Resolved Boot menus for graphics output protocol.(AMD only)see page 13

[AdamR01]

Really no one to test it, @h9826790 tried it, and it doesn't seem to work, but I'm not sure if that has to do with a non-standard display "he's" using.

I tested it best I could, and it seemed to work just fine on my UEFI system. When I loaded rEFInd the screen resolution changed to the max supported by the monitor. However that system already loaded the GOP rom. Now I've had a chance to look at my settings in UEFI, I see that I can chose legacy boot for PCI cards, that should load the bios video driver, then I can load rEFInd and see if the GOP driver gets loaded.

Tho, I'm not real motived to do it if there isn't anyone with a Mac Pro that cares about boot screens for PC video cards, one day, when they are a little cheaper, I'll pickup a cheese grader and get all this stuff working, until then I'd need at least a few bata testers to figure this out.

I just saw your thread where you posted the original code, not this one. I couldn't get the code to compile on Linux (it looks like it was hacked to compile on OS X). The mainline rEFInd is up to 0.11.2 now (with a few High Sierra fixes) so I ended up getting the source and patching it with the code in screen.c. When I attempt to boot with my RX 560 installed I get a black screen only and nothing seems to be responding. rEFInd does still work if I reinstall my 5770.

 

[MriX]

Really no one to test it, @h9826790 tried it, and it doesn't seem to work, but I'm not sure if that has to do with a non-standard display "he's" using.

I tested it best I could, and it seemed to work just fine on my UEFI system. When I loaded rEFInd the screen resolution changed to the max supported by the monitor. However that system already loaded the GOP rom. Now I've had a chance to look at my settings in UEFI, I see that I can chose legacy boot for PCI cards, that should load the bios video driver, then I can load rEFInd and see if the GOP driver gets loaded.

Tho, I'm not real motived to do it if there isn't anyone with a Mac Pro that cares about boot screens for PC video cards, one day, when they are a little cheaper, I'll pickup a cheese grader and get all this stuff working, until then I'd need at least a few bata testers to figure this out.

Maybe I have some time to test it this weekend.
It would be nice when you also share how you compiled it.

 

[Jake Bloom]

I have a 5,1 tower and will be buying a RX 580 soon. I am currently using rEFInd as my system is multi-boot with El Captain, Linux and Windows 10. I will let you know once I get the card and get it all set up. I will be upgrading the Mac OS to support the new card.

 

[DearthnVader]

Maybe I have some time to test it this weekend.
It would be nice when you also share how you compiled it.

I used the instructions here:

https://github.com/jief666/refind-edk2

I had to use an older version of XCode 8.2 with the command line tools for Xcode 8.2. I did it on High Sierra by renaming Xcode to Xcode 9 and installing Xcode 8.2 and it's command line tools. You'll get an error at one point about needing mtoc, and you'll need to fallow the instructions here:

https://github.com/tianocore/tianocore.github.io/wiki/Xcode

Once your done, you can just rename Xcode to Xcode 8, and rename Xcode 9 back to Xcode. Then reinstall the command line tools for Xcode 9.

Tho I have access to all the old versions of Xcode and it's command line tools, from:

https://developer.apple.com/download/more/

 

[DearthnVader]

I just saw your thread where you posted the original code, not this one. I couldn't get the code to compile on Linux (it looks like it was hacked to compile on OS X). The mainline rEFInd is up to 0.11.2 now (with a few High Sierra fixes) so I ended up getting the source and patching it with the code in screen.c. When I attempt to boot with my RX 560 installed I get a black screen only and nothing seems to be responding. rEFInd does still work if I reinstall my 5770.

Ok, I tested on my system too, I don't have a MacPro, but my UEFI bios will let me select legacy for PCI-E card booting.

Clover's shell reports Bios Init Video driver, so I booted this version rEFInd then I booted Clover's shell, and there is no GOP video driver loaded.

It's just not working, and it doesn't seem to even attempted to load the GOP drive. It only boots to text mode on my system, tho it does report the screen is UEFI Video.

When I enable UEFI first for my PCI-E devices in my "bios", Clover's shell reports AMD GOP driver for my Graphics card.

Jief said he really didn't have time to work on this right now, when I asked him about the code he put in for debugging, and looking around for info on debugging rEFInd, there really isn't any code for it. Meaning it has no debugging log ability.

So, I'm not wanting to reinvent the wheel, Jief took this code from Clover, and one users on this forum reported that they were able to get boot video on a Mac Pro with Clover in UEFI mode.

