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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: klibc
Date: Fri, 9 Jun 2006 11:45:24 -0700 (PDT)
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Followup to:  <8764ja7o2d.fsf@hades.wkstn.nix>
By author:    Nix <nix@esperi.org.uk>
In newsgroup: linux.dev.kernel
> > 
> > You shouldn't pivot_root the rootfs filesystem.
> 
> What happens if you do? I mean, it doesn't make even conceptual sense,
> really. The rootfs is always there: that's its entire purpose.
> 

"What happens if you do"... well, it may work, it might not, it may
break some functionality for you or break in a future kernel version.
It's undefined behaviour.

> >                                                 Use the run-init
> > utility or something similar instead (which does a mount with
> > MS_MOVE.)
> 
> busybox has a switch_root tool which (conceptually) rm -rf's everything
> on the root filesystem and then does such a mount. (After all whatever
> is on that filesystem is inaccessible after the overmount, so keeping
> it around is just a waste of memory.)

What busybox calls switch_root is the same as the run-init tool from
the klibc distribution.

	-hpa