Re: [gentoo-user] Help with ramdisk

[Richard Fish <bigfish@asmallpond.org>]

Is this an initrd or initramfs (aka, cpio.gz) image?

If it is initrd, you should have a /linuxrc script to initialize the 
system.  For grub, you will need:

	kernel /vmlinuz root=/dev/ram0 init=/linuxrc
	initrd=/rootfs.gz

Then your linuxrc script must *not* exit.  It will probably need to call 
/sbin/init with something like:

    exec /sbin/init $@

In your case, /linuxrc probably doesn't need to do much of anything else.


If it is initrams, then you just need to create a /init script and place 
the same "exec /sbin/init..." inside it.  You do not need the init= 
option for the kernel in the grub configuration.

For some more info, take a look at 
/usr/src/linux/Documentation/early-userspace/README

HTH

-Richard

Ognjen Bezanov wrote:

>Hi all,
>
>Im building an x86 embedded distro using gentoo. Now i have been rather
>successful. I have built the whole system and it works, while only
>taking up 9mb (when gzipped).
>
>Now my question is how to get linux to load the gzipped image file into
>a ramdisk and use it as a root filesystem.
>
>Running the system directly from the CF card works great, but when
>trying to get it to run it in ram it fails
>with "kernel panic: VFS: Unable to mount root fs on unknown-block(1,0)".
>
>My attempt at running the system from ram is as follows:
>
>(grub config file):
>
>kernel /vmlinuz    initrd=/rootfs.gz   root=/dev/ram0
>
>the rootfs.gz file is ~10Mb, and when uncompressed is an 100mb image
>(most of the image is free space to
>allow for future additions, this is a test bed).
>
>
>Now I presume this is probably what is incorrect, in which case can
>anyone help me regarding how to use
>ramdisks as root devices. (googling about tells me that the initrd image
>is not the root image, but rather
>a pre-root mounting fs to prepare the system for booting).
>
>P.S Please CC me as this mailinglist doesnt play nice with my email
>account. thanks!
>
>  
>
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