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Date: Wed, 13 Dec 2006 13:50:57 +0300
From: Al Boldi <a1426z@...ab.com>
To: Jean-Paul Saman <jean-paul.saman@....com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: Fw: RFC [PATCH] 1/2 disable initramfs
Jean-Paul Saman wrote:
> Al,
>
> Thank you for reviewing my other patch and telling me it was wrong. I am
> working for an embedded HW manufacturer doing linux kernel ports to their
> arm platforms. In an attempt to minimize the amount of code that needs to
> be loaded from flash in an embedded system I identified 60 Kbytes of code
> (init/initramfs.c) that was not used in our products. So I would like to
> add an option to the kernel to disable the use of initrd/initramfs when it
> isn't used at all. Saving 60Kbytes of code in memory and on flashdisk.
Good idea.
> Are you the one I should ask to review it?
Not really.
> Or can you suggest someone else?
Last time I worked on initramfs, it was hpa who shot it down, even though it
was correct code-wise.
Maybe try to CC him <hpa@...or.com>, and Andrew <akpm@...l.org> as well.
Thanks for keeping on trying.
--
Al
> Kind greetings,
>
> Jean-Paul Saman
>
> NXP Semiconductors CTO/RTG DesignIP
>
> ----- Forwarded by Jean-Paul Saman/EHV/SC/PHILIPS on 13-12-2006 09:40
> -----
>
> linux-kernel-owner@...r.kernel.org wrote on 06-12-2006 17:39:48:
> > 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 init/initramfs.c code compiles to a size of 60 kbytes.
> >
> > This patch makes it configurable (CONFIG_BLK_DEV_INITRAMFS) to disable
>
> the
>
> > use of a initramfs (60 kbytes of code). Instead of the init/initramfs.c
> > code it uses a small routine in init/main.c to setup an initial static
> > environment for mounting a rootfilesystem later on in the kernel
> > initialisation process.
> >
> > Signed-off-by: Jean-Paul Saman <jean-paul.saman@....com>
> >
> > Index: linux-2.6.git/drivers/block/Kconfig
> > ===================================================================
> > --- linux-2.6.git.orig/drivers/block/Kconfig 2006-12-06
> > 15:27:51.000000000 +0100
> > +++ linux-2.6.git/drivers/block/Kconfig 2006-12-06 16:35:40.000000000
> > +0100
> > @@ -411,19 +411,32 @@ config BLK_DEV_RAM_BLOCKSIZE
> > setups function - apparently needed by the rd_load_image
>
> routine
>
> > that supposes the filesystem in the image uses a 1024
>
> blocksize.
>
> > +config BLK_DEV_INITRAMFS
> > + bool "Enable RAM filesystem (initramfs) support"
> > + default y
> > + help
> > + The initial RAM filesystem is a ramfs filesystem which can be
> > + linked in the kernel and that is mounted as root before the
> > normal
> > + boot procedure. It is typically used to load modules needed to
> >
> > mount
> > + the "real" root file system, etc. See
> > <file:Documentation/initrd.txt>
> > + for details.
> > +
> > + Enabling BLK_DEV_RAM and BLK_DEV_INITRD adds 60 kbytes size to
> >
> > your kernel.
> > +
> > + If unsure say Y.
> > +
> > config BLK_DEV_INITRD
> > - bool "Initial RAM filesystem and RAM disk (initramfs/initrd)
> > support"
> > - depends on BROKEN || !FRV
> > + bool "Check for Initial RAM disk (initrd/initramfs) on kernel
> > boot"
> > + depends on BLK_DEV_INITRAMFS && ( BROKEN || !FRV )
> > help
> > - The initial RAM filesystem is a ramfs which is loaded by the
> > + The initial RAM disk is a ramfs filesystem which is loaded by
> > the
> > boot loader (loadlin or lilo) and that is mounted as root
> > before the normal boot procedure. It is typically used to
> > load modules needed to mount the "real" root file system,
> > 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 enable initial RAM filesystem disk support as initrd.
