nash, cpio and linuxrc

Féliciano Matias feliciano.matias at
Thu Feb 24 08:35:48 UTC 2005

Le mercredi 23 février 2005 à 17:07 +0100, Gildas Bayard a écrit :
> Hello,
> First of all, please direct me to an other mailing list if I'm going off
> topic.
> I've investigated a bit the initrd system and there are some questions I
> could no find answers for:
> - why are regular desktop distributions always using the initrd system?

It's require for "root=LABEL=/" and udev.

> I understand that this system is mandatory to load exotic scsi drivers
> or add a pause when booting to usb but I wonder why it is always used
> - on kernel 2.4 (red hat 9) the initrd image is an ext2 filesystems.

For *your* system. My initrd also contain raid0 and dm-mod
(see /sbin/mkinitrd and "man mkinitrd").

>  It
> contains a linuxrc nash script. On kernel 2.6 (fedora 3) the initrd is a
> cpio archive and does not contains a linuxrc script. Could someone
> briefly explain me why these differences? Particularly I wondering about
> 3 things:
> 1) I tried to repack my custom initrd ext2 filesystem into a cpio
> archive and found that when packed as a cpio archive it's not executing
> my linuxrc script (is it the way it's supposed to be?)

use "/init".

> 2) What are the differences between pivot_root and switch_root (new in
> 2.6) ?
> 3) Why using nash in the first place?

nash is a mini-mini-mini-shell (bash is TTOOOO big). See "man nash".

>  Could we just wait until the end
> of the linuxrc script? At that time the kernel would move to the new
> root fs (whitout the need for pivot_root or switch_root)
> And finally, if I'm right the end of the nash script (after switch_root)
> is never executed?
> Gildas
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