Refund Boot support for Radeon graphics cards

[Ernesto J Hernandez]

I would like to know whether Refind would provide a boot screen with OS choices in macs with unflashed Radeon graphic cards. These cards boot into a dark screen. OS Sierra and High Siera provide drivers for these AMD cards, but the manufacturers do not provide macOS EFI support. I have a twelve core Mac Pro running OS Sierra with a flashed NVIDI card. NVIDIA has not released High Sierrs drivers. Suggestions would be much appreciated.

[Roderick W. Smith]

rEFInd is dependent upon EFI drivers for all hardware access (video, disks, etc.). Thus, anything without drivers -- either built into the card's firmware itself or loaded as a driver file -- will not work with rEFInd. If you can find a standalone driver file, you might be able to get it to work, as described in the rEFInd drivers documentation; however, I can't make any promises about that, since the rEFInd driver support has been tested mainly with filesystem drivers. There may be some difference between the way filesystem and video drivers must be loaded that rEFInd doesn't yet handle. Such a problem would be much easier to overcome than writing drivers from scratch, though.

Note that the OS or OS version you're booting has nothing to do with whether rEFInd will work with the hardware. That is, Nvidia driver support for Sierra vs. High Sierra is unrelated to what's needed to get rEFInd to work with your video card.

Some manufacturers provide firmware updates for their video cards to make them compatible with EFI firmware generically or with Apple's EFI implementation specifically. You may want to contact the manufacturer about this, or ask on a manufacturer or Mac forum. It's conceivable that "generic" EFI-compatible firmware would work with your card, but trying such firmware is risky -- you might easily "brick" the video card if the firmware you try to use doesn't work, or if you make a mistake while flashing it.

[Ernesto J Hernandez]

Thank you for the feedback. I know that EFI support has nothing to do with drivers. The reason I mentioned that subject was that, though I do get a boot screen from my flashed NVDIA card in High Sierra, the display is unusable. It flickers constantly and it causes the OS to malfunction. That is a function of the fact that NVIDA has not released drivers for High Sierra. Radeon cards, on the other hand, are natively supported in High Sierra. The problem is, however, that they boot into a black screen.

I would have to either abandon the idea of upgrading, or use two video cards as you mentioned. I do not have enough PCI space for two big graphic cards, though. Thanks again.