Patience

Although it is obvious to anyone who has tried to use the open source drivers for the AMD R600-based devices, these Phoronix benchmarks show just how bad things are. And those tests were performed with the most absolute blending edge pre-release versions of all the software involved. In other words, it going to be a long, long time before any improvements show up in a release version. Patience, have you must.

Xorg Radeon Status

For those keeping score, X.org has a table which describes the status of the major features in the radeon driver. Needless to say I'll be keeping a close eye on this page, looking for improvements in the R600, which is the GPU family used on 3650 cards.

There is an alternate driver, called radeonhd, but it appears to be slightly behind the radeon variant, especially for 3D features. I might try the radeonhd driver anyway, just for the heck of it. Hey, I have the hardware, so I might as well experiment.

Disabling Radeon KMS

Kernel Mode Setting (KMS) for the ATI Radeon RV280 chip is not ready for primetime yet so i decided to disable KMS and revert to User Mode Setting (UMS) for now. KMS is the future but it is too immature on the Radeon hardware. Now, how do I disable KMS?

First I changed /etc/modprobe.d/radeon-kms.conf to

option radeon modeset=0

Then I ran update-initramfs -u to copy the change into the boot RAM filesystem, and rebooted. For some reason that doesn't disable KMS. Hmm. Figure out why or find another way? Door number two please.

Next, I added the kernel parameter nomodeset in /boot/grub/menu.lst. Run update-grub and reboot. Nope. KMS is still enabled. Hmm. Figure out why or find another way? Door number two please.

Next I replaced the nomodeset kernel parameter with radeon.modeset=0, again in /boot/grub/menu.lst. Run update-grub and reboot. Ding ding ding, we have a winner! Phew! Pant, pant!

It should be abundantly clear that KMS in the Radeon driver is a work-in-progress when disabling it takes that much effort. ^_^