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Jean-Paul Saman c33df4eaaf [PATCH] disable init/initramfs.c

The file init/initramfs.c is always compiled and linked in the kernel
vmlinux even when BLK_DEV_RAM and BLK_DEV_INITRD are disabled and the
system isn't using any form of an initramfs or initrd.  In this situation
the code is only used to unpack a (static) default initial rootfilesystem.
The current init/initramfs.c code.  usr/initramfs_data.o compiles to a size
of ~15 kbytes.  Disabling BLK_DEV_RAM and BLK_DEV_INTRD shrinks the kernel
code size with ~60 Kbytes.

This patch avoids compiling in the code and data for initramfs support if
CONFIG_BLK_DEV_INITRD is not defined.  Instead of the initramfs code and
data it uses a small routine in init/noinitramfs.c to setup an initial
static default environment for mounting a rootfilesystem later on in the
kernel initialisation process.  The new code is: 164 bytes of size.

The patch is separated in two parts:
1) doesn't compile initramfs code when CONFIG_BLK_DEV_INITRD is not set
2) changing all plaforms vmlinux.lds.S files to not reserve an area of
PAGE_SIZE when CONFIG_BLK_DEV_INITRD is not set.

[deweerdt@free.fr: warning fix]
Signed-off-by: Jean-Paul Saman <jean-paul.saman@nxp.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2007-02-11 10:51:25 -08:00

1.8 KiB

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kbuild file for usr/ - including initramfs image

klibcdirs:; PHONY += klibcdirs

Generate builtin.o based on initramfs_data.o

obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o

initramfs_data.o contains the initramfs_data.cpio.gz image.

The image is included using .incbin, a dependency which is not

tracked automatically.

$(obj)/initramfs_data.o: $(obj)/initramfs_data.cpio.gz FORCE

Generate the initramfs cpio archive

hostprogs-y := gen_init_cpio initramfs := $(CONFIG_SHELL) $(srctree)/scripts/gen_initramfs_list.sh ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)),
$(shell echo $(CONFIG_INITRAMFS_SOURCE)),-d) ramfs-args :=
$(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID))
$(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID))

.initramfs_data.cpio.gz.d is used to identify all files included

in initramfs and to detect if any files are added/removed.

Removed files are identified by directory timestamp being updated

The dependency list is generated by gen_initramfs.sh -l

ifneq ($(wildcard $(obj)/.initramfs_data.cpio.gz.d),) include $(obj)/.initramfs_data.cpio.gz.d endif

quiet_cmd_initfs = GEN $@ cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)

targets := initramfs_data.cpio.gz

do not try to update files included in initramfs

$(deps_initramfs): ;

$(deps_initramfs): klibcdirs

We rebuild initramfs_data.cpio.gz if:

1) Any included file is newer then initramfs_data.cpio.gz

2) There are changes in which files are included (added or deleted)

3) If gen_init_cpio are newer than initramfs_data.cpio.gz

4) arguments to gen_initramfs.sh changes

$(obj)/initramfs_data.cpio.gz: $(obj)/gen_init_cpio $(deps_initramfs) klibcdirs $(Q)$(initramfs) -l $(ramfs-input) > $(obj)/.initramfs_data.cpio.gz.d $(call if_changed,initfs)

1.8 KiB Raw Blame History