I'm not sure it is <<Stream>> question but as the problem does appear only when trying amdbrook demos, I'm posting it here. Also, question to QA folks: there are so many people running Ubuntu on this forum, would you like to add ubuntu box to your testing fleet ?
I've bought a HD3870 (not X2) card to learn something about GPGPU and got into problems right after installing it. Finally I've got amdbrook/amdcal demos working after a bunch of workarounds but some are still crashing my system. floyd_warshall_d for example. Graphics itself seems to work well albeit I didn't test it extensively. Help. Details below:
My machine: Q6600+8GB RAM, PCI remap option turned on (not tested turning it off though - but I'll do it ASAP and post results). Gigabyte HD 3870 card.
Workaround 1: changed MTRR settings due to fglrx crashing my system right after starting X (problem with fglrx appearing machines with >= 3GB RAM):
# cat /proc/mtrr
reg00: base=0x00000000 ( 0MB), size=2048MB: write-back, count=1
reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
reg03: base=0x100000000 (4096MB), size=4096MB: write-back, count=1
reg04: base=0x200000000 (8192MB), size= 512MB: write-back, count=1
reg05: base=0x220000000 (8704MB), size= 256MB: write-back, count=1
Note that I've left a hole between 3328MB and 4096MB. I'm not sure what shall I put here. write-combining ? nocache ?
Workaround 2: # export LIBXCB_ALLOW_SLOPPY_LOCK=true
Workaround 3: removed splash from kernel boot parameters - to prevent switch from X to text crashing my machine;
Workaround 4: agp=off boot parameter (but I'm not sure it is needed anymore - it worked with my previous mobo where issue with PCI memory remapping caused panic during boot).