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

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The first post of this thread is a WikiPost and can be edited by anyone with the appropiate permissions. Your edits will be public.
Bmju said:
They are both firmware, and both 'bios' (at least speaking loosely), and both EFI.
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Bmju said:
If you've already burnt your MacPro firmware, when upgrading from 4,1 to 5,1, or after boot rom cleaning service from @tsialex, then why not do the same again? You also get the advantage that very many different GPUs will all work for the native firmware UI (incl. native boot picker) from then on. But if you prefer to burn it to the GPU (and if it's not an AMD with too little space), then go ahead - it's your machine.
Click to expand...
When we have taken risks, does not mean that we should take them as much as possible.
That's why they are called risks. Every time is a risk.

But you do have a point here: if planning to use multiple GPUs, value of them might easilyexceed the value of cMP's motherboard.

It seems that even here in EU, professionals and companies are getting rid of their mp5,1s more and more. So it is now easier and cheaper to get a replacement.
 
tsialex said:
For all effects, the Mac Pro BootROM is read only. With the exception to the VSS stores inside the NVRAM volume, no one can modify it without entering Firmware Programming Mode.
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Do you remember what is WORM?

Have I something mixed up, when I think "firmware" update is writing to BootROM?

So, we need a new name for this media: WFTRM!
Write few times - read many.
 
At least for the iMacs the NVRAM and the BootROM (aka EFI firmware) reside in the flash memory of the SMC (System Management Controller).
Flash memory is technically a special type of EEPROM, as it has to be erased before writing to it (without erasing first only 1's can be turned into 0's).
 
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internetzel said:
At least for the iMacs the NVRAM together with the SMC firmware (responsible mainly for power management) and the BootROM (aka EFI firmware) reside in the flash memory of the SMC (System Management Controller).
Flash memory is technically a special type of EEPROM, as it has to be erased before writing to it (without erasing first only 1's can be turned into 0's).
Click to expand...

iMacs also have the NVRAM volume inside of the main SPI flash memory where the BootROM is stored and the main SPI flash memory is directly connected to the southbridge (earlier Intel Macs up to Westmere) or to the PCH (Sandy Bridge and later ones). No SMC involvement at all.

AFAIK, the only Intel Macs post 2007ish that have the NVRAM elsewhere of the main SPI flash memory are the T2 based ones and then the AS Macs. T2 Macs for legacy compatibility reasons also have a copy of the NVRAM outside of T2, but the main NVRAM is inside and T2 managed.

SMC and the SMC firmware are completely independent of the BootROM/NVRAM. SMC runs inside a secure microcontroller that is independent (and always powered on, so it is always monitoring) to the Intel processor. The SMC firmware is flashed internally to the Renesas H8S F2117TE20H microcontroller, the most commonly used as a SMC with Macs and have only 160KB of capacity:

Screen Shot 2024-02-18 at 21.32.48.png
 
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For example, this is the 2011 iMac12,1 SMC:

iMacSMC.jpg


The secure microcontroller that acts as SMC is the Renesas F2117TE20H H8S/2117V and is the exact same one as the MacPro5,1, but BGA instead of 144-pin TQFP. The early-2008 and late-2013 Mac Pros are also BGA like this iMac.

Back side of the same 2011 iMac12,1 logic board, this is the BootROM/NVRAM SPI flash memory (64Mb, double of the size of MacPro5,1, sames as MacPro6,1):
iMacSPI.jpg


I don't have a flashrom dump for this iMac12,1, so let's take a look at the signed capsule used for EFI firmware upgrades IM121_004D_00B_LOCKED.scap.

iMac_BootROM_NVRAMvolume.png


This is the signed capsule of the BootROM opened with UEFITool, see the NVRAM volume (GUID FFF12B8D-7696-4C8B-A985-2747075B4F50) inside the BootROM.


BootROM/NVRAM have to be connected to the southbridge/PCH and etc.
 
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What is the "official" name of this method?
"Enable GOP"?

Does this method widen in some way the compatibility of GPU's with different OS version in cMP?
Like listed in here:
blog.greggant.com

The Definitive Classic Mac Pro (2006-2012) Upgrade Guide

The largest/most-complete guide to all possible classic Mac Pro upgrades covering OS, Firmware, GPU, CPU, Storage, USB, THunderbolt and Network upgrades.
blog.greggant.com blog.greggant.com

Is it still that you need two GPU cards; one for running old OS and one for the new one?
 
toke lahti said:
Thank you.
How about putting these to the first post?
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They aren't questions that have come up much. I would probably leave these answers in the thread which people with the same questions can search for. Thank you.
 
Bmju said:
They aren't questions that have come up much. I would probably leave these answers in the thread which people with the same questions can search for. Thank you.
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I think the basic things would help people to get involved.

Now this thread and thereby the whole EnableGop has narrower following, because it's so nerdy.

You essentially published a book without a title or a cover.

If this is what you want, by all means, do not name your project.
'nuff said.
 
toke lahti said:
I think the basic things would help people to get involved.

Now this thread and thereby the whole EnableGop has narrower following, because it's so nerdy.

You essentially published a book without a title or a cover.

