Why do Sapphire Pulse RX 580 UEFI cards need flashing?

[watkipet]

I was always under the impression that legacy VBIOS cards (Nvidia GTX 680, etc.) needed to have their ROMs modified to include UEFI support and then flashed in order for a Mac Pro to present a boot screen while booting with them.

However, I've heard that a Sapphire Pulse RX 580 UEFI card also needs to be flashed in order for a Mac Pro to show a boot screen with it as well. Why does the Sapphire card need flashing if it already supports UEFI? Is the Mac Pro only compatible with some special UEFI GOP driver?

 

[Pressure]

The Mac Pro uses the predecessor to UEFI, namely EFI.

 

[watkipet]

So does the Mac Pro use UGA instead of GOP? I'm getting my info from this post:

GA vs. GOP -- As you say, there are two EFI video systems, UGA and GOP. The latter was introduced with EFI 2.x (aka UEFI), IIRC, and AFAIK all UEFI-based systems use GOP. In principle, all EFI 1.x systems should use UGA; however, Apple (which still uses EFI 1.x, even in its most recent products) has ported UGA to its EFI, so some (but not all) Macs have EFI 1.x with GOP.​

 

[rawweb]

I was always under the impression that legacy VBIOS cards (Nvidia GTX 680, etc.) needed to have their ROMs modified to include UEFI support and then flashed in order for a Mac Pro to present a boot screen while booting with them.

However, I've heard that a Sapphire Pulse RX 580 UEFI card also needs to be flashed in order for a Mac Pro to show a boot screen with it as well. Why does the Sapphire card need flashing if it already supports UEFI? Is the Mac Pro only compatible with some special UEFI GOP driver?

FYI: There is no current flashable "Mac Edition" EFI for RX 580. This thread might be a good place to learn which cards are able to be flashed at this time. https://forums.macrumors.com/threads/all-the-flashable-gpus-for-mac-pro-update-jan-2018.2103531/

 

[h9826790]

So does the Mac Pro use UGA instead of GOP? I'm getting my info from this post:

GA vs. GOP -- As you say, there are two EFI video systems, UGA and GOP. The latter was introduced with EFI 2.x (aka UEFI), IIRC, and AFAIK all UEFI-based systems use GOP. In principle, all EFI 1.x systems should use UGA; however, Apple (which still uses EFI 1.x, even in its most recent products) has ported UGA to its EFI, so some (but not all) Macs have EFI 1.x with GOP.​

AFAIK, cMP is the only Mac that use UGA. GOP means nothing to the current cMP firmware.