Upgrades, kernel removal and last-good-boot

Matt Zimmerman mdz at ubuntu.com
Fri Aug 15 15:56:13 BST 2008

On Fri, Aug 15, 2008 at 09:27:52AM -0400, Ben Collins wrote:
> On Fri, 2008-08-15 at 12:59 +0100, Matt Zimmerman wrote:
> > On Thu, Aug 14, 2008 at 04:50:17PM -0000, Michael Vogt wrote:
> > > Changes: 
> > >  apt (0.7.14ubuntu6) intrepid; urgency=low
> > >  .
> > >    * debian/apt.conf.autoremove:
> > >      - remove "linux-image" (and friends) from the auto-remove
> > >        blacklist. we have the kernel fallback infrastructure now
> > >        in intrepid (thanks to BenC)
> > 
> > Do we need to do anything further to ensure that this is safe for upgrades
> > from Hardy?  Will the system always have its old kernel saved in
> > last-good-boot before it's removed?
> For starters, removing the kernel from this exception doesn't mean it
> any will get automatically removed (from what I'm told).

You're correct for incremental upgrades, but if I'm not mistaken, the
release upgrader will explicitly clean up packages which are marked
automatic.  This may not take effect if it's using the Hardy version of apt,
though, since it still excludes kernels.

> Secondly, we've gone to great lengths to make sure that the system is
> never rebooted unless last-good-boot has been run. The only way that
> saving of the kernel would fail is if the system has a read-only root,
> from what I can tell (or runs out of inodes, since we only do
> hardlinks).
> I'm pretty confident in the setup, but maybe it would be worth adding to
> the QA to check that there is a last-good-boot entry on reboot, and try
> booting into it.

I looked at the spec, which says that the last-good-boot setup will be saved
by an init script in runlevel 2, but I couldn't find it.  Where does this
code live?

 - mdz

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