nash, cpio and linuxrc

[Féliciano Matias]

Le jeudi 24 février 2005 à 10:13 +0100, Gildas Bayard a écrit :
> Le jeudi 24 février 2005 à 09:35 +0100, Féliciano Matias a écrit :
> > Le mercredi 23 février 2005 à 17:07 +0100, Gildas Bayard a écrit :
> > > 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").
> No I mean the initrd file is an ext2 filesystem (whatever it contains)
> On FC3 it is a cpio archive. Why?

Not sure, but I think because cpio archive is smaller.

>  And why when initrd is a cpio archive
> it would not load linuxrc?

I don't know.

> Answers to these question are not in man initrd, man nash...
> > 
> > >  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".
> Well I want to understand why my linuxrc is not run when in a cpio
> archive and again what the matter with the cpio archive
> > 
> > > 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".
> man nash does not explain what is the rational for both pivot_root and
> switch_root (just give a small description).
> => Why pivot_root was not enough?

From rom nash.c :
        /* 2.6 magic not-pivot-root but kind of similar stuff.
         * This is based on code from klibc/utils/run_init.c
         */
        int switchrootCommand(char * cmd, char * end) {

> => Why not wait until the end of linuxrc to jump to the new root fs?
> 

???

> I would like to know how to get in touch with nash coders.

From rom nash.c :
 * Erik Troan (ewt _AT_ redhat.com)
 * Jeremy Katz (katzj _AT_ redhat.com)


>  On which
> forum or mailing list could they be hanging on?

fedora-devel :-)

> > >  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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