techblog 

One of my colleagues has already blogged about getting IRIS Explorer running on 64-bit Ubuntu 7.10.

A rather trickier problem that had to be solved first was getting X11 working reliably with the official NVidia drivers for his Quadro FX 3500 graphics card.

On first downloading and installing the drivers as per the NVidia instructions everything worked as expected. However on starting the machine up next morning X11 would only start in 800×600 resolution and wouldn’t run in Twinview (aka “Dual Head”) mode. At this point I was called in to help.

Installing the drivers again got X11 working again, but only until the next reboot. Looking at the list of loaded modules (with lsmod) I could see that an NVidia driver was loaded, but there was no explanation for why it wouldn’t work. Eventually, having run the driver installation process yet again again I noticed that according to lsmod the working driver appeared to be taking ~12MB of memory, whereas the non-working driver only used 8MB. Could it be that there were two different drivers?

I then verified (by looking at dmesg output) that there did indeed appear to be two different drivers - the non-working driver was actually being loaded into the kernel at boot-time, before any of the rest of the OS had been started. It seems that the boot image for starting the system has an NVidia driver built-in which is being used to support Ubuntu’s flashy boot screens!

I found that simply unloading the boot-time driver and loading the official driver (rmmod nvidia; modprobe nvidia) was sufficient to get X11 working again.

For now then, the work around is simple - in /etc/rc.local we’ve just put in:
/sbin/rmmod nvidia


This ensures that the boot-time driver is unloaded before any user programs are started. When X11 starts the module loader then automatically loads the correct driver and everything works as expected!