Messages in this thread Patch in this message | | | Subject | [PATCH 1/2] disable init/initramfs.c (updated) | From | Jean-Paul Saman <> | Date | Thu, 14 Dec 2006 15:06:23 +0100 |
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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 makes it doesn't compile 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.
The patchset is compiled (2.6.10, 2.6.15, 2.6.git) and tested on mips (PNX8535, kernel version 2.6.10) and arm (IntegratorAP/ARM1176 SoC, kernel version 2.6.15).
Signed-off-by: Jean-Paul Saman <jean-paul.saman@nxp.com> ----------------------
Index: linux-2.6.git/drivers/block/Kconfig =================================================================== --- linux-2.6.git.orig/drivers/block/Kconfig 2006-12-14 13:21:54.000000000 +0100 +++ linux-2.6.git/drivers/block/Kconfig 2006-12-14 14:59:38.000000000 +0100 @@ -417,8 +417,10 @@ config BLK_DEV_INITRD etc. See <file:Documentation/initrd.txt> for details. If RAM disk support (BLK_DEV_RAM) is also included, this - also enables initial RAM disk (initrd) support. + also enables initial RAM disk (initrd) support and adds + 15 Kbytes (more on some other architectures) to the kernel size. + If unsure say Y. config CDROM_PKTCDVD tristate "Packet writing on CD/DVD media" Index: linux-2.6.git/init/Makefile =================================================================== --- linux-2.6.git.orig/init/Makefile 2006-12-14 13:21:54.000000000 +0100 +++ linux-2.6.git/init/Makefile 2006-12-14 14:00:49.000000000 +0100 @@ -2,7 +2,12 @@ # Makefile for the linux kernel. # -obj-y := main.o version.o mounts.o initramfs.o +obj-y := main.o version.o mounts.o +ifneq ($(CONFIG_BLK_DEV_INITRD),y) +obj-y += noinitramfs.o +else +obj-$(CONFIG_BLK_DEV_INITRD) += initramfs.o +endif obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o mounts-y := do_mounts.o Index: linux-2.6.git/usr/Makefile =================================================================== --- linux-2.6.git.orig/usr/Makefile 2006-12-14 13:21:54.000000000 +0100 +++ linux-2.6.git/usr/Makefile 2006-12-14 13:31:29.000000000 +0100 @@ -7,7 +7,7 @@ PHONY += klibcdirs # Generate builtin.o based on initramfs_data.o -obj-y := initramfs_data.o +obj-$(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 Index: linux-2.6.git/init/Kconfig =================================================================== --- linux-2.6.git.orig/init/Kconfig 2006-12-14 13:21:54.000000000 +0100 +++ linux-2.6.git/init/Kconfig 2006-12-14 13:38:44.000000000 +0100 @@ -280,8 +280,12 @@ config RELAY If unsure, say N. +if BLK_DEV_INITRD + source "usr/Kconfig" +endif + config CC_OPTIMIZE_FOR_SIZE bool "Optimize for size (Look out for broken compilers!)" default y Index: linux-2.6.git/init/noinitramfs.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6.git/init/noinitramfs.c 2006-12-14 13:31:29.000000000 +0100 @@ -0,0 +1,43 @@ +/* + * init/noinitramfs.c + * + * Copyright (C) 2006, NXP Semiconductors, All Rights Reserved + * Author: Jean-Paul Saman <jean-paul.saman@nxp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <linux/init.h> +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/fcntl.h> +#include <linux/delay.h> +#include <linux/string.h> +#include <linux/syscalls.h> + +/* + * Create a simple rootfs that is similar to the default initramfs + */ +static void __init default_rootfs(void) +{ + int mkdir_err = sys_mkdir("/dev", 0755); + int err = sys_mknod((const char __user *) "/dev/console", + S_IFCHR | S_IRUSR | S_IWUSR, + new_encode_dev(MKDEV(5, 1))); + if (err == -EROFS ) + printk( "Warning: Failed to create a rootfs\n" ); + mkdir_err = sys_mkdir("/root", 0700); +} +rootfs_initcall(default_rootfs); + --------------------------------- Kind greetings,
Jean-Paul Saman
NXP Semiconductors CTO/RTG DesignIP - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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