"
+        default n
+        help
+          Should the atags used to boot the kernel be exported in an "atags"
+          file in procfs. Useful with kexec.
+
 endmenu
 
 if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX || ARCH_PXA)