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I ended up using OCLP to get it working but is there anyway around having to hold the option key on boot up to select the efi folder. I have put the efi in the Mac Efi folder
You can do control+enter to bless the selection from the boot picker or you can bless the OC from the recovery partition as described in the first post.
 
See "Disabling OpenCore" and "Re-enabling OpenCore" in Part 3 of the guide. In recovery, before blessing OC, you can clear the NVRAM by entering nvram -c in terminal.
So I rebooted into Big Sur Recovery, cleared the NVRAM, blessed the Big Sur EFI, then rebooted. Big Sur booted as expected, even with the Mojave drive in bay 1. So I shut down the machine, installed the PCIe card with the SSD housing Windows 10 and powered on. It booted directly to Windows. I rebooted holding the escape key, but it didn't bring up the OC menu. It just booted straight to Windows.

I thought I followed your instructions to install Windows 10 perfectly, but it seems I didn't and it's in UEFI mode or something, because every time it boots, it ignores everything else in the machine.
 
I have a stock cMP3,1 and am interested in trying OCLP to see if it can boot Mojave or BigSur with a non-efi metal supporting gpu. Before I try anything, could you please answer the following:

a. Must the cMP3,1 be APFS enabled or is APFS booting taken care of by OCLP?

b. OCLP spoofs the cMP3,1 as a MP7,1. Is that more or less ok?

c. Must the config.plist be edited to include the PciRoot gpu path as obtained by gfxutil or will OCLP "find" the non-efi gpu? If yes, what should I add to the config.plist file and where?

d. If I pull all the drives out, replace the original gpu with the non-efi one, insert the (Mojave or BigSur) thumbdrive with OCLP-generated EFI folder copied to the thumbdrive EFI partition and "all goes well", what should I expect to see on the screen?
 
So I rebooted into Big Sur Recovery, cleared the NVRAM, blessed the Big Sur EFI, then rebooted. Big Sur booted as expected, even with the Mojave drive in bay 1. So I shut down the machine, installed the PCIe card with the SSD housing Windows 10 and powered on. It booted directly to Windows. I rebooted holding the escape key, but it didn't bring up the OC menu. It just booted straight to Windows.

I thought I followed your instructions to install Windows 10 perfectly, but it seems I didn't and it's in UEFI mode or something, because every time it boots, it ignores everything else in the machine.
Something's wrong here. We want a UEFI installation with OC. That's what the instructions are for. The instructions also make it difficult for Windows to boot on its own by omitting the Windows EFI BOOT folder.
 
Could it be the bit below?
What's odd is that if OC was blessed, then it should have remained blessed after adding the drive. Also odd is that the machine booted UEFI Windows on its own without the Windows BOOTX64.efi.
 
Could it be that the bless in Recovery was actually invalid?

If so, when the BS disk was attached, it could be that there was nothing specified and Mac OS just booted into an available instance. The Windows disk could then take precedence if it has the Windows fallback loader present when attached.
 
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Hi all

Could anyone advise me as to whether there's a way to stop a drive from mounting after booting Big Sur via OC?

Thanks!
 
What's odd is that if OC was blessed, then it should have remained blessed after adding the drive. Also odd is that the machine booted UEFI Windows on its own without the Windows BOOTX64.efi.
So when I mount the BS EFI volume, I see \EFI\EFI\BOOT\BOOTX64.efi. Is it supposed to be there?
 
So when I mount the BS EFI volume, I see \EFI\EFI\BOOT\BOOTX64.efi. Is it supposed to be there?
Yes, but the one belonging to OpenCore, not Windows. You can check that you have the right file by entering grep "Acidanthera" /Volumes/EFI/EFI/BOOT/BOOTx64.efi in terminal (make sure to mount the EFI volume first). You should see "Binary file /Volumes/EFI/EFI/BOOT/BOOTx64.efi matches".
 
Yes, but the one belonging to OpenCore, not Windows. You can check that you have the right file by entering grep "Acidanthera" /Volumes/EFI/EFI/BOOT/BOOTx64.efi in terminal (make sure to mount the EFI volume first). You should see "Binary file /Volumes/EFI/EFI/BOOT/BOOTx64.efi matches".
It matches.
 
