ATI HD4850 & Mountain Lion

I know several people are having problems with this card and probably several others like it. It worked fine for me in Lion and I had to mess around with kext files less than I did to get it working in Snow Leopard. However, it's not working in Mountain Lion and the only way I can boot is with GraphicsEnabler=No (booting into safe mode doesn't even work, and that's what I had to do with Snow Leopard). Currently I am running off a user DSDT, whereas previously I believe I used EasyBeast, so perhaps that's an issue.

Booting into verbose mode, startup hangs here: siocprotodetach_in6 utun1 error 6 (see attached image).

I don't see what this error should have to do with the graphics card, so I'm wondering if there is some conflict rather than something directly related to graphics. I have tried using the Exotic Patch for 10.8 as well as the device injector, but nothing seems to work.

Any ideas?

I have tried tinkering around with various kexts: taking the ATI4800Controller.kext from the Lion S/L/E folder and replacing the same kext in the Mountain Lion install; deleting the ATI48xxInjector.kext from E/E; neither makes a difference. The verbose mode always stalls on the part described above, though what precedes it is not always the same.

When I boot into ML (thankfully I have a backup bootable drive of Lion from which I am writing this), I also seem to have some network problems (i.e., sometimes the wireless card just can't find any network, sometimes it can). I have the native airport card so I don't know why that would be an issue, but I wonder if there's some conflict there.

I'm tempted to get rid of the user DSDT and try EasyBeast but I don't have much reason to think that'll have an effect.

HELLO!!
I GOT IT FIXED
just visit QE_CI Exotic patch Mountain Lion GM - Downloads - OSx86.net
and download the QE/CI stuff...copy them into the system extensions folder
then run multibeast
then it's solved...mine work!!......hope it's gonna help you guys)

Would you be able to post a list of all the ATI related kexts in your S/L/E folder? I did try the patch without success, but I'm not sure it was applied properly. And when you say you ran Multibeast afterwards, what functions did you perform with Multibeast?

edit; nevermind about posting the files. I deleted all the ATI kexts I had so I could start fresh. Tried the Exotic Patcher, so far no luck but I'm tinkering around with device IDs and trying to determine if I need to insert a flag into my boot.plist.

I got rid of the siocprotodetach error by deleting a Cisco Anyconnect VPN program.

Then I got rid of the utun_ctl_connect error by disabling Back to My Mac in the iCloud settings.

Now I am hanging on these two lines:

Sandbox: sandboxd(106) deny mach-lookup com.apple.coresymbolicationd
considerRebuildOfPrelinkedKernel com.apple.driver.AppleHWSensor triggered rebuild

Just add your ID(0x94421002) in the ATI4800controller.I have the same card and it worked with this method plus dsdt since Lion.

Thanks, but I have done that and still have the problem. What other ATI related kexts have you installed?

For my pc,I edited ATI4800conroller.kext,Applehda.kext,AppleRTC.kext these 3 kexts. For ethernet card,I install AttansicL1eEthernet.kext
my pc spec:
mb : Asus P5Q
Ram : 4 G
Graphic card: Gigabyte ATI4850 512g
on board sound car :ALC1200

i put the two files that i downloaded into system/resources/extensions
and ran multibeast with
easybeast
system utilities
that's all how i fixed my graphics problem....

Just an update, I did a clean install with the Exotic Patch for 10.8 and everything works brilliantly now. There must have been some conflict with the kext files from so many upgrades, etc. Pretty happy with how this is working so far, though.