With Clover there are two ways to get Video for Clover's boot menu, one is using Clover Legacy( Bios Video ). Because the Mac Pro has CSM( or Bios Compatibility ), booting Clover Legacy will get you video the same way booting Windows installed with bootcamp will, giving you Clover's Boot Menu.

The other way is to boot Clover in EFI mode, and let Clover's code, the code Jief used for rEFInd, lode the GOP driver, and again you'll get Clover's boot menu.

There is a little drawback to this, as Clover is meant to patch things for a Hackintoch, but they can be over come.

Clover has debug logging ability, so if it doesn't get video in EFI mode, we can try and debug it, rEFInd just doesn't have it, and I don't feel like adding it in.

Let me know if you want to try and use Clover to get boot menu's in UEFI or Legacy mode, and I'll post some instruction on it.

 

[h9826790]

Ok, I tested on my system too, I don't have a MacPro, but my UEFI bios will let me select legacy for PCI-E card booting.

Clover's shell reports Bios Init Video driver, so I booted this version rEFInd then I booted Clover's shell, and there is no GOP video driver loaded.

It's just not working, and it doesn't seem to even attempted to load the GOP drive. It only boots to text mode on my system, tho it does report the screen is UEFI Video.

When I enable UEFI first for my PCI-E devices in my "bios", Clover's shell reports AMD GOP driver for my Graphics card.

Jief said he really didn't have time to work on this right now, when I asked him about the code he put in for debugging, and looking around for info on debugging rEFInd, there really isn't any code for it. Meaning it has no debugging log ability.

So, I'm not wanting to reinvent the wheel, Jief took this code from Clover, and one users on this forum reported that they were able to get boot video on a Mac Pro with Clover in UEFI mode.

With Clover there are two ways to get Video for Clover's boot menu, one is using Clover Legacy( Bios Video ). Because the Mac Pro has CSM( or Bios Compatibility ), booting Clover Legacy will get you video the same way booting Windows installed with bootcamp will, giving you Clover's Boot Menu.

The other way is to boot Clover in EFI mode, and let Clover's code, the code Jief used for rEFInd, lode the GOP driver, and again you'll get Clover's boot menu.

There is a little drawback to this, as Clover is meant to patch things for a Hackintoch, but they can be over come.

Clover has debug logging ability, so if it doesn't get video in EFI mode, we can try and debug it, rEFInd just doesn't have it, and I don't feel like adding it in.

Let me know if you want to try and use Clover to get boot menu's in UEFI or Legacy mode, and I'll post some instruction on it.

Thanks for the detail explanation. I would like to try to use Clover to show boot screen.

I tried few different way, but can't quite get it (Clover work on my 7950 Mac Editing card, so, the installation is fine). If you don't mind to post some instructions here, I will try that and report back.

Understand that there are 2 possible ways to get it work. If possible, I would like to try the EFI mode. I think that will provide better display quality. Million thanks in advance.

 

[DearthnVader]

Thanks for the detail explanation. I would like to try to use Clover to show boot screen.

I tried few different way, but can't quite get it (Clover work on my 7950 Mac Editing card, so, the installation is fine). If you don't mind to post some instructions here, I will try that and report back.

Understand that there are 2 possible ways to get it work. If possible, I would like to try the EFI mode. I think that will provide better display quality. Million thanks in advance.

I'll have to go back and find the old thread about it, and see if we can figure out the magic needed to get Clover to init GOP video.

EDIT:Ok, I took a look back, it seems you took part in the old threads about it, but could never get it to work. Not sure what magic the other two that reported it to work used, but I suppose inststall Clover for UEFI and to the ESP of a disk, and maybe chose inject ATI/Nvidia, then bless the clover EFI file and reboot to see if you get anything, we'll go from there.

sudo bless --mount /Volumes/ESP --setBoot --file /Volumes/ESP/efi/boot/bootx64.efi --verbose

That assumes you mounted the ESP partition of your disk as "ESP", if you use Clover Configurator it will mount it as "EFI" so you'll need to adjust the command:

sudo bless --mount /Volumes/EFI --setBoot --file /Volumes/EFI/efi/boot/bootx64.efi --verbose

 

[h9826790]

I'll have to go back and find the old thread about it, and see if we can figure out the magic needed to get Clover to init GOP video.

