Comment 4 for bug 2046500

Calamares detects what firmware the system is using though. If you're on an EFI system, it's fine if a GPT partition table is left intact, but very bad if an MSDOS one is left (I believe). Calamares, to my awareness, always makes an MBR table on BIOS systems, and a GPT one on EFI systems. That's correct behavior as far as I can tell.

The only way this could be faked out AFAIK is to boot the installer in the wrong mode (booting in BIOS mode on an EFI system by selecting a legacy boot option, or booting in EFI mode on a system you wanted to use in legacy mode). This is certainly possible, but this causes problems with flavors other than Lubuntu too. It's always a bad idea to install like that.

I personally am rather surprised that Ubiquity and Subiquity *don't* erase partition tables. I'm sure it's intentional, and I guess it doesn't appear to cause problems for some people, but the idea of "erase disk" not truly erasing the whole disk is slightly alarming to me.

In any event, if someone can provide a reliable set of steps that allows fooling Calamares into installing Lubuntu into an MBR partition table when booted in EFI mode, or installing into an improperly created GPT partition table (one missing a