For those not aware, some users are having an issue with the graphics driver for the N900. It started back in PR1.1, and while changes have been made to try to prevent the problem it's still occuring for some people in PR1.3. (I'm one of them, lucky me.)

It seems to be triggered by a combination of heavy graphics usage, high CPU usage, and possibly GPS usage, though the latter isn't always the case. Users that play intense flash games in the browser, or use high use programs like mapping programs (modRana, Mappero, etc) seem to see this more often. It's listed in bug tracker here. Feel free to vote for it.

My biggest issue with this is that it can happen just about any time, even when CPU use is low. The end result is a dead phone, as the process jumps silently to 98% CPU usage, burns through the battery, and the device shuts down, usually without a warning signal. Short of carrying a spare battery, you can't even turn it back on before charging it.

To help stop this until Nokia fixes it, I made a little script that checks to see if the process, a kernel level driver process in this case, is eating a lot of CPU. It only does this every 30 seconds or so, and is rather non-invasive. If it detects activity, it watches it a little closer, and issues warnings via espeak if things are going bad, then reboots. I did this just in case you're actively using it (on a call, etc). After a few warnings, it reboots the device, to prevent the system from draining the battery.

Currently there's no way to repair this other than rebooting. It would be great if there were a way to re-init the chipset/driver involved, but it's not a module from what I can see. If the custom kernel folks could compile this driver as a module, that would rock, since the script could then just re-init (or unload/reload) the graphics driver, and we could re-start X or what not, vs rebooting the whole device.

For now, this script handles the immediate issue of reaching into ones pocket and finding a dead device with no battery left. :P I placed it in /usr/sbin/ on my device and made an RC script to auto-start it at boot. It needs to be run as root to pull off the reboot, so keep that in mind. Hope this helps those having this issue frequently.

PS: The script assumes you have espeak installed. If you don't, you may want to install it, or replace the espeak lines with whatever notification mechanism you want to have. Or just delete those lines if you don't care about being warned.