Comment 43 for bug 428435

If we want to concentrate on the "real problem", like David put it, then we should look at udev. Udev is responsible of creating the /dev/disks/by-uuid/ entries and it uses blkid to do so. Missing entries cause the boot to fail with fully encrypted hard drives and udev is the first failing step on automatic handling of other encrypted partitions, too.

Here's what I propose:

1. Create a help.ubuntu.com page
This page should document the problem in detail and give affected people instructions how to fix it. As many people as possible should also blog about it (planet.ubuntu.com) to get google ratings high enough so that affected users find the page.

This page can easily be up until and beyond April 2013.

2. patch udev
Udev should notify that there's multiple signatures on newly available partition. We can then notify the user in appropriate way for the current environment (see below) .

3. inform the user

There are basically three types of environments where this bug occurs:
   a) desktop users with encrypted removable media
   b) full disk encryption during boot
   c) others

a) is the easiest to fix. When user inserts an encrypted USB stick or such during normal desktop session udev notifies that there's multiple signatures and can't go on. We pop up a window to inform the user of the situation and give the link to the friendly help.ubuntu.com page.

For long term solution you can create a nice graphical helper program and launch it here automatically. For karmic's release I don't see there's enough time to do this.

b) is harder as the bug happens on initrd environment which does only contain the bare minimum to access the root partition. At this point there's nothing more we can do other than inform the user on splash screen output and give the link to the help.ubuntu.com page which has specific instructions how to fix the problem on upgraded machine with unaccessible root partition.

Long term solution is to have update manager to check the signature of root partition before upgrading.

c) contains all the other kind of installation, like console only and etc. Just make sure udev or what ever print outs a big informational warning to syslog which gives the link to the help page. Also make sure release notes for upcoming releases contain a warning about the situation. Administrators of critical systems probably read the release notes and thus know what to expect and maybe even fix the signatures before doing the upgrade. And if they don't then they at least should check the syslog when they notice stuff doesn't work how it's meant to.