[PATCH] initramfs: unprivileged image creation

[PATCH] initramfs: unprivileged image creation

This patch makes several tweaks so that an initramfs image can be
completely created by an unprivileged user.  It should maintain
compatibility with previous initramfs early userspace cpio/image creation
and it updates documentation.

There are a few very important tweaks:

CONFIG_INITRAMFS_SOURCE is now either a single cpio archive that is
directly used or a list of directories and files for building a cpio
archive for the initramfs image.  Making the cpio archive listable in
CONFIG_INITRAMFS_SOURCE makes the cpio step more official and automated so
that it doesn't have to be copied by hand to usr/initramfs_data.cpio (I
think this was broken anyway and would be overwritten).  The alternative
list of directories *and* files means that files can be install in a "root"
directory and device-special files can be listed in a file list.

CONFIG_ROOT_UID and CONFIG_ROOT_GID are now available for doing simple
user/group ID translation.  That means that user ID 500, group ID 500 can
create all the files in the "root" directory, but that they can all be
owned by user ID 0, group ID 0 in the cpio image.

Various documentation updates to pull it all together.

Removal of old cruft that was unused/misleading.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>