On Thu, Aug 30, 2012 at 03:15:17PM -0700, Eric W. Biederman wrote: > "Daniel P. Berrange" <berrange@xxxxxxxxxx> writes: > > > One of the features that SystemD folks have asked us to fix in LXC, is > > to make sure that /proc/sys/kernel/random/boot_id changes each time a > > container is started. > > There may be a good reason for this. Most of the time what I have seen > of kernel requests from the direction of SystemD is that while there may > be a real problem but usually their imagined solution is not a > particularly good solution. So a description of the problem is needed. > > Justifying something with just SystemD wants this is a good way to get > a nack. > > > The current semantics are that this file produces a new random UUID each > > time the host OS is booted. Obviously each time we start a container now, > > they just see the host's random boot_id, so from a container's POV this > > does not change each time it starts. > > That is correct. As I recall the contract with boot_id is to provide > a unique per boot value to assist in dealing with boots etc. I seem > to recall emacs uses the combination of hostname+boot_id to help > generate unique lock files names. > > I would definitely need a refresher on how boot_id is used in practice > by applications other than SystemD before I could suggest a good design. This post seems to describe what emacs wants boot_id for: http://marc.info/?l=linux-kernel&m=93613053109494&w=2 With this info, I think emacs inside a container would expect the boot_id to change each time the container is started, so they can detect stale locks from an emacs instance in a previous boot of the container. Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