If this is what you want, by all means, do not name your project.
'nuff said.
Click to expand...
Well in case it helps people find it or understand it better, I added EnableGop to the thread title.
 
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Hello!

I understand that EnableGOP is for iMacs and Mac Pros. However, is it possible to enable the early macOS boot progress bar on a Windows PC as well?
Currently, I am trying to set up Big Sur from OpenCore in an environment where nVIDIA NVS 510 is the only video board, but I can only see a black screen.
 
seijits said:
Hello!

I understand that EnableGOP is for iMacs and Mac Pros. However, is it possible to enable the early macOS boot progress bar on a Windows PC as well?
Currently, I am trying to set up Big Sur from OpenCore in an environment where nVIDIA NVS 510 is the only video board, but I can only see a black screen.
Click to expand...
To be precise, the Boot picker is displayed, and after selecting Install, the macOS boot progress bar is displayed for a while, after which only a Black screen is displayed.
The debug log of OpenCore is interrupted in the middle of the boot, so the configuration of OpenCore is in the middle of the setting, but even if that problem did not exist, I understand that NVS 510 has a symptom where the macOS boot progress bar disappears in the middle.
 
seijits said:
Hello!

I understand that EnableGOP is for iMacs and Mac Pros. However, is it possible to enable the early macOS boot progress bar on a Windows PC as well?
Currently, I am trying to set up Big Sur from OpenCore in an environment where nVIDIA NVS 510 is the only video board, but I can only see a black screen.
Click to expand...
The way EnableGop works is very specific to the firmware of these ~2009-2012 Mac models, so there's no chance it can work as is on non-Apple firmware (nor even on Apple firmware of a different generation). It's also worth recalling that EnableGop delivers parts of OpenCore's graphics support, so it can't achieve anything different, once it's started, than OpenCore alone can achieve, once it's started.
 
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Bmju said:
The way EnableGop works is very specific to the firmware of these ~2009-2012 Mac models, so there's no chance it can work as is on non-Apple firmware (nor even on Apple firmware of a different generation). It's also worth recalling that EnableGop delivers parts of OpenCore's graphics support, so it can't achieve anything different, once it's started, than OpenCore alone can achieve, once it's started.
Click to expand...
Thank you for your reply. It’s a bit disappointing though.
Well, If I were to get a Mac Pro 5,1, would I insert EnableGop_x.x.efi or EnableGopDirect_x.x.efi into the vBIOS of NVS 510?
 
seijits said:
Thank you for your reply. It’s a bit disappointing though.
Click to expand...
Sorry!

seijits said:
Well, If I were to get a Mac Pro 5,1, would I insert EnableGop_x.x.efi or EnableGopDirect_x.x.efi into the vBIOS of NVS 510?
Click to expand...
Into main motherboard firmware is probably what I'd recommend, but into the VBIOS (aka GPU firmware, to be more precise) should also work fine.

I wouldn't necessarily buy a MacPro to match your graphics card ... ! ;) If you follow the dortania guides carefully, you can hopefully get macOS working on reasonable PC hardware.
 
Bmju said:
I wouldn't necessarily buy a MacPro to match your graphics card ... ! ;)
Click to expand...

Starting from the fact that the NVS 510 is a extremely poor choice for a Mac Pro.

It's a GK107-301-A2 based NVIDIA GPU, essentially a binned GT 640/740/K2000 with half the CUs, and the macOS driver for GK107 is known to buffer overflow and crash after some days of usage.
 
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tsialex said:
Starting from the fact that the NVS 510 is a extremely poor choice for a Mac Pro.

It's a GK107-301-A2 based NVIDIA GPU, essentially a binned GT 640/740/K2000 with half the CUs, and the macOS driver for GK107 is known to buffer overflow and crash after some days of usage.
Click to expand...
I think one of the advantages of NVS 510 is its single-slot low-profile form factor. But as you said, its performance is indeed poor.
 
Bmju said:
Sorry!


Into main motherboard firmware is probably what I'd recommend, but into the VBIOS (aka GPU firmware, to be more precise) should also work fine.

I wouldn't necessarily buy a MacPro to match your graphics card ... ! ;) If you follow the dortania guides carefully, you can hopefully get macOS working on reasonable PC hardware.
Click to expand...
Should I insert EnableGop_x.x.efi? Or EnableGopDirect_x.x.efi, if I were to prepare the poor NVS 510 for the Mac Pro and store it in a box.
 
I just looked at an auction site, and the Mac Pro 5.1 2010 was about $170. I’m not sure whether to buy it or not…
 
Bmju said:
I added NVS 510 to the list of supported cards based on this post to the thread: https://forums.macrumors.com/thread...s.2378942/page-29?post=32891085#post-32891085

So it looks like EnableGop is fine.
Click to expand...
I'm new at enableGOP, I was able to flash the bootRom and it works with all my cards except my RX580 Saphire w/ DVI 2 hdmi and 2 DP.. I get no video at all?
Do I need to use EnableGopDirect_1.4.ffs?

Note: I have 2 flashed RX580's and they work great without enableGOP but with enableGOP I get zero video.
I also have 2 RX580's that are not flashed and I want to use them with enableGOP.

Thanks
 
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