> >
> > config CDROM_PKTCDVD
> > tristate "Packet writing on CD/DVD media"
> > Index: linux-2.6.git/init/Makefile
> > ===================================================================
> > --- linux-2.6.git.orig/init/Makefile 2006-12-06 15:27:51.000000000
> > +0100
> > +++ linux-2.6.git/init/Makefile 2006-12-06 15:27:54.000000000 +0100
> > @@ -2,7 +2,8 @@
> > # Makefile for the linux kernel.
> > #
> >
> > -obj-y := main.o version.o mounts.o initramfs.o
> > +obj-y := main.o version.o mounts.o
> > +obj-$(CONFIG_BLK_DEV_INITRAMFS) := initramfs.o
> > obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
> >
> > mounts-y := do_mounts.o
> > Index: linux-2.6.git/init/main.c
> > ===================================================================
> > --- linux-2.6.git.orig/init/main.c 2006-12-06 15:27:51.000000000
> > +0100
> > +++ linux-2.6.git/init/main.c 2006-12-06 15:27:54.000000000 +0100
> > @@ -86,7 +86,9 @@ extern void pidmap_init(void);
> > extern void prio_tree_init(void);
> > extern void radix_tree_init(void);
> > extern void free_initmem(void);
> > +#ifdef CONFIG_BLK_DEV_INITRAMFS
> > extern void populate_rootfs(void);
> > +#endif
> > extern void driver_init(void);
> > extern void prepare_namespace(void);
> > #ifdef CONFIG_ACPI
> > @@ -705,6 +707,22 @@ static void run_init_process(char *init_
> > kernel_execve(init_filename, argv_init, envp_init);
> > }
> >
> > +#ifndef CONFIG_BLK_DEV_INITRAMFS
> > +/*
> > + * Create a simple rootfs that is similar to the default initramfs
> > + */
> > +static void populate_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);
> > +}
> > +#endif
> > +
> > static int init(void * unused)
> > {
> > lock_kernel();
> > @@ -741,6 +759,7 @@ static int init(void * unused)
> >
> > do_basic_setup();
> >
> > +#ifdef CONFIG_BLK_DEV_INITRAMFS
> > /*
> > * check if there is an early userspace init. If yes, let it do
> >
> > all
> > * the work
> > @@ -753,7 +772,10 @@ static int init(void * unused)
> > ramdisk_execute_command = NULL;
> > prepare_namespace();
> > }
> > -
> > +#else
> > + ramdisk_execute_command = NULL;
> > + prepare_namespace();
> > +#endif
> > /*
> > * Ok, we have completed the initial bootup, and
> > * we're essentially up and running. Get rid of the
> > Index: linux-2.6.git/usr/Makefile
> > ===================================================================
> > --- linux-2.6.git.orig/usr/Makefile 2006-12-06 15:27:51.000000000
> > +0100
> > +++ linux-2.6.git/usr/Makefile 2006-12-06 15:27:54.000000000 +0100
> > @@ -7,7 +7,7 @@ PHONY += klibcdirs
> >
> >
> > # Generate builtin.o based on initramfs_data.o
> > -obj-y := initramfs_data.o
> > +obj-$(CONFIG_BLK_DEV_INITRAMFS) := 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 2006-12-06 15:27:51.000000000
> > +0100
> > +++ linux-2.6.git/init/Kconfig 2006-12-06 15:27:54.000000000 +0100
> > @@ -280,8 +280,12 @@ config RELAY
> >
> > If unsure, say N.
> >
> > +if CONFIG_BLK_DEV_INITRAMFS
> > +
> > source "usr/Kconfig"
> >
> > +endif
> > +
> > config CC_OPTIMIZE_FOR_SIZE
> > bool "Optimize for size (Look out for broken compilers!)"
> > default y
> >
> > --------
> > Kind greetings,
> >
> > Jean-Paul Saman
> >
> > NXP Semiconductors CTO/RTG DesignIP
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
>
> in
>
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