On some of the last Posts in the topic GRUB4DOS for UEFI the user zammibro was talking about UEFI booting on a only Bios PC and I said it was not possible as Bios programs do not have the required code and internal drivers to boot on UEFI environment on this Post, but our friend Wonko made a very simple and clear explanation of how Clover works in order to UEFI boot on a only Bios (or CSM) PC on this Post. And also mentioned some links to AIO_Boot pages with additional info on this Post.
Well, let me tell you I have used AIO_Boot since very long time ago, in fact I'm the Spanish translator, but never used Clover before as I had the idea it was only a tool to boot Apple OS on a PC.
Then I decided to run some test to see if Clover was really capable to UEFI booting on a only Bios PC a Windows installed on our internal HD, (MB used for this tests is Gigabyte GA-G41MT-S2 v1).
I went to AIO_Boot download page and downloaded last version, and installed it on a USB device as usuall.
Then ran the AIOCreator.exe to integrate my Win10XPE_x64 and my 7pe_amd64_E on AIO-Boot USB device, after booting from it both booted fine as UEFI. To make sure about this I ran BootIce v220.127.116.11 2015-02-16 from both WinPEs and opened UEFI Tab, and the option to edit the UEFI boot entries was available. It was a little weird as we all know 7x64 is not fully capable to boot on UEFI environment. Then this test demonstrated Clover is capable to provide the required code and internal drivers to boot on UEFI environment a Windows PE. But it didn't work when I tried to UEFI boot a Win10 Pro x64 installed on my internal HD.
In order to keep safe my multiboot on the internal HD, I switched off the PC and connected an spare Sata drive to run the following tests, booted Win10XPE_x64 from AIO-Boot to repartition and format the drive (MBR partitioned), I made a 5 GB first active primary partition FAT-32 (to have espace just in case but 1 GB should be enough), and a 40 GB NTFS second primary partition and cloned into it the Win10 Pro x64 drive/partition from the internal HD, also made an extended partition on the rest of the drive and cloned on a logical partition my Programs drive/partition to have available all my tools, then I created all bootable files/folders by command line on the FAT-32 first partition:
bcdboot C:\Windows /s S: /f ALLWhere:
C:\Windows = Where Win is installed (just change C: for the drive letter where Windows is installed as seen on the WinPE)
/s S:: = Where the boot files/folders will be installed (just change S: for the letter of your System Reserved partition as seen on the WinPE)
/f ALL Installs MBR + UEFI boot files/folders
And switched off the PC again to disconnect the other HD.
Booted again from AIO_boot USB stick, and this time as the standard EFI folder with all files/folders to UEFI boot the Win10 Pro x64 OS is available on FAT-32 partition the system was able to boot fine on a Clover emulated UEFI environment.
See attached photos of Clover options selected and also the probe by means of BootIce that it was really booted on UEFI environment.
Then I have to recognize that it is in fact possible to UEFI boot on a only Bios PC, by means of AIO_boot and Clover.