Long story short, I have an external USB hard drive formatted using a MBR partition table, and I want to install Ubuntu in UEFI mode in a ~23.40 GB unallocated space before a ~442.33 GB NTFS partition that I need to keep:
To install Ubuntu in UEFI mode I need the partition table of the drive to be formatted as gpt.
I don't think there's an easy / direct way to convert a MBR partition table to a gpt partition table, so I'm also looking for the complicated / indirect way.
For example I think something can be done by noting down the NTFS partition start, writing the new partition table and adding the NTFS partition to the new partition table, but I've never done this and I have no idea where to start; furthermore I don't wish to try this for the first time in this case, since I'm not really confident with this stuff and I can't afford losing the NTFS partition I need to keep.