Never tested myself, but I've been told by reliable sources that Windows has such a limitation, both directions. Won't permit install in UEFI mode to MBR, nor BIOS mode to GPT (even with a BIOS boot partition).I wonder if "UEFI requires GPT" is actually a Windows (10/11) limitation
As it happens, I learned an EFI partition works with MBR inadvertently. Was scenario testing a bug in the Ubuntu 22.04 installer (since fixed), which in automatic mode insisted on creating a superfluous EFI partition, even when dual booting with a pre-existing BIOS system on MBR. For grins, switched to EFI mode (in VirtualBox) and to my surprise found the VM would boot. The crucial thing, apparently, is the boot flag (and the EFI partition being formatted Fat32).
Anyhoo, congratulations @Jeremy Davis for a successful resolution.
Statistics: Posted by pbear — 2024-01-04 02:10 — Replies 16 — Views 288