AMD RX6600 & Rocket Lake on Catalina

[Middleman]

Hi guys,

I wanted to make a mention here, but about 3 months ago I had successfully booted a RX6600 card on Catalina 10.15.7. running a Rocket Lake i9-11900K setup.
This was the screen I captured:





As you know the card is only supported currently under macOS Monterey 12.0 only. So I am guessing you wondered how I managed to

get it to boot under Catalina? The answer lied with some CPUID spoofing and 3 system kexts.

Well I had spent some time looking at the AMD system kexts under /S/L/E in both Monterey and Catalina and I found that the clue was

actually to the three respective AMD kexts from Monterey - AMDRadeonX6000.kext, AMDRadeonX6000Framebuffer.kext, and

AMDRadeonX6000HWServices.kext. Under those kexts is the Info.plist file and the IOKitPersonalities class which contains the Vega

card models data, like the one shown below:



So to edit the files I turned SIP and GateKeeper off under Terminal. And then from the Monterey kexts I basically added new lines for AMDVega20Graphics under IOKitPersonalities to those in the existing Catalina version (AMDRadeonX5000.kext) that complimented how they should be in the Monterey version. Then after that, saved the 3 newly altered kexts onto the Desktop,

then copied them into Catalina. As I had an existing working OC 0.6.9 build which worked with Big Sur and Catalina I used that to boot into my system. That was it! The system booted straight in. Unfortunately I didn't do much further testing after that as I got busy, but I will be trying it again sometime soon.

And for getting the Rocket Lake to boot I simply used the CPUID1Data of EB060800 00000000 00000000 00000000 and CPUID1Mask of FFFFFFFF 00000000 00000000 00000000 as well as the following settings for the GPUs and platform:

 

[MaLd0n]

Monterey+ only

[Middleman]

11 minutes ago, MaLd0n said:

Monterey+ only

Hi MaLd0n,
 

Thanks and yes I am well aware the RX6600 is supported only under Monterey+ officially. This is actually a small guide I want to leave for anyone who wants to dabble

with the option of running it with Catalina or Big Sur. The screenshots above came out directly from the RX6600's HDMI output from Catalina.

[miliuco]

@Middleman

Great work.