[Bug 1075717] Re: mounted-dev must not re-create consoles in a container

[Steve Langasek]

Have talked through this with hallyn in detail.

 - we don't want to change MAKEDEV itself to not clobber existing device nodes, because in other cases this makes recovery from broken /dev less reliable
 - we can't side-step this by making /dev not be a mountpoint within the container because in some cases users want to use a read-only rootfs
 - we can't use devtmpfs instead because there is only *one* devtmpfs in the kernel no matter where it's mounted, so this would make it impossible to make the exact change to node targets that this is about.

So I'm convinced that the linked branch is an appropriate solution to
this problem.  It has no impact on the common case when /dev is a
devtmpfs, we don't call MAKEDEV at all in that scenario.

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https://bugs.launchpad.net/bugs/1075717

Title:
  mounted-dev must not re-create consoles in a container

Status in “lxc” package in Ubuntu:
  Triaged
Status in “mountall” package in Ubuntu:
  Triaged

Bug description:
  mounted-dev.conf always does MAKEDEV console.  MAKEDEV doesn't just
  make the devices, it first removes them.

  When a container starts, it sets up /dev/console and /dev/lxc[1-4] as
  bind mounts of ptys on the host, for use as lxc consoles.  If mounted-
  dev deletes and recreates those, then none of the lxc consoles work.

  A simple patch which stops it from breaking lxc consoles is at lp
  :~serge-hallyn/ubuntu/quantal/mountall/mountall-lxc .  However looking
  back at it, I think it would be ok to do a further check for whether
  /dev/console exists.  If it does not exist, then MAKEDEV console
  anyway.  This isn't necessary, just a thought.

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