Chainload MBR installtation of Windows in UEFI setup

[Benjamin Tegge]

Suggested enhancement:
If os-prober finds an installation of Windows on a MBR partition, while running in UEFI mode, it should create a UEFI compatible chainload entry and instruct the user to create a valid UEFI boot configuration in Windows, if the files are missing.

Initial situation:
My notebook has two hard drives: a small mSATA SSD which runs Ubuntu 12.10 with UEFI/GPT and a HDD which runs Ubuntu 12.04 and Windows 8 with BIOS/MBR configuration. Running os-prober in UEFI mode on 12.10 detects all installed operating systems but the but the menu entry for Windows does not work because it cannot find the 'drivemap' command and is unable to do 'chainload +1' (error message: not a valid file path/efi image).

Proposed fix:
Configure the entry as UEFI and chainload the efi image (chainload /efi/Microsoft/Boot/bootmgfw.efi). If the image cannot be found in the usual location, os-prober should tell the user to run 'bcdboot C:\Windows /s C: /f UEFI' in Windows, which will copy the necessary files to C:\EFI\ and create a valid BCD configuration.

I have just tested it, Windows can be booted using both methods and there are no modifications to the EFI system partition on the other drive or the partition table on the drive where Windows is installed needed.