[Arie]

That's very interesting, that just made me realize my x299 ITX board has the exact same issue with CSM while trying to boot into OS/X (so also BSD-ish, but hackintosh). So a good chance of hanging on boot, unless I disable CSM and a power loss event will clear this CSM setting.

[drewg123]

This is interesting. FreeBSD has some... deficiencies... in the EFI bootloader's selection of memory to use at boot time. I wonder if the FreeBSD EFI boot loader and your hackintosh boot loader could be trashing the persistent memory where this CSM setting is stored. That might be why it is not a commonly reported issue.