Timer ISR/1: Time went backwards.

If you find yourself alone, riding through green fields with the sun on your face, do not be troubled. For you’re probably using an Intel-based system for virtualization, and are already dead!

Seriously, though, I’ve never had any of these weird goddamned problems with AMD-based systems. Well, whatever.

If you randomly get the ‘Timer ISR/1: Time went backwards’ bullshit, reboot your Dom0, enter BIOS, and make sure you turn off all of Intel’s power saving nonsense. For a Sun Fire x4150, specifically, kill the following crap:

Advanced > CPU Configuration > Intel(R) SpeedStep(tm) tech
Advanced > CPU Configuration > Intel(R) C-STATE tech

With an x4150, you may end up with a weird hardware clock issue – specifically, /dev/rtc being completely inaccessible. hwclock –debug will return errno=19.

If you’re already infuriated to the point of wanting to put a server through a wall, you can do the following:

Edit /etc/rc.sysinit and /etc/init.d/halt, comment out all lines referring to hwclock
Install and configure ntp
Edit /etc/sysconfig/ntpd, add the following to the first line of options: -x -g

-x will force ntpdate to run first on startup of ntpd, ensuring your eventual completely borked time will be set before ntpd proper starts. -g will ensure that ntpd can continue to mangle your time, even if somehow your drift is several days off the mark.

Would that Xen had a more up-to-date kernel, or that RedHat hadn’t abandoned it in favor of KVM. Or would that KVM was ready for prime time. :p