Radeon Compatibility Guide - ATI/AMD Graphics Cards

[LostVector]

So in my continued quest to continue beating my head against a brick wall until this black screen problem is fixed, I have a new idea to explore.

The Apple EFI apparently disables the integrated GPU (or perhaps, just the "first") when third party OS's are loaded. This is because third party OS's have no idea how to handle the switching between integrated and discrete graphics and there's no way Apple will invest effort into maintaining other OS's.

There are special functions/vars that get set when macOS loads via the EFI on macOS hardware. There are options out there in other EFI loaders (such as recent versions of rEFInd ... see SetAppleOSInfo() and apple_set_os.efi that emulate the EFI code necessary to spoof the version correctly). Clover was forked from rEFit. rEFind (the current flavor) has the set os option, but apparently this never made it into Clover.

Perhaps all we need to do is port some of this code over to Clover? Or get apple_set_os.efi to chain through before macOS boots?

The thing is I don't understand exactly how a GPU could be getting disabled on third party hardware like a Hackintosh. In theory it should only happen on a genuine Mac, correct? But it seems awfully suspicious.

 

[VioletDragon]

Hi Fl0r!an. Ive took my 6870 apart put some new thermel pads and thermel paste on the GPU. done a fresh install of windows 7 on a old core 2 duo machine however i installed a program called GPU-Z its indicating that the GPU is at 35c and fan is at 40% but the fan seems to be on full throttle do you think i should find away to modify the BIOS and change the fan RPMs?

Update.

Ive managed to sort the FAN issue out. Ive changed the FAN speeds by modifying the BIOS. I just need a pair of active adaptors. Do you think two of these adaptor will work along with HDMI from the card that will allow me to use 3 monitors? https://www.amazon.co.uk/dp/B009YCE11E/?tag=tonymacx86-21

 

[Fl0r!an]

@LostVector: The AMD GPU doesn't get disabled by Clover/UEFI. It remains fully functional in OS X when removing the accelerator kext, so I think it's more likely that the GPU is left in a "bad"/unexpected state by the EFI, which causes the accerlerator kext to crash.

 

[LostVector]

@LostVector: The AMD GPU doesn't get disabled by Clover/UEFI. It remains fully functional in OS X when removing the accelerator kext, so I think it's more likely that the GPU is left in a "bad"/unexpected state by the EFI, which causes the accerlerator kext to crash.

Isn't it always the "first" card that seems to go dead? I have tried many scenarios and that seems to be the common theme. Yes, removing the accelerator kext does get it to go live, but that may simply be an accidental feature of an extremely outdated legacy driver, no?

Regardless, I'm digging through the code for Clover and there's nothing setting the os name and vendor properties in the UEFI, which definitely happens on a real Mac. It's also clear that the something disables the Integrated GPU (which could easily just be coded as "the first GPU") after EFI ExitBootServices is called if the name and vendor are not set ... I've seen this mentioned in multiple linux threads.

Of course I'm not going to be certain until something actually works, but there are too many similarities to ignore. We know real Mac's somehow don't have this problem, so we know they are doing something different at boot. The fact that this is all happening in the EFI loading process and that third party OS's like linux see similar disabling of GPU's on genuine Mac hardware without the variables being set ... it's just so similar in nature.

 

[Fl0r!an]

@LostVector: It's not necessarily the "first" card which will be dead, the bug only occurs when the AMD GPU has been init'ed by the UEFI driver, which isn't always the same.

Two examples from my system (other UEFI implementations can behave differently):

When booting with CSM disabled, the UEFI video driver will not be initialized when no display is connected to the AMD GPU during boot time, no matter if it's the primary or secondary video adapter. As a consequence the macOS drivers will work fine.

When booting with CSM enabled, firmware will always initialize the primary video adapter, regardless of any connected displays. To make a AMD GPU work in OS X, one has to configure it as secondary one.

The difference during boot phase is what we'd have to figure out to fix this issue.

 

[dbellog]

Hey guys, so I've been combing the boards for over a week. I picked up and xfx r9 280x double d (yeah I know now these are temperamental) ... I found a rom, updated the card and still getting the lockup 90% of the way through the black apple boot screen. Anyone have suggestions on a method or rom that I can try. Thanks

 

[timwharton]

I have a fully stable working rig with SMBIOS set as iMac 14.2 but only intel HD4600 as GPU, should i change it to a Mac Pro SMBIOS when i put the AMD r9 280x in? I have read these cards work OTB and use the built in macOS drivers but i am asking because Mac Pro have similar GPU's.

 

[Stork]

You can leave the SysDef at iMac14,2.

 

[LostVector]

@LostVector: It's not necessarily the "first" card which will be dead, the bug only occurs when the AMD GPU has been init'ed by the UEFI driver, which isn't always the same.

Two examples from my system (other UEFI implementations can behave differently):

When booting with CSM disabled, the UEFI video driver will not be initialized when no display is connected to the AMD GPU during boot time, no matter if it's the primary or secondary video adapter. As a consequence the macOS drivers will work fine.

When booting with CSM enabled, firmware will always initialize the primary video adapter, regardless of any connected displays. To make a AMD GPU work in OS X, one has to configure it as secondary one.

The difference during boot phase is what we'd have to figure out to fix this issue.

Interesting. Is it possible that Clover itself is causing the problem? Has anyone managed to boot macOS without Clover outputting to the graphics card?

A genuine Mac Pro 5,1 apparently does not use GOP to initialize the video card, only UGA. So if Clover always used GOP to draw its interface then perhaps that is giving the AMD driver fits.

 

[Fl0r!an]

It's true that the cMP uses the UGA protocol, but Apple has switched to GOP with all recent Macs. It's still possible that the GOP drivers on our graphics cards are causing the trouble, Apple might have included some special functions in their EFI drivers. I've already tried using the MacPro D700 EFI driver with my Radeon GPU, but my UEFI fails to utilize it (the driver loads fine, it just doesn't work).

I've also tried unloading the EFI driver from Clover's EFI shell before booting OS X, but that didn't work either.

It could also be a different part of the firmware, hard to tell.