There's enough information out there now to get AFR Crossfire running on 5xx, although (see the Ask ATI Dev thread) we haven't yet documented the block that handles inter-chip compositing to accelerate modes like SFR and SuparAA. I just didn't want to slow down the rest of the 3d docs so haven't even looked at it.
The big issue with Crossfire (and SLI) is that they require a lot of software work to intelligently split the work across the GPUs. Putting the results back together is the easy part; we only use the special hardware on the high end boards anyways.
I would never have thought that there are written 100.000+ pages of specs for a GPU. It must be a strange feeling to have access to all this secret information!
You guys have the coolest job in the world!
We think soYou guys have the coolest job in the world!
When I talk to people who are not in the GPU business everyone is always amazed how big and complex the chips are -- almost 670 million transistors for an HD38xx and climbing. CPUs are typically smaller (a Phenom is ~460 million), and if you look at die shots much more of the CPU is cache memory than on a GPU. Even an RV610, which pretty much only has 1 of everything (2 4-way SIMD blocks, 1 quad texture, 1 quad ROP), is still almost 200 million transistors.
I have to admit that 100,000 is a guess -- I have never actually counted it all; I know that the one time I did start counting I got close to 10,000 pages pretty quickly and hadn't made a big dent in the documentation tree. A lot of it is auto-generated or in databases, so at least it doesn't all have to be typed in.I would never have thought that there are written 100.000+ pages of specs for a GPU.
Most of the time we get lucky and don't have to dig into the really detailed stuff, or we would need as many people to read it as it took to write it
The worst part is the "my head's gonna burst" feeling we get when starting on a new generation of GPUs. We're feeling it right now with the R6xxIt must be a strange feeling to have access to all this secret information!
Last edited by bridgman; 06-12-2008 at 08:13 PM.
I can't help but wonder how all the documentation is backed up
Do AMD have a Batman type of cave under the HQ with 1 meter concrete walls all around where the tapes and harddrive a stored and guarded doors looking like bank vaults?
The walls are so thick because there seems to be an underground river flowing through that spot -- when we dug the big hole for the new building the hole mostly filled up with water over the weekend. Backups are all offsite, which is probably good - if anything really bad happened to the data center, I wouldn't want the same thing to happen to our backup tapes
Last edited by bridgman; 06-14-2008 at 10:11 AM.