Can't use 4850 with Catalyst 8.8

[Tixer]

So I have an ATI Radeon 4850 on Ubuntu Hardy 64, and I want to be able to actually use my computer. I installed 8.7 initially with EnvyNG, but got a locked X session when I tried to reboot, with nothing on screen. I initially blamed this on Envy, but after trying to manually install 8.8 and getting this same problem, I've realized it isn't Envy.

I found a post on the Arch Linux forums explaining that there's some problem with having 4 gigs of RAM and a 512 meg graphics card. When I removed the second two gig stick, I was able to boot to my desktop. However, when I try to switch to compiz, I get a white screen and a cursor, and I can't do anything.

So tell me, is it possible to run compiz with any drivers + this card, or is it off limits for now. Also, what can I do to add in the second stick of RAM? I figured that by having a 64 bit OS, I wouldn't encounter RAM limitations, but is such truly the case?

[grantek]

Yep, I'm running a 4850 on a 64-bit OS, and it works fine for 64-bit native linux apps (has a hard time with 32-bit apps or wine/cedega).

Your problem is caused by something (I don't know what) not setting up the kernel's mtrr (http://en.wikipedia.org/wiki/Memory_Type_Range_Registers)s properly - the memory range that your graphics card sits at needs to be marked uncacheable.

Search the "Catalyst 8.[678] Released" threads for bridgman's posts on helping people with mtrr problems :)

[Tixer]

So I managed to fix that part, and 4 gigs of RAM works just fine. However, absolutely nothing I can do is getting the fglrx driver to work. I've reinstalled everything at least a dozen times, and tried just about everything, and I keep getting the mesa drivers to work.

Any ideas as to what I can do? I'm about ready to give up, since I've been trying for over 6 hours.

[Kano]

Install a 32 bit OS ;)

[adamk]

We would need to see your /var/log/Xorg.0.log file to determine why Xorg is falling back to mesa.

Adam

[Tixer]

I like my extra ram, kthx.

[Kano]

That's not the problem, you can use PAE enabled kernel to access all ram.

[Tixer]

http://pastebin.com/m7930e159

And I'd prefer not to have to reinstall. I have fake RAID here, and setting it up is painful.