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Issue getting OpenCore to work

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Hello there!

I hope this is correct, I have been reading the rules and threads and I think I am allowed to post here and ask for help. I am currently trying to get OpenCore to boot from a BIOS system and I struggle with getting it to work. I have tried different tools, manual setup, SD card in the SD card reader, two different USB drives, but really nothing works. Booting Grub or anything else from a USB works so I can not understand what my issue is.

 

Whatever I do when I try to boot from OpenCore all I get is a blinking underscore (which I assume is my BIOS because it does the same before booting Windows), but it never continues from the blinking underscore, it just stays there. Any advice or idea how to debug this issue would be greatly appreciated.

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Considering chainloading open core from grub2.

 

If you are a linux multi-booter and using grub2 as your main bootloader, and if you have an existing Catalina install with a working chainloaded OC or Clover, suggest you don't disturb/break your existing bootloader by making tweaks for Big Sur.  You can make an additional small 200MB FAT32 partition on your HDD and put your Big Sur bootloader there and chainload it from grub.cfg. Run lsblk -f or sudo blockid from linux terminal and note the UUID of the Big Sur FAT32 bootloader partition you made.  Temporarily edit your boot grub.cfg and add the following entry where xxxx-xxxx is your Big Sur FAT32 bootloader partition UUID:

 

for open core:

menuentry "Open_Core"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/OC/OpenCore.efi  # or whatever path you use
}

or for clover:

menuentry "Clover"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/CLOVER/CLOVERX64.efi  # or whatever path you use
}

 

This way you can easily edit/tweak your Big Sur bootloader settings without breaking your existing working ESP bootloader.  If you are not comfortable using an XML editor to edit config.plist, and you have Catalina installed, you can download ProperTree from github and use it from Catalina.  Later you can modify your linux /etc/grub.d/40_custom to include any custom bootloader menuentries you want to keep, and then run update-grub.

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Make sure that the folder structure is correct. It should be <Root of partition>/EFI/(BOOT or OC), not <Root of partition>/BOOT or <Root of partition>/OC. Pay extra attention if your partition is already named EFI.
Additionally, make sure your running the legacy boot utility under the OC Release/Utilities/BootLegacy (or LegacyBoot, I forget)

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5 hours ago, HenryV said:

Considering chainloading open core from grub2.

 

If you are a linux multi-booter and using grub2 as your main bootloader, and if you have an existing Catalina install with a working chainloaded OC or Clover, suggest you don't disturb/break your existing bootloader by making tweaks for Big Sur.  You can make an additional small 200MB FAT32 partition on your HDD and put your Big Sur bootloader there and chainload it from grub.cfg. Run lsblk -f or sudo blockid from linux terminal and note the UUID of the Big Sur FAT32 bootloader partition you made.  Temporarily edit your boot grub.cfg and add the following entry where xxxx-xxxx is your Big Sur FAT32 bootloader partition UUID:

 

for open core:

menuentry "Open_Core"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/OC/OpenCore.efi  # or whatever path you use
}

or for clover:

menuentry "Clover"{
    insmod part_gpt
    search --no-floppy --set=root --fs-uuid xxxx-xxxx
    chainloader /EFI/CLOVER/CLOVERX64.efi  # or whatever path you use
}

 

This way you can easily edit/tweak your Big Sur bootloader settings without breaking your existing working ESP bootloader.  If you are not comfortable using an XML editor to edit config.plist, and you have Catalina installed, you can download ProperTree from github and use it from Catalina.  Later you can modify your linux /etc/grub.d/40_custom to include any custom bootloader menuentries you want to keep, and then run update-grub.

Thank you for your reply, I must actually say that I don't have any OS on this machine right now, I have recently built it with discarded parts so there is no OS on it. I had started with OC and didn't get it to work, then tried Clover, same problem, then I even tried the DUET from Tianocore and still didn't work although with that one I at least got a welcome message.

 

The reason I tried Grub was because I was starting to suspect my machine just couldn't boot anything from USB, but since it booted up Grub perfectly fine that doesn't seem to be the problem. I tried to chainload OC from Grub but all I got was error messages of wrong signature. I think the problem was that my machine only supports BIOS so my installation of Grub didn't support the EFI file format.

 

Since nothing worked I decided to focus on trying the option I want to use, OS, to work.

Edited by nsn
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2 hours ago, 1Revenger1 said:

Make sure that the folder structure is correct. It should be <Root of partition>/EFI/(BOOT or OC), not <Root of partition>/BOOT or <Root of partition>/OC. Pay extra attention if your partition is already named EFI.
Additionally, make sure your running the legacy boot utility under the OC Release/Utilities/BootLegacy (or LegacyBoot, I forget)

Thank you for the reply, yes I have made sure the folder structure is correct and it's all on my USB drive so that is my root. Also I have always used the LegacyBoot.

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23 hours ago, HenryV said:

Wrong EFI signature is due to mismatched BIOS/EFI.

 

Grub installed in bios mode can use clover iso and grub4dos to start macOS.

 

Grub installed in EFI mode chainloads to clover or open core efi as per the menuentry examples.

Thank you for your reply, I actually used the Arch guide to install it in both modes on one USB drive, but I guess since I launch it from BIOS only the BIOS mode is available. Any way I can install Grub in BIOS mode and have it launch OC?

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