can't switch_root

[Baruch Siach]

Hi Dutta,

On Tue, Oct 04, 2011 at 02:12:35PM +0530, Dutta, Kanishka wrote:
> Thanks for your inputs. I tried with exec switch_root /newroot /sbin/init 
> (as you suggested, but getting this issue:-
> 
> # exec switch_root /newroot /sbin/init
> udevd[108]: specified group 'dialout' unknown
> udevd[108]: specified group 'disk' unknown
> udevd[108]: specified group 'tty' unknown
> udevd[108]: specified group 'kmem' unknown
> udevd[108]: specified group 'video' unknown
> udevd[108]: specified group 'audio' unknown
> udevd[108]: specified group 'lp' unknown
> udevd[108]: specified group 'floppy' unknown
> udevd[108]: specified group 'cdrom' unknown
> udevd[108]: specified group 'tape' unknown
> Usage: init 0123udevd[108]: specified group 'plugdev' unknown
> udevd[108]: specified group 'users' unknown

The switch_root thing then seems to be working.

> After this the console hangs and I am unable to get any kernel prompt beyond 
> this point.

The most likely reason is that you don't have getty running on your console. 
Check your /etc/inittab.

Note that since this has nothing to do with Busybox, and is off topic here.

baruch

> ________________________________________
> From: Baruch Siach [baruch at tkos.co.il]
> Sent: Monday, October 03, 2011 9:19 PM
> To: Dutta, Kanishka
> Cc: Laurent Bercot; busybox at busybox.net
> Subject: Re: can't switch_root
> 
> Hi Dutta,
> 
> On Mon, Oct 03, 2011 at 08:17:42PM +0530, Dutta, Kanishka wrote:
> > When the system boots up, I am creating a new dir and mounting the separate partition on top of this
> > # mkdir newroot
> > # mount dev/mmcblk0p14 newroot
> >
> > whole of system partition gets mounted on newroot successfully, after that, I give the command for switch_root :-
> >
> > # switch_root newroot sbin/init
> > switch_root: failed to mount moving /dev to newroot/dev: Invalid argument
> > switch_root: forcing unmount of /dev
> > switch_root: failed to mount moving /proc to newroot/proc: Invalid argument
> > switch_root: forcing unmount of /proc
> > switch_root: failed to mount moving /sys to newroot/sys: Invalid argument
> > switch_root: forcing unmount of /sys
> > switch_root: failed to mount moving newroot to /: No such file or directory
> > switch_root: failed. Sorry.
> 
> You seem to be running the util-linux version of switch_root, not the Busybox
> one. In any case, give the absolute path in 'newroot', that is '/newroot',
> relative path won't work. See the source for why. Also, you should do
> 
> # exec switch_root /newroot /sbin/init
> 
> because you need to run the new /sbin/init as PID 1. This assumes that your
> shell is actually PID 1. If not, this won't work.
> 
> baruch
> 
> > ________________________________________
> > From: Laurent Bercot [ska-dietlibc at skarnet.org]
> > Sent: Monday, October 03, 2011 8:18 PM
> > To: busybox at busybox.net
> > Cc: Dutta, Kanishka
> > Subject: Re: can't switch_root
> >
> > > Yes, initially I am booting up with minimal initramfs.
> >
> >  Well in that case you cannot use pivot_root, and have to use switch_root
> > indeed.
> >  (You could also clean up your filesystem by hand and then mount --move,
> > but that offers no real benefit over using switch_root, which does exactly
> > that for you.)
> >
> >  Could you send the output of a strace of your switch_root command ?

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -