Upgrading and Downgrading

I haven’t posted for a while about my Scientific Linux 6.0 setup on my Thinkpad R60. It all kind of goes well. However SL 6.0 is kind of old, 6.1 has been out for a while and 6.2 is on the horizon (UPDATE: Ooops, I see its now out!). So I thought I’d upgrade to 6.1. But before jumping into the simple update process I thought I’d split my root mirror as a precaution. In recent years I just keep having problems with Linux Distro updates. Its not that the update process fails, it’s usually some oddball behaviour post upgrade that I can’t live with. Anyway, I do my mdadm fail and stop to detach one half of my boot and root mirrors and do the update to 6.1.

It all seemed to go well. I reboot … and it starts to boot but X windows does not start. I look at the Xorg log and there’s some Segmentation Fault without much detail, but I see its trying to access some dri stuff before the fault, and I know this dri stuff doesn’t exist when you have nomodeset set. See, I can’t get X to run reliably under SL 6.0 on my Thinkpad R60 without turning KMS off (I get lots of stupid flicker). Anyway, I think maybe this new kernel has fixed the flicker problem so I get rid of ‘nomodeset’ and reboot, and sure enough X now starts and looks kind of OK.

However leaving it on for a while the flickering starts to occur again, and then I start noticing these ‘kernel:Uhhuh. NMI received for unknown reason’ messages on my terminal sessions periodically. The system seems to still be going OK, but I do some research and find this centos page. So it’s not sounding like a good upgrade at this point; I can’t start X unless Kernel Mode Setting is set, and when I have Kernel Mode Setting set I can’t look at the screen because it flickers badly. Crazy!. So in less than an hour I’ve had enough pain and reverted my md mirrors back to SL 6.0.