From: Rob Landley <rob@landley.net>
Organization: Boundaries Unlimited
To: Neil Brown <neilb@suse.de>
Subject: Re: pivot_root broken in 2.6.15-rc1-mm2
Date: Wed, 23 Nov 2005 06:02:52 -0600
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On Tuesday 22 November 2005 21:01, Neil Brown wrote:
> Ah, OK.
> It's just that pivot_root works in this context in 2.6.11.9, so I
> figured it was a breakage.

And if you then umount the ramfs you just pivoted, the kernel locks hard.

That was a bug.

What you're looking for is switch_root, which has variants buried in klib, or 
in the current CVS version of busybox, or glued into Red Hat's weird little 
multi-function ramdisk shell, and probably a few other places by now.

Rather than unmounting rootfs, it deletes everything out of it to free up the 
space.  (It basically does the functional equivalent of "find / -xdev | xargs 
rm -rf", overmounts the old root with the new root, does a chroot, and execs 
the new init out of the new root.  Actually getting it right's a bit tricky, 
of course.  I still need to test the busybox version a whole lot more.  It's 
on my to-do list...)

Rob
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