iM 4,1-14,4 EnableGop: Pre-OpenCore GOP support for EFI-era iMacs and Mac Pros

[MattMorris]

What was the issue w/ the bios?
Can you explain what was changed/patched?

It was very much beyond my knowledge, but....

1st attempt was "Changed GOP and changed internal place of training data (from 0x37000 to 0x38000)" which resulted in a pre-boot freeze of my cMP.

2nd attempt was "GOP only replacement". I'm not 100% clear if this included the above change, or reverted to my original vBIOS and then made the GOP replacement only.

All good now though!

 

[Borowski]

Hi,

could you also attach the repaired rom? Or @Ausdauersportler: Can you pls write something about the mods?
Thanks.

 

[MattMorris]

No problem, here it is:

 

[Borowski]

Thanks.
As i have no programming skills, i guess the only relevant change was to switch off a checking function (no operation) in GOP image.

OWC did some modification (don't know why) and forgot that will lead to "invalid" vbios and GOP will stop working.

 

[MattMorris]

Hello,

pls give this a try, ignore the information "unverified": https://www.techpowerup.com/vgabios/224008/224008

Just to tie things up, and something that may help other users attempting this - this vBIOS seems to be working well for me too. I'm getting the MacOS boot screen, the OC boot picker (without needing to inject as I did previously) and my 5.1 Mac Pro now boots into Mojave and Big Sur without issue.

Thanks for everyone's help!

 

[polanskiman]

Starting since last night I noticed some strange artefacts (short pink lines) appearing during the boot screen. They disappear once the boot process is finished. I did a deep NVRAM reset for good measure but that didn't fix the issue.
BootRom is injected with EnableGOP. I have not yet installed OpenCore.

What's up with that?

 

[Borowski]

Mine has the same problem sometimes, not permanent. Mostly at end of booting, before reaching login mask (the screen switches off for a moment). But it runs flawless under macOS and Windows, seems to be a driver issue?

 

[sfalatko]

This is a known artifact with EnableGop and nothing to worry about.

 

[polanskiman]

This is odd though, it only started happening for the past 2 days and only with one installation of macOS. The other 3 installs of macOS I have are not doing this.

 

[internetzel]

Acclerated graphics drivers take over while still on the loading screen (half way through, commonly) - the transition can only be expected to be seamless when using an Apple CoreEG2 VBIOS, but not when using a GOP driver.
After having loaded the GOP driver a complete reinitialisation of the attached displays seems to be performed while the Apple VBIOS seems to apply the exact same configuration to the displays as do the macOS drivers.

 

[Bmju]

This is a known artifact with EnableGop and nothing to worry about.

Syncretic mentions this as well, for his (completely separate from EnableGop) support for early graphics on non-natively supported cards: https://forums.macrumors.com/threads/mp4-1-5-1-looking-for-bootrom-beta-testers.2375345/ . Suspect it is macOS itself doing something which a few cards don't like.

 

[macCherroni]

works beautifully on my mac pro, the photo below is boot picker on my sapphire rx 580 8gb:

flashed to the built in mac pro firmware so it will carry over if i ever upgrade the gpu

Hi!! How did you do that? I'm having the boot rom reconstructed, I would love to include the boot picker in that

 

[John Fu]

just wonder if I do install Opencore first then can I use this to enable it?

Thank you

 

[Ausdauersportler]

just wonder if I do install Opencore first then can I use this to enable it?

Thank you

The great documentation is hidden here, which is the famous first wiki post of this thread. Having OpenCore in use helps to identify if your current graphics card + display setup will show an OC picker and later an EFI picker. But I am getting ahead of myself …

 

[ZNDK]

AMD RX Vega 56 not supported? I changed from RX580 to AMD RX Vega 56 and now the EnableGOP and BootPicker display is wrong.
I hover the mouse cursor near the volume icon and the volume icon appears. In the EnableGOP screen I can hover the mouse cursor over the volume icon and the volume icon appears. in the BootPicker it appears as if it is overlapping, like a drop shadow.

 

[Borowski]

Which version of gop enabler do you have in your firmware/gpu-bios?