EDIT:Ok, I took a look back, it seems you took part in the old threads about it, but could never get it to work. Not sure what magic the other two that reported it to work used, but I suppose inststall Clover for UEFI and to the ESP of a disk, and maybe chose inject ATI/Nvidia, then bless the clover EFI file and reboot to see if you get anything, we'll go from there.

sudo bless --mount /Volumes/ESP --setBoot --file /Volumes/ESP/efi/boot/bootx64.efi --verbose

That assumes you mounted the ESP partition of your disk as "ESP", if you use Clover Configurator it will mount it as "EFI" so you'll need to adjust the command:

sudo bless --mount /Volumes/EFI --setBoot --file /Volumes/EFI/efi/boot/bootx64.efi --verbose

Thanks for the support. Let's do it step by step together. Make sure we are on the same pace. And the others are more easier to follow. So, start with Clover installation.

Run Clover 2.4k r4297 installer.

Select destination, in my case, this 8TB backup HDD has daily backup of my primary boot drive. A full up to date MacOS is there. And tested bootable.

Choose custom install, tick "Install Clover in the ESP", and leave all other option as default setting.

Is that the correct way to do it? Or we should tick some Drivers option? From what I can see, there is no option about installing the video driver.

 

[DearthnVader]

Thanks for the support. Let's do it step by step together. Make sure we are on the same pace. And the others are more easier to follow. So, start with Clover installation.

Run Clover 2.4k r4297 installer.
View attachment 739532
Select destination, in my case, this 8TB backup HDD has daily backup of my primary boot drive. A full up to date MacOS is there. And tested bootable.
View attachment 739533
Choose custom install, tick "Install Clover in the ESP", and leave all other option as default setting.
View attachment 739534 View attachment 739535
Is that the correct way to do it? Or we should tick some Drivers option? From what I can see, there is no option about installing the video driver.
View attachment 739538 View attachment 739539

Look like you need to check Install for UEFI booting.

 

[h9826790]

Look like you need to check Install for UEFI booting.

OK, so if choose Install for UEFI booting ONLY. Then some options will be grey out, and the CloverEFI will NOT be installed. We try this config?

 

[DearthnVader]

OK, so if choose Install for UEFI booting ONLY. Then some options will be grey out, and the CloverEFI will NOT be installed. We try this config?
View attachment 739546

I'm not sure what the difference is, other than the driversx64 vs. driversx64UEFI. Really none of the drivers should be needed, and may cause trouble on a real Mac, but some maybe needed, and it would be nice to know what drivers from Clover work with a real Mac, but that's something for a later date.

Let's just try it with install to ESP and UEFI booting only, and see what that gets us.

The options that are greyed out are for legacy booting, the first one Bootlaoder is the first stage boot loader that gets written to the MBR of a disk for legacy booting. Even GUID disks have this, and I have used it to boot clover on a pure GUID disk in a bios based system. All it does is load the second stage bootlaoder, the "boot" file.

That leads us to the second option that is greyed out, Clover EFI, that is the file "boot", and what it is, is Clover's implementation of EDK. I'm thinking it's basically Duet, an EFI system that predates EDK II, or UEFI.

Anyway, it's only needed for legacy booting.

The last things that are greyed out "Drivers64" are the drivers used when booting legacy, and would just be ignored if you boot Clover in UEFI mode, as it uses the drivers in driversx64UEFI, vice versa.

 

[h9826790]

I'm not sure what the difference is, other than the driversx64 vs. driversx64UEFI. Really none of the drivers should be needed, and may cause trouble on a real Mac, but some maybe needed, and it would be nice to know what drivers from Clover work with a real Mac, but that's something for a later date.

Let's just try it with install to ESP and UEFI booting only, and see what that gets us.

The options that are greyed out are for legacy booting, the first one Bootlaoder is the first stage boot loader that gets written to the MBR of a disk for legacy booting. Even GUID disks have this, and I have used it to boot clover on a pure GUID disk in a bios based system. All it does is load the second stage bootlaoder, the "boot" file.

That leads us to the second option that is greyed out, Clover EFI, that is the file "boot", and what it is, is Clover's implementation of EDK. I'm thinking it's basically Duet, an EFI system that predates EDK II, or UEFI.

Anyway, it's only needed for legacy booting.

The last things that are greyed out "Drivers64" are the drivers used when booting legacy, and would just be ignored if you boot Clover in UEFI mode, as it uses the drivers in driversx64UEFI, vice versa.

OK, Clover installed as per discuss (UEFI boot only), and Clover configurator shows the following.

Graphics, Inject NVidia NOT selected yet.

Boot page, nvda-drv=1 NOT selected yet

Boot graphic page, nothing to config, posted here for your reference if relevant

Gui page, Screen Resolution set to 1920x1080 and language en (default 1280x1024, no language selected).

