Re: Fw: RFC [PATCH] 1/2 disable initramfs

[Al Boldi <a1426z@gawab.com>]

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@zytor.com>, and Andrew <akpm@osdl.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@vger.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@nxp.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"
>
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>
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