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Guide: Multibooting UEFI on Separate Drives

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@Going Bald, @cmorellato, thanks to you both for your replies and your patience. I did manage to get the Multi-Boot working finally and I am very grateful for your help.

I think that the Windows drive was formatted properly as UEFI as it has all four of those partitions. There may have been an issue with the Boot Order, or perhaps the changes I needed to make to the Bios. I wrote that the little "UEFI" icon/label wasn't showing up above the drive's icon in the Boot Order panel and it still doesn't. However, when I looked at the "Boot Override" dialog from the final screen (the one with "Save & Exit" and the other exit options) I noticed that all the drives had the UEFI icon above them. I'm not sure what is causing this discrepancy.

I wanted to list the way some of the Bios options we discussed are now set since things seem to be working. If any of these seem less than optimal or unnecessarily altered please let me know and I will go back and try updating them.

View attachment 513614

FWIW, VT-d has always been locked even though I know that the recommended setting as listed on this site for that feature is "Disabled". I don't know if there's some trick to changing that or if it even matters that much.

Thanks again!

Congrats on the build, @flyingace!! :)

Glad to know you managed to do it, I know how time consuming it is, but also rewarding hehe. I have the same VT-d option listed as it is, running smooth for three years now! As far as I know, there's nothing to worry about anymore. Hope you have a great time with your new macOS :)

Cheers!
 
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Hi Going Bald,

I will soon build a new Hack with Big Sur and W10 on two Nvme's and just wanted to confirm I got everything right to achieve that. Windows will be 1st in the BBS Boot order.
  • Format Windows disk with Mac OS' disk utility
  • Install Windows on the second partition of the disk, leaving the EFI created by disk utility
  • Make BIOS changes for Hack
  • Install Mac OS
  • Put OC on MacOS disk's EFI
  • Select MacOS disk as boot disk in BIOS
Have I missed something?

About CSM: It should be enabled to install Windows but disabled for Hack. If the motherboard I chose comes with CSM disabled as default, should I enable it to instal Windows and then disable it or can I leave it disabled?

Is there anything to do with the EFI folder created with disk utility on the Windows disk once Windows is installed or should I leave it as is?

Obviously, I will not be able to remove the MacOS NVME when installing Windows 10 updates or vice versa, could this create issues?

Is there anything else to do with OC with Bootstrap? In OC installation guide it use to say for Bootstrap to make sure that Bootstrap efi was present and make the following modifications to the plist
  • Misc -> Security -> BootProtect -> Bootstrap
  • UEFI -> Quirks -> RequestBootVarRouting -> True
But this bit seems to have disappeared from the guide. Is it still relevant or are there other modifications needed to the config.plist now?

Thanks a lot!
 
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Hi Going Bald,

I will soon build a new Hack with Big Sur and W10 on two Nvme's and just wanted to confirm I got everything right to achieve that. Windows will be 1st in the BBS Boot order.
  • Format Windows disk with Mac OS' disk utility
  • Install Windows on the second partition of the disk, leaving the EFI created by disk utility
  • Make BIOS changes for Hack
  • Install Mac OS
  • Put OC on MacOS disk's EFI
  • Select MacOS disk as boot disk in BIOS
Have I missed something?

About CSM: It should be enabled to install Windows but disabled for Hack. If the motherboard I chose comes with CSM disabled as default, should I enable it to instal Windows and then disable it or can I leave it disabled?

Is there anything to do with the EFI folder created with disk utility on the Windows disk once Windows is installed or should I leave it as is?

Obviously, I will not be able to remove the MacOS NVME when installing Windows 10 updates or vice versa, could this create issues?

Is there anything else to do with OC with Bootstrap? In OC installation guide it use to say for Bootstrap to make sure that Bootstrap efi was present and make the following modifications to the plist
  • Misc -> Security -> BootProtect -> Bootstrap
  • UEFI -> Quirks -> RequestBootVarRouting -> True
But this bit seems to have disappeared from the guide. Is it still relevant or are there other modifications needed to the config.plist now?

