How to let INITRAMFS continue as root filesystem?

Hi,

I am using Linux kernel 2.6.15 on a MIPS embedded box. I am booting up
successfully using an initramfs compressed cpio archieve as my root,
but only after MANUALLY COMMENTING the call to prepare_namespace() in
init/main.c:init().

I referred to the following text in Documentation/early-userspace/README:

==========================================
c) using initramfs. The call to prepare_namespace() must be skipped.
This means that a binary must do all the work. Said binary can be stored
into initramfs <...snip...>. It must be called "/init". This binary
is responsible to do all the things prepare_namespace() would do.

<...snip...>, the /init binary will only run if it
comes via an initramfs cpio archive. If this is not the case,
init/main.c:init() will run prepare_namespace() to mount the final root
and exec one of the predefined init binaries.
==========================================

I understand that /init in initramfs is suuposed to mount the real
root, but in my case, I don't want to mount any other real root - I
just want the initramfs to remain the root.

1) Is there any command line option (like root=/dev/ram0 as in case of
initrd) to let the initramfs continue as the root file system?

2) The above README text suggests that the call to prepare_namespace()
will automatically be skipped if /init (in initramfs) mounts a real
root. Can somebody please point out in code how / where this is done?

Thanks,

Rajat
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Re: How to let INITRAMFS continue as root filesystem?

On 3/16/07, Rajat Jain wrote:
> Hi,
>
> I am using Linux kernel 2.6.15 on a MIPS embedded box. I am booting up
> successfully using an initramfs compressed cpio archieve as my root,
> but only after MANUALLY COMMENTING the call to prepare_namespace() in
> init/main.c:init().
>
> I referred to the following text in Documentation/early-userspace/README:
>
> ==========================================
> c) using initramfs. The call to prepare_namespace() must be skipped.
> This means that a binary must do all the work. Said binary can be stored
> into initramfs <...snip...>. It must be called "/init". This binary
> is responsible to do all the things prepare_namespace() would do.
>
> <...snip...>, the /init binary will only run if it
> comes via an initramfs cpio archive. If this is not the case,
> init/main.c:init() will run prepare_namespace() to mount the final root
> and exec one of the predefined init binaries.
> ==========================================
>
> I understand that /init in initramfs is suuposed to mount the real
> root, but in my case, I don't want to mount any other real root - I
> just want the initramfs to remain the root.
>
> 1) Is there any command line option (like root=/dev/ram0 as in case of
> initrd) to let the initramfs continue as the root file system?
>
> 2) The above README text suggests that the call to prepare_namespace()
> will automatically be skipped if /init (in initramfs) mounts a real
> root. Can somebody please point out in code how / where this is done?

OOPS ... found it! It was right there before my eyes ....its done int
init(). got the answer to my query no 2, however, my query 1 is still
open.

Thanks,

Rajat
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