 

[Bmju]

AMD RX Vega 56 not supported? I changed from RX580 to AMD RX Vega 56 and now the EnableGOP and BootPicker display is wrong.
I hover the mouse cursor near the volume icon and the volume icon appears. In the EnableGOP screen I can hover the mouse cursor over the volume icon and the volume icon appears. in the BootPicker it appears as if it is overlapping, like a drop shadow.

Oh look at that! That is the only other card other than the Radeon VII to display those artefacts. Although, there are success reports for Vega 56 if you search this thread. Can you try using EnableGopDirect instead? It would be very useful to know if that helps.

 

[ZNDK]

Which version of gop enabler do you have in your firmware/gpu-bios?

Version is 1.4. OpenCore is 0.9.6.

Can you try using EnableGopDirect instead? It would be very useful to know if that helps.

I tried to re-flush the ROM using EnableGopDirect.ffs.

./DXEinject originalROM.bin newROM.bin EnableGopDirect_1.4.ffs

However, the display does not change. The volume is drawn when the mouse is hovered over it. This is the same for both EnableGOP and OpenCore's BootPicker.

 

[Macschrauber]

Version is 1.4. OpenCore is 0.9.6.


I tried to re-flush the ROM using EnableGopDirect.ffs.

./DXEinject originalROM.bin newROM.bin EnableGopDirect_1.4.ffs

However, the display does not change. The volume is drawn when the mouse is hovered over it. This is the same for both EnableGOP and OpenCore's BootPicker.

have you double checked not to inject both EnableGop variants?

 

[Bmju]

have you double checked not to inject both EnableGop variants?

@Macschrauber has a point.

However, the display does not change. The volume is drawn when the mouse is hovered over it. This is the same for both EnableGOP and OpenCore's BootPicker.

Assuming that is not the issue, however, please try enabling DirectGopRendering quirk in your OC config.plist. Assuming your card is in fact behaving exactly like the Radeon VII, then you should find that this fixes the OpenCore menu (but not the pre-OC boot picker). Please do report back again! Thx.

 

[ZNDK]

Then my Mac (Ventura) went crazy and wouldn't start. It is as if it was a Big Sur situation. The startup progress bar stops at around 1/4 of the way up. That progress bar is also shrunk and displayed at the bottom. I have reverted to the normal EnableGOP.ffs and this symptom does not improve. I can't boot into recovery mode either, and a PRAM reset doesn't help either. I have also tried changing DirectGopRendering, GopBurst, etc. but no change.

 

[Bmju]

If you reverted to a previous firmware (i.e. the one with EnableGop) then it really should boot the same as it did before, with that firmware. At this point, are you really sure that you haven't added both EnableGopDirect and EnableGop? It does rather sound like it.

It sounds as if you could switch back to another graphics card to get a boot and reset your ROM.

 

[Macschrauber]

Then use the Dumper to check the firmware, it reports multiple EnableGop injections.

 

[ZNDK]

Finally my Mac was restored, OS (Ventura) reinstallation was not completed properly, and eventually the video card had to be temporarily replaced. I once back to RX580 and start Mac. Then I changed to RX Vega56 and now I can boot normally. But then the behavior is strange: when on Vega56, everything is heavy and sluggish; when I switch back to RX580, it's quick. Did something in this EnableGOP procedure negatively affect Vega56 itself or Mac?

At this point, are you really sure that you haven't added both EnableGopDirect and EnableGop? It does rather sound like it.

1. DXEinject originalROM.bin NewGOProm1.bin EnableGop_1.4.ffs
2. DXEinject NewGOProm1.bin NewGOPromComp.bin EnableGopDirect_1.4.ffs

Is it generated in two steps as described above?

 

[Macschrauber]

Finally my Mac was restored, OS (Ventura) reinstallation was not completed properly, and eventually the video card had to be temporarily replaced. I once back to RX580 and start Mac. Then I changed to RX Vega56 and now I can boot normally. But then the behavior is strange: when on Vega56, everything is heavy and sluggish; when I switch back to RX580, it's quick. Did something in this EnableGOP procedure negatively affect Vega56 itself or Mac?



1. DXEinject originalROM.bin NewGOProm1.bin EnableGop_1.4.ffs
2. DXEinject NewGOProm1.bin NewGOPromComp.bin EnableGopDirect_1.4.ffs

Is it generated in two steps as described above?

So you wrote both types.

Have you used my Dumper?

It should have warned you before flashing.

edit: Screenshots added