Good. Are all your other EFI volumes empty?
The EFI volume on the Mojave disk contains EFI\EFI\APPLE\EXTENSIONS and \FIRMWARE. I don't know what the Windows disk has in its EFI, because as soon as I insert it, it boots to it, and there's no way to boot to macOS (Mojave or Big Sur).
 
Hi all

Could anyone advise me as to whether there's a way to stop a drive from mounting after booting Big Sur via OC?

Thanks!
Yes, you can by creating an fstab file in /etc. Follow these instructions for more information:


I've used the above to prevent my Mojave volumes from automatically mounting in Big Sur. I've also done the same in Mojave to stop BS volumes from mounting.
 
Yes, you can by creating an fstab file in /etc. Follow these instructions for more information:


I've used the above to prevent my Mojave volumes from automatically mounting in Big Sur. I've also done the same in Mojave to stop BS volumes from mounting.
Thanks! I knew about fstab, I also added the apfs staff at the end. I was wondering whether there is a way to do that in OC. Still, thanks once more!
 
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Thanks! I knew about fstab, I also added the apfs staff at the end. I was wondering whether there is a way to do that in OC. Still, thanks once more!
I looked before to see if OC could do this and didn't find a solution. Perhaps I didn't research well enough. I'd be interested to know either way as fstab isn't 100% perfect. For instance, I still get an error when booting into Mojave that one of Big Sur's volumes is incompatible with the OS even though none of them were mounted. I think it's the update volume Mojave is complaining about but not 100% sure.
 
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I looked before to see if OC could do this and didn't find a solution. Perhaps I didn't research well enough. I'd be interested to know either way as fstab isn't 100% perfect. For instance, I still get an error when booting into Mojave that one of Big Sur's volumes is incompatible with the OS even though none of them were mounted. I think it's the update volume Mojave is complaining about but not 100% sure.
Thanks for this. Every time I boot into Mojave it complains about incompatible disks so I'm going to try this method when I can.
 
Thanks for this. Every time I boot into Mojave it complains about incompatible disks so I'm going to try this method when I can.
Creating an fstab file will prevent auto mounting of volumes you specify, but since it happens only during OS startup, Mojave still polls the drives and returns that error. At least that's my theory.

Perhaps if OpenCore can do it before OS start, that problem would be solved. Given what I know of OC though, not sure it's feasible.
 
I looked before to see if OC could do this and didn't find a solution. Perhaps I didn't research well enough. I'd be interested to know either way as fstab isn't 100% perfect. For instance, I still get an error when booting into Mojave that one of Big Sur's volumes is incompatible with the OS even though none of them were mounted. I think it's the update volume Mojave is complaining about but not 100% sure.
The same here. I am not well versed in OC but searching about that issue led nowhere.

Thanks!
 
I looked before to see if OC could do this and didn't find a solution. Perhaps I didn't research well enough. I'd be interested to know either way as fstab isn't 100% perfect. For instance, I still get an error when booting into Mojave that one of Big Sur's volumes is incompatible with the OS even though none of them were mounted. I think it's the update volume Mojave is complaining about but not 100% sure.
You will not get around this error. Mojave and older versions on macOS have not been updated to understand the changes Apple introduced with Big Sur APFS.

Never touch an APFS partition for Big Sur with older versions of disk utility.

Keep everything separated - best case in separate disks, next best separate partitions.
 
You will not get around this error. Mojave and older versions on macOS have not been updated to understand the changes Apple introduced with Big Sur APFS.

Never touch an APFS partition for Big Sur with older versions of disk utility.

Keep everything separated - best case in separate disks, next best separate partitions.
Yep, that's why I use fstab to automatically unmount any OS volume not related to the one I'm currently booted into. It's not foolproof, but it at least adds one layer of security in the sense that I'd have to mount the drive before being able to do anything with it in disk utility.

Both Mojave and BS reside on separate physical SSDs.
 
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