Acpi page, Nvidia not selected.

Should I alter any of these setting? (My GPU is a non flashed 1080Ti. Screen native resolution is 3840x1080, but can config to act as a standard 1080P60 monitor)

P.S. I removed ALL rEFInd related material in the EFI partition.

 

[h9826790]

The EFI partition is properly mounted, but the bless command seems to return some error.

Update 1:
It's the mount method's issue.

When installed Clover, the installer mount the EFI partition. If I leave it mounted, the bless command won't work.

But if I eject it, then mount again by using Clover configurator, then the bless command does work properly.

[doublepost=1512152970][/doublepost]1st attempt is done. Nothing display as expected because didn’t inject anything.

But good news is Clover is working. Caps lock key react during black screen. And blindly press Enter can continue to boot to desktop.
[doublepost=1512154662][/doublepost]Anyway, 2nd attempt also finished, the only change is "Inject Nvidia" Selected. This time still no boot screen, and the 5 second time out seems kick in, and continue to boot to OS without any keyboard input.

[doublepost=1512155290][/doublepost]3rd attempt. NvidiaGeneric selected, same result, auto boot to desktop after 5 seconds timeout.

I am now changed the time out to 20 seconds, make sure it's enough time for my screen to wake up. Also, make me easier to "feel" if the time out is really there.

 

[h9826790]

4th attempt. Load VBios selected. Same result, auto boot to OS after time out.

I can clearly feel the 20s time out. Therefore, I reduce it to 10s now.

[doublepost=1512156636][/doublepost]5th attempt. nvda_drv=1 selected, nil help, no boot screen, and auto boot to desktop after 10s time out.

 

[DearthnVader]

Must be some magic to get Clover to load the GOP driver, the load VBios command loads a Vbios from file, it must be in the Clover/misc folder and named VendorID_DeviceID, so 10de_xxxx, replace xxxx with your 1080's device ID.

It maybe necessary to use a pure UEFI Rom, without the legacy Bios, but no one that got it to work ever said that, tho they didn't say anything about how they got it to work.

 

[h9826790]

6th attempt. The very last parameter I can think of is the "Nvidia" check box in the Acpi page. Tick it, and still no boot screen. 10s time out, auto boot to OS.

[doublepost=1512158174][/doublepost]

Must be some magic to get Clover to load the GOP driver, the load VBios command loads a Vbios from file, it must be in the Clover/misc folder and named VendorID_DeviceID, so 10de_xxxx, replace xxxx with your 1080's device ID.

It maybe necessary to use a pure UEFI Rom, without the legacy Bios, but no one that got it to work ever said that, tho they didn't say anything about how they got it to work.

Not sure if this driver is required. I just install it anyway.

Thanks for this extra info. I just copy my 1080Ti's ROM image file to the misc folder, and rename it to 10de_1b06.rom

[doublepost=1512158474][/doublepost]With the above changes, 7th attempt still not there yet. Same result, black screen for 10s, then auto boot to OS.
[doublepost=1512159247][/doublepost]Just found one more Nvidia related variable. "NvidiaWeb" in System Parameters page, 8th attempt done, confirmed nil help.

 

[h9826790]

9th attempt after some reading, move the 1080Ti's ROM image file to EFI/EFI/Clover/ROM/, nil help.

Clover is definitely loaded. My cMP's Serial Number changed, PCIe info messed up. But a bonus is that the Audio via Display Port suddenly work if I load MacOs via Clover.

[doublepost=1512167295][/doublepost]Just found something interesting.

After installing Clover, my cMP reported that SIP is Enabled. (I only discovered this 20min ago)

But I never perform any PRAM reset, and I am sure it didn't reset itself (otherwise I will only have black screen).

This "SIP Enabled" not just happen in the Clover boot, but also normal boot.

I boot into single user recovery partition to disable SIP, but after reboot, it still shows SIP Enabled.

And now is the funny part. With the system reported that SIP Enable. BootChamp still working. unsigned kext still loaded. And I can still alter the system files. 100% sure SIP is not working.

I personally don't mind this, because I want to keep it disabled anyway. But for those who care about SIP. May be you should test your SIP protection. Even though I only notice this 20min ago. It may be Clover irrelevant, and actually a serious bug in the current MacOS build.

 

[Jake Bloom]

I have not read much on Clover because I never intended to build a hackintosh. Very interesting idea trying to use it to enable boot screens.