Thanks a lot!
I would suggest that you use the opencore guide to build a usb stick for your particular machine, most if not all the answers you are inquiring about are covered in the guide, I believe bootstrap is no longer relevant. I actually build a completely new USB EFI Folder for each of the major updates to include a new OC version stick. It has worked well and I know it is current to the newest guidance based on the build. Food for though.

Regarding boot order, if you are doing a dual boot (have win and mac on seperate m2 slot nvme drives here) it is not difficult nor does it make any difference to me where that drive falls in the boot order. The Mac drive OC EFI folder is the one that I have load at boot and use the picker to go to windows and if UEFI is how windows was loaded you should be fine.
 
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Thanks for your reply.

Creating OC USB with MacOS is not the issue. It's more about the fact that this guide was written when SATA drives were the thing and you could easily unplug them; with NVMe it's not really an option. Then there is the bit around CSM (enabled to install W10 but disabled to install Mac) and finally what to do with the content in EFI folder created with disk utility on the Windows disk, leave it there?
 
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I have 2 different sized NVME, it wasn't an issue for me to pick the right disk to install on... 1tb for win and 2 for mac so I could pick it easily without fear of installing over a good drive. I installed mac first, then I did the install for the win side. hope that helps. everything was plugged in.
 

Going Bald

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Thanks for your reply.

Creating OC USB with MacOS is not the issue. It's more about the fact that this guide was written when SATA drives were the thing and you could easily unplug them; with NVMe it's not really an option. Then there is the bit around CSM (enabled to install W10 but disabled to install Mac) and finally what to do with the content in EFI folder created with disk utility on the Windows disk, leave it there?
With the new NVMe drives being (usually) under the PCIe cards if installed and hard to remove without disassembling everything I would just leave them in at all times. If you have 2 or more drives installed the procedure is to boot to UEFI/BIOS and set it up for Mac OS. Boot the Win10 install USB and at the screen where it asks you to select a drive, open an elevated command window (Shift+F10) and use diskpart to create an EFI partition, sized 300MB, format FAT32, on the first drive in the list, then create a second partition as a primary, NTFS format, and convert it to GPT. Exit diskpart, exit the command window, select your newly created partition, delete it to free space, click next/continue and allow theWin10 installer to do its work. When complete, do all your setup, update to latest of everything, install your malware apps (I just use MalwareBytes and the Windows Defender included in Win10), install any other third party apps you want and when you have everything set up te way you want it, shut down.

Then boot the Mac install USB and install Mac OS on the other drive. When complete, boot to UEFI/BIOS and set the Mac OS to first in BBS boot order.

Boot Win10 and make sure to delay the feature updates as long as possible and leave the updating on manual - do not set to auto-update. Also set it to notify you when updates are available. When you are ready to update, boot to UEFI/BIOS, set Win10 drive as first in BBS boot order, save&exit, continue boot. Update Windows, restart to complete updates. When done, shut down (do not restart).

Boot to UEFI/BIOS, reset Mac OS drive to first in BBS boot order, save&exit, continue boot. Finished until next Win10 update and then repeat.

If you do not like all of the bloatware in Win10, see the Youtube video by Chris Titus on de-bloating Win10.
 
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I haven't used diskpart for ages :mrgreen: To create the EFI and primary partitions assuming Windows disk is disk 0, I should enter the following commands in diskpart:

list disk
select disk 0
convert gpt
create partition efi size=300
create partition primary
list volume
select efi volume
format fs=fat32 quick
select primary volume
format fs=ntfs quick
Exit

Correct?
 

Going Bald

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I haven't used diskpart for ages :mrgreen: To create the EFI and primary partitions assuming Windows disk is disk 0, I should enter the following commands in diskpart:

list disk
select disk 0
convert gpt
create partition efi size=300
create partition primary
list volume
select efi volume
format fs=fat32 quick
select primary volume
format fs=ntfs quick
Exit

Correct?
that should work
 
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