our company has received some Lifebooks for review (e.g. U728). We want to install them in legacy mode since our deployment process requires this.
We have set an Admin PW, then disabled Secure Boot options and enabled CSM.
Everything goes well (loading PXE, loading WinPE, partitioning disk and copying Windows install files) until the windows setup starts. It will then complain about being loaded in UEFI, but not having GPT start partition since our installation process creates an MBR start partition.
So it seems like the CSM does not correctly decide which boot mode to use. I'm aware of other manufacturers who also give you an option to tell CSM which mode (UEFI or Legacy) to try first.
I couldn't find such an option in Lifebook BIOS.