 

[DearthnVader]

9th attempt after some reading, move the 1080Ti's ROM image file to EFI/EFI/Clover/ROM/, nil help.

Clover is definitely loaded. My cMP's Serial Number changed, PCIe info messed up. But a bonus is that the Audio via Display Port suddenly work if I load MacOs via Clover.
View attachment 739639 View attachment 739640 View attachment 739641
[doublepost=1512167295][/doublepost]Just found something interesting.

After installing Clover, my cMP reported that SIP is Enabled. (I only discovered this 20min ago)
View attachment 739645
But I never perform any PRAM reset, and I am sure it didn't reset itself (otherwise I will only have black screen).

This "SIP Enabled" not just happen in the Clover boot, but also normal boot.

I boot into single user recovery partition to disable SIP, but after reboot, it still shows SIP Enabled.

And now is the funny part. With the system reported that SIP Enable. BootChamp still working. unsigned kext still loaded. And I can still alter the system files. 100% sure SIP is not working.
View attachment 739647
I personally don't mind this, because I want to keep it disabled anyway. But for those who care about SIP. May be you should test your SIP protection. Even though I only notice this 20min ago. It may be Clover irrelevant, and actually a serious bug in the current MacOS build.

Let's have a look at your Clover boot log, here's the section we want to look at, then we need to put Clover in debug mode:

0:679  0:000  === [ InitScreen ] ========================================
0:679  0:000  SetScreenResolution: 1024x768 - already set
0:679  0:000  Console modes reported: 4, available modes:
0:679  0:000   - [01]: 80x25 (current mode)
0:679  0:000   - [03]: 100x31
0:679  0:000   - [04]: 128x40
0:679  0:000  SetScreenResolution: 1024x768 - already set
0:679  0:000  reinit: self device path=PciRoot(0x0)\Pci(0x1F,0x2)\Sata(0x1,0xFFFF,0x0)\HD(1,GPT,19CF81A5-0F28-4186-8330-380219FAD3C7,0x28,0x64000)

In Clover Configurator under Boot at the right click the debug check box.

Then reboot and you should find the log in /EFI/Clover/misc

 

[h9826790]

Let's have a look at your Clover boot log, here's the section we want to look at, then we need to put Clover in debug mode:

0:679  0:000  === [ InitScreen ] ========================================
0:679  0:000  SetScreenResolution: 1024x768 - already set
0:679  0:000  Console modes reported: 4, available modes:
0:679  0:000   - [01]: 80x25 (current mode)
0:679  0:000   - [03]: 100x31
0:679  0:000   - [04]: 128x40
0:679  0:000  SetScreenResolution: 1024x768 - already set
0:679  0:000  reinit: self device path=PciRoot(0x0)\Pci(0x1F,0x2)\Sata(0x1,0xFFFF,0x0)\HD(1,GPT,19CF81A5-0F28-4186-8330-380219FAD3C7,0x28,0x64000)

In Clover Configurator under Boot at the right click the debug check box.

Then reboot and you should find the log in /EFI/Clover/misc

Definitely something wrong here.

0:227 0:001 === [ InitScreen ] ========================================
0:227 0:000 SetScreenResolution: 1920x1080 - not found!
0:227 0:000 SetMaxResolution: found best mode 0: 0x0
0:227 0:000 - already set
0:227 0:000 Console modes reported: 1, available modes:
0:227 0:000 - [01]: 80x25 (current mode)
0:227 0:000 SetScreenResolution: 1920x1080 - not found!
0:227 0:000 reinit: self device path=PciRoot(0x0)\Pci(0x1F,0x2)\Sata(0x2,0x0,0x0)\HD(1,GPT,512E9338-97FA-49A2-9EFC-07DE40B22916,0x28,0x64000)
[doublepost=1512235936][/doublepost]Just tired the default Clover setting. Same result.

0:227 0:001 === [ InitScreen ] ========================================
0:227 0:000 SetScreenResolution: 1280x1024 - not found!
0:227 0:000 SetMaxResolution: found best mode 0: 0x0
0:227 0:000 - already set
0:227 0:000 Console modes reported: 1, available modes:
0:227 0:000 - [01]: 80x25 (current mode)
0:227 0:000 SetScreenResolution: 1280x1024 - not found!
0:227 0:000 reinit: self device path=PciRoot(0x0)\Pci(0x1F,0x2)\Sata(0x2,0x0,0x0)\HD(1,GPT,512E9338-97FA-49A2-9EFC-07DE40B22916,0x28,0x64000)
[doublepost=1512236756][/doublepost]Just make few more little test. Force the screen to run at 1080P60 doesn't help. Use HDMI port doesn't help. Use different DP port doesn't help. And DP1.1, DP1.2, DP1.2+ makes no difference. However, that’s base on my current Clover setting, I don’t even know if it’s correct. There is a possibility that only a certain Clover config + DP1.1 (etc) can work.

