[lxc-devel] Why pivot_root()?

[Ludovic Guégan]

Hi Rob,

It was discussed here:
http://www.redhat.com/archives/libvir-list/2009-April/msg00116.html

Ludo

On Sun, Apr 24, 2011 at 6:46 AM, Rob Landley <rlandley at parallels.com> wrote:

> I'm reading through the LXC code and for some reason it's using
> pivot_root() instead of chroot().  Is there a reason for this?  (We need
> to iterate through every process in the system and make sure that kernel
> threads that are the children of the host's PID 1 get evicted from the
> old mount point so we can umount it?  But the host context isn't going
> away when we launch a container...)
>
> I thought that syscall was created to dispose of initrd so the system
> could free the ramdisk block device without the kernel threads that were
> reparented to init pinning the mount point, and one of the big
> advantages of initramfs is it _didn't_ need to call that particular
> piece of black magic (because initramfs provides a low-overhead place to
> park daemonized kernel threads).
>
> What's the advantage of using it here?
>
> Rob
>
>
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