AnsweredAssumed Answered

GDS memory revisited, moving from Tahiti to Hawaii

Question asked by drallan on Apr 1, 2015
Latest reply on Jan 22, 2017 by meriken

Ah, it's good to be back and see familiar names.


Question background

I have been developing programs using GCN at the assembly level including frequent use of the gds memory.

I use a basic, but not so simple method that others here have used in the past.

  1. develop an assembler/compiler tool to generate the desired GCN binary.

  2. Use OpenCL to compile a simple shell program that uses the same or similar buffers/resources.

  3. Open and unwrap the OpenCL elf binary file and replace the executable code with mine. 

   (this requires some fixups to make the new and old binary environments compatible)

  4. Allow OpenCL to run the program.


This has been working fine for about a year using a 3X 7970 Tahiti system.

Then I blew one of the Tahiti cards and replaced it with a Hawaii R9 290X.

I have now updated all drivers and Opencl successfully and all runs as before,


The Hawaii 290X card cannot read the gds memory.

This seems odd because the 7970s and 290X are running identical code side by side in parallel.

The 7970s can read/write gds as before.

I have searched extensively for differences between the two OpenCL programs and see nothing obvious.

OpenCL is generating 3 binaries for Tahiti, Tahiti, and Hawaii (called Hawks in the binary file)

I am careful to make sure the OpenCL shell program for Hawaii goes to the R9 290X card.


The only thing I can think of is that GCN 1.1 requires a hardware setting to activate the gds that was not in GCN 1.0


Any clues about how Hawaii is different from Tahiti would be greatly appreciated.

Pointers to any relevant documentation would be wonderful.


If anyone is interested in our work, please see

We are developing ultra fast DNA processing for genetics and achieve about a 100X speedup

over other tools even ones using nvidia gpus.

Our claim is this speedup is from AMD GCN! (If only I can get gds working again    )


Many thanks.


Some previous threads on gds memory for reference.