And the log file is attached.

 

[Fl0r!an]

Hehe, I must have been really lucky when (successfully) tried using Clover for getting boot screens last year. Most of those settings are not relevant until macOS has booted, so I guess it might only work on a special Clover release (or with specific GPUs?).

I currently can't replicate what I've done as I don't have access to a Mac Pro right now, but I can tell you that I was using my Sapphire R9 280 with stock UEFI Hybrid VBIOS. I just had a look in my downloads folder and I think I've been using Clover R3424. Maybe I had CsmVideoDxe installed, not sure.

Good luck!

 

[DearthnVader]

Hehe, I must have been really lucky when (successfully) tried using Clover for getting boot screens last year. Most of those settings are not relevant until macOS has booted, so I guess it might only work on a special Clover release (or with specific GPUs?).

I currently can't replicate what I've done as I don't have access to a Mac Pro right now, but I can tell you that I was using my Sapphire R9 280 with stock UEFI Hybrid VBIOS. I just had a look in my downloads folder and I think I've been using Clover R3424. Maybe I had CsmVideoDxe installed, not sure.

Good luck!

I was looking over some of the Clover source code, and some of the GOP code was commented out, so older versions of Clover may have something changed that is preventing us from success.

I've got to setup a new Clover build env, then I can make some builds that may help.

 

[h9826790]

Hehe, I must have been really lucky when (successfully) tried using Clover for getting boot screens last year. Most of those settings are not relevant until macOS has booted, so I guess it might only work on a special Clover release (or with specific GPUs?).

I currently can't replicate what I've done as I don't have access to a Mac Pro right now, but I can tell you that I was using my Sapphire R9 280 with stock UEFI Hybrid VBIOS. I just had a look in my downloads folder and I think I've been using Clover R3424. Maybe I had CsmVideoDxe installed, not sure.

Good luck!

Thanks for giving us some extra info. May be I will try few more different versions of Clover.

I tried CsmVideoDxe, the log shows successfully loaded, but nothing change, still black screen.

Anyway, it’s interesting to use Clover to show boot screen on a card that can easily flash with Mac EFI. I am thinking if that’s related.

 

[DearthnVader]

Thanks for giving us some extra info. May be I will try few more different versions of Clover.

I tried CsmVideoDxe, the log shows successfully loaded, but nothing change, still black screen.

Anyway, it’s interesting to use Clover to show boot screen on a card that can easily flash with Mac EFI. I am thinking if that’s related.

Beware, older versions of Clover won't be able to boot High Sierra, so you may end up reinstalling your Apple EFI GPU if you get stuck with no display. However, it would be interesting to know if Clover lost this function at some point.

I'm assuming it did, and it has something to do with the GOP code that is commented out in newer Clover source.

Clover was never trying to add GOP boot screens to a real Mac, I think the GOP code was for UEFI booting, and it just had the side effect of getting boot screens on a real Mac. Likely they changed the way the code works for better compatibility with PC UEFI, and as a result it broke GOP rom loading on a real Mac.

 

[h9826790]

Beware, older versions of Clover won't be able to boot High Sierra, so you may end up reinstalling your Apple EFI GPU if you get stuck with no display. However, it would be interesting to know if Clover lost this function at some point.

I'm assuming it did, and it has something to do with the GOP code that is commented out in newer Clover source.

Clover was never trying to add GOP boot screens to a real Mac, I think the GOP code was for UEFI booting, and it just had the side effect of getting boot screens on a real Mac. Likely they changed the way the code works for better compatibility with PC UEFI, and as a result it broke GOP rom loading on a real Mac.

Thanks for the reminder. I should be very safe on this. Because if anything goes wrong, I can pull out the test drive, then the cMP should automatically revert to the primary SSD and continue to boot.

And as you said, in worst case, just install the Mac EFI GPU. Nothing need to fear. Compare to the potential benefit of this project, I am more than happy to take this damageless risk.

Anyway, I tried the most up to date Clover, it doesn't work.

May be I can try R3424 tonight.

Do you know the "not supporting HS" means "unable to boot HS in all case"? Or unable to boot APFS HS? Or may be it can boot HS on a real Mac?