I love doing stupid things. No, really, I mean that with all my heart. Every time I do something stupid and manage to recover from it without too much pain, I feel as if some part of my mandatory universal stupidity quota has just been filled. My normal sense of complacency is repealed, I pay better attention to all the buttons I normally push without thinking, and I become hyper-vigilant to avoid doing anything glaringly dumb. For a while.
The latest stupid thing I did happened while upgrading to Ubuntu Feisty. Actually, I upgraded several hosts without a hitch, so really, power to the people at Ubuntu for making such clean upgrade paths (and, I suppose, to the Debian folks for the underlying package manager on which it all depends). Unfortunately, when I pulled the big handle on my primary server and X11 platform, I wasn't paying enough attention. The upgrade rolled around just fine, updating old packages and removing obsolete ones, while I blindly agreed to every prompt that popped up.
The time to restart comes along and... oh, what's this? What do you mean you can't find a kernel?
It's not fair to say that it couldn't find the kernel, exactly. The kernel loaded just fine. Unfortunately the kernel is a Xen Hypervisor, which points to another kernel to use for the Dom0 machine instance which runs my actual server. And that kernel was nowhere to be found. After a bit of digging it became painfully obvious that one of the obsolete packages I had blindly thrown out was, in fact, my precompiled Xen generic x86 kernel.
Thankfully I have lots of other internet connected machines at my disposal, and it was a quick matter to grab an Ubuntu Live-CD and boot into a root shell on my server from there. Another few minutes of fiddling and I had apt-get'ted myself the latest Xen generic x86 kernel package. One last smidgen of editing in the GRUB list, and all was well once again.
So other than my heart skipping a beat or ten, this was happily a very painless act of stupidity. At my current quota-filling rate, I expect I'll be posting something eerily similar to this in, oh, another 5 months or so. I can only hope it'll be as easy to fix as this one was.