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Method for converting legacy Windows install to UEFI for Clover

RehabMan

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This method for converting a legacy Windows install to UEFI works. There may be simpler methods.

This is all on the Probook 4530s.

Here's what I did:
- took the EFI/Microsoft directory from my 4540s running UEFI mode Win8.1 via Clover (copied to USB)
- mounted EFI partition on my 4530s, copied Microsoft directory into EFI
- loaded Ubuntu from USB
- used gparted in Ubuntu to make a simple change, forcing pure GPT. I had Linux on here, so I removed the linuxswap partition, then added it back. That's enough to force conversion to GPT and discarding the hybrid
- rebooted into Clover
- Windows shows up as a possible entry
- attempted to boot it, received errors from the Windows bootloader about a 'missing device'. This is expected, and results from bad BCD data.
- booted into Win8.1 recovery environment and edited BCD by setting device/osdevice entries with BCDEDIT
- rebooted into Clover.
- Windows still there...
- attempted to boot it, no errors this time just a reboot!

At this point it is setup to work, assuming that the Win8.1 UEFI loader can load Win7. Obviously it can't, or at least not with that BCD configuration. At this point, I figure it is worth switching to Win7 UEFI boot loader components.

Note: If you had copied a setup from Win8 and applied it to Win8 (or 8.1) it would work. Or if you had copied a setup from Win7 (UEFI) to Win7, it would also work. My two stage process was just because I was mixing Win8.1 into Win7.

- booted into OS X and mounted the EFI partition
- copied the Win7 UEFI components to the proper places in EFI/Microsoft. (usb)efi\boot\bootx64.efi -> bootmgfw-orig.efi, (usb)\bootmgr.efi->bootmgr.efi (not sure that's even used)
- rebooted into Clover
- selected my Win7 partition from Clover
- success!

Side note: Of course, this breaks my nightly backups as WHS2011 does not support GPT/UEFI setups. Probably time for me to upgrade to WHS2012 anyway...
 

RehabMan

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Having just done this on my desktop, one thing I found interesting is that Windows will boot UEFI to a Windows installed to an MBR disk.

On my desktop, Windows 8.1 was installed legacy to its own disk partitioned MBR. I just did the conversion to UEFI via Clover using the procedure described in post #1 here. I did not convert the drive to GPT, although I plan to do that later.

I was somewhat surprised that I could boot UEFI mode to a MBR partitioned Windows 8.1 originally installed legacy. Of course, the Windows installer will not let you create such a setup, even though it is obviously possible.
 
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In some system, UEFI does not really check for GPT drive, it checks for FAT32 and run .efi file.

Amazing discovery:clap:
 

RehabMan

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In some system, UEFI does not really check for GPT drive, it checks for FAT32 and run .efi file.

Amazing discovery:clap:

I wasn't worried about BIOS as I knew it would run the EFI from a MBR drive (USB drives used by the Windows installer are commonly MBR partitioned). Plus Clover is installed to a GPT partitioned drive and BIOS is running Clover from there... so BIOS is not really involved here... just Clover+Windows.

I was more concerned whether Windows would handle it or cough and choke. But it didn't...
 
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Hi RehabMan,

Amazing "outline"!
Would it be possible to upload your Win8 Efi files? I run on a 4540s so it should work pretty flawlessly I guess.

Thanks
 

RehabMan

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Hi RehabMan,

Amazing "outline"!
Would it be possible to upload your Win8 Efi files? I run on a 4540s so it should work pretty flawlessly I guess.

Thanks

The files are pretty large and the ones you use depend on the version of Windows you have installed. It is probably best that you install Windows (to another partition, or external device) so you can get a copy of the correct files.

Note that much of the tricky work is using BCDEDIT to fix the device/osdevice entries in the BCD file (refer to my multiboot article on my blog, link in signature).
 
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Please Rehabman, do not get mad with me. You know, I am very good at following instructions. Now I migrated to clover in June and my probook has dual boot with windows 7 pro (through Chameleon). Everything works well. The truth is that I do not use windows much, I use Mint in a different laptop. I am afraid I will screw everything and I will not be able to boot at all. This is why I was wondering if anyone else has a suggestion. I am afraid I do not have another computer with windows 8 to follow your suggestions. In any case thank you again for sharing your knowledge.
 

RehabMan

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Please Rehabman, do not get mad with me. You know, I am very good at following instructions. Now I migrated to clover in June and my probook has dual boot with windows 7 pro (through Chameleon). Everything works well. The truth is that I do not use windows much, I use Mint in a different laptop. I am afraid I will screw everything and I will not be able to boot at all. This is why I was wondering if anyone else has a suggestion. I am afraid I do not have another computer with windows 8 to follow your suggestions. In any case thank you again for sharing your knowledge.

It is best to practice on an "exact clone" of your disk.
 
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