well, i bougth a 4850x2 in amazon (i was still happy then, i was young and naive too) so i proceed first with win7 rc1 (same vista crap with some bugifxes so far)only to test some new games like farcry2, and it was so nice this card power XD so i proceed later that nigth to my jaunty install and remove all nvidia drivers (now i slap myself everytime i have something bad to say about those god blessed drivers )and installed fglrx (big mistake btw) in resume everything is crappy/choppy/slow so i almost kill myself (damn 330$ and dont work in linux)so before RMA to get a 285 gtx, i decided to give a try with radeon driver(and put the gun back in to my desk). so my experince so far isbtw im a c++ dev any normal user would RMA instantly or shoot himself, but as as geek i decide the git path)
*after experience a bit of procedure first
-install kubuntu karmic koala rc2 + full update
-add radeon crack ppa to your installation, only to forget about mesa git compilation and get kms kernel
-then make a git clone to the latest snap of radeon driver, the one with radeon crack dont work because this card have the wrong PCIid in the driver. after the git clone go to PCIid file and add 0x9443 to 4850x2 list
-the same bad PCIid is in drm too
so this part im working on it cuz git drm fixes it the same way just changing the PCIid buuuuuuuut the ttm.ko dont load cuz of undefined symbols so i need a 2.6.31 staging kernel backport wich is still wip so far maybe today i got it modprobing
1.)2D performance: i managed to get a nicely EXA ligth speed fast(still waiting for some patching )dual desktop configuration, yes no crossfire X but 2 monitors each one rendered by a 4850 is very nice too, and yes no glitches so far, mmm i reminded me the nice Xi Graphics Ati driver
2.) DRI: i have big hopes cuz software renderer is slow but it work very stable and it doesnt complain about anything + 4850 is supported so im very optimistic and only complain is wrong PCIid
3.) Video: only need DRI to activate but even disabled video work quite well so i think DRI will only improve it
4.) MultiHead: so far clone works good, still waiting to get DRI to play with xrandr and xinerama, but to get recognized both monitors at the right resolution and bring them on is far more than fglrx could do, so big hopes here too
5.) CrossFireX: missing but in fglrx doesnt do a big job either so no big deal.but maybe AMD will release this doc eventually
or maybe we can think on a parallel method to get multiGPU togheter, dunno something like a joined framebuffer + some kind of GPUMP at drm lvl so to linux this is a 1600 unigpu with 2gb ram and not 2 4850 and this way we can avoid any kind of game side optimization, ahh just an idea
so basically im very pleased of the lvl of quality of the GIT radeon driver so far and if DRI works as expected at least to get my wine L2 installation + compiz working ill be as happy as i can ever be
update: about one gpu per monitor need more testing to see if both chips are active, i thought their was because both monitor render so fast in 2d, but with dri active later ill be sure if both go ative XD and about DRI asking in dri-devel yesteday finally got my hands on staging kernel, my pciid is still missing but thats easy to add so now i have to figth with mkpg which in ubuntu always provide a corrupted initrd so i cant boot staging or maybe is the XIP memory stuff in kernel config, mmmm tonigth ill get it done hopefuly.
update2: well with bridgman help i got drm/dri installed in a rv770 but is in not usable state the dri GL accel yet but the way feels good cuz everything else work pretty well like drm exa/xv accel.
1.) git a staging kernel to get latest drm (remember to check pciids in the sources files before compile)
2.) git a mesa r6xx-rewite branch (again check your pciids in radeon folder)
update3: this is the last post for me for next 2 month(big job came to me) so im going back to nvidia (a gtx260 from an office machine)in the meantime ill keep my 4850x2 so i can read the amd docs and try to help ppl in 3d support after this job.