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Guide: Multibooting UEFI on Separate Drives

Going Bald

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Thank you very much for your prompt reply.

Yes there is an EFI partition on the Win10 drive. I just mounted it from OS X using Clover Configurator and verified that it has an EFI directory in which are two directories, Boot & Microsoft.

I did. I disconnected all other drives while I was installing Win10 as per the recommendation at the beginning of this tutorial.

The icon in Clover has the Win10 drive labeled as "Boot Microsoft EFI Boot from EFI."

Again, thank you for your help with this. I will try to answer any further questions promptly.
Have you disabled CSM in BIOS/UEFI?
 
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CSM was not disabled in BIOS. It was locked on "Always" but after I switched whatever the OS switch just above it was from "Other OS" to "Windows 8" it became accessible and I switched it over to Disabled. I then switched the OS switch back over to "Other OS". The menu that asks whether I want to be able to boot "UEFI Only/UEFI and Legacy/Legacy Only" had been set at "UEFI Only" when I made these changes. Now that CSM is disabled that menu is no longer accessible and it's locked on "UEFI Only." No idea whether this is important or not.

When I look at the Boot order on the first screen of the BiOS I noted that none of the icons that represented the Windows drive had the little UEFI icon above them as some of the others did. But I thought I had installed Windows 10 as UEFI. Could I be easily mistaken on that point?

After making the changes I've made above I rebooted the machine and tried to boot into Windows 10 from Clover. First I got the little wheel of spinning balls and soon "Preparing Automatic Repair" appeared, then "Diagnosing Your PC" and finally the screen that says "Your computer didn't start properly" and the options to restart or to try to fix the thing. So I restarted and when I got to Clover tried again to boot Windows 10. This time no messages, just the spinning balls wheel and then a black screen and the power light on my monitor blinking as it does when it's not getting any content.
 
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Going Bald

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CSM was not disabled in BIOS. It was locked on "Always" but after I switched whatever the OS switch just above it was from "Other OS" to "Windows 8" it became accessible and I switched it over to Disabled. I then switched the OS switch back over to "Other OS". The menu that asks whether I want to be able to boot "UEFI Only/UEFI and Legacy/Legacy Only" had been set at "UEFI Only" when I made these changes. Now that CSM is disabled that menu is no longer accessible and it's locked on "UEFI Only." No idea whether this is important or not.

When I look at the Boot order on the first screen of the BiOS I noted that none of the icons that represented the Windows drive had the little UEFI icon above them as some of the others did. But I thought I had installed Windows 10 as UEFI. Could I be easily mistaken on that point?

After making the changes I've made above I rebooted the machine and tried to boot into Windows 10 from Clover. First I got the little wheel of spinning balls and soon "Preparing Automatic Repair" appeared, then "Diagnosing Your PC" and finally the screen that says "Your computer didn't start properly" and the options to restart or to try to fix the thing. So I restarted and when I got to Clover tried again to boot Windows 10. This time no messages, just the spinning balls wheel and then a black screen and the power light on my monitor blinking as it does when it's not getting any content.
Sound as if Win10 was not properly installed UEFI mode.
If Win10 installs UEFI mode there are 4 partitions
Partition 1 = Recovery
Partition 2 = EFI
Partition 3 = Microsoft Reserved (MSR)
Partition 4 = Primary Partition (C:\)
 
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I apologize in advance as this question has likely been answered already. I want to be able to launch both Windows 10 and OS X Mojave (10.14.6) from this computer. I've had Mojave running without issue for some time, launching from Clover at startup etc. I recently added a new hard drive and followed the steps outlined at the beginning of this thread for making a Windows 10 drive. I see a Windows 10 drive in the Clover launch window but it takes me to a blinking cursor on a black screen and then nothing. I can launch Windows 10 by selecting F12 at startup and selecting the drive in the menu thereafter.

When I say I followed the instructions at the beginning of the article I mean that I followed them for Windows installation. I did nothing to my OS X driver thereafter.

If this question has been answered previously (I've tried to find an answer but 5 years is a lot of posts to sort through) and someone can point me there I'm happy to try to follow whatever instructions have been previously offered.

Many thanks.

Hey flyingace, just saw your posts on both threads. I know how you feel, been there!

I'm aware this might be a silly question, but we know much of these processes are so complex we might forget to watch for the little things. What USB stick are you using? Have you tried using another one? I've had similar non-successful trials that ended up being caused by an USB 3.0 pendrive. I finally made another Windows installation disk on Rufus with a common stick, and voilà.

I run a smooth dualboot Win10 & Mojave on a Gigabyte mobo also, booting through Clover. Let me know if it helps :)
 
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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.

IMG_20210324_190658708_HDR.jpg


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!
 
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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.
 
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