Linux, KMS, 3D, ATI, Oh My!

Yesterday I realized that accelerated 3D rendering no longer worked on my ancient ATI R200 based card. After some experimentation, I discovered that ATI accelerated 3D graphics now requires Kernel Mode Setting (KMS) to be enabled. This was a huge problem because Xv, the X accelerated video rendering system, has diagonal "lightning strike" tearing when used with KMS. I really wanted 3D back, though, so what to do?

Today, I was bored with work, so I decided to play with the ATI R600 based card which I bought way back in the spring. Initially it was very disappointing. The X server crashed almost immediately which was a regression from earlier tests: not a good sign!

Examining the system logs indicated that the problem appeared to be in the kernel, not the X server. I've been running a 2.6.34 kernel from Debian experimental and it so happens that a 2.6.36-rc6 kernel was available. Installing the newer version fixed the X server crash! Yay!

Accelerated 3D rendering now works on the R600 card but what about the tearing in Xv? Frankly, it was a bigger concern than 3D. If Xv didn't work, I would have to go back to the R200 card, which still supported an Xv mode that worked without KMS, and all this effort would have been for naught. So it was a great relief to discover that the Xv tearing problem has been fixed on the R600 card. Double Yay!

It's not often that one accomplishes anything while avoiding work, so I'm quite pleased with today's efforts. It's been a good day!

ATI 3D On Linux

According to this article, the open source 3D drivers for the older ATI R300-R500 graphics processors are much more mature than the newer generation R600/R700. I suspect that this indicates the age of the hardware that most developers own, but I could be wrong. I wish that I had known this before I bought an R600 based card. ^^

Not that it really matters, as cards using the earlier generation processors are quite difficult to find, unless you go the Ebay route. I'm still leery of buying electronics on Ebay. Call me paranoid...

Old And Slow

I started playing with with 3D modelling software (Blender, Wings 3D, and MakeHuman) and was graphically (pun intended) shown just how old and slow my ATI 9250 graphics card really is. The older GPU has are several problems which are individually tolerable, but, when taken together, you've basically hit a wall.

I'm shopping around for a replacement card. I have three basic constraints: I'm on a very tight budget, I want an ATI GPU, and it must be an AGP card. AGP?! Yup, I'm not replacing the motherboard yet (see constraint #1) so that's the way it has to be. An older design such as this ATI 3650 should be adequate.

Nvidia may offer better performance but that really only matters to serious gamers. Nvidia's closed source Linux drivers are actually very good, but since AMD released the programming documentation for ATI GPUs, the open source drivers for have been improving slowly but steadily. They are far from perfect yet but with proper documentation available, it's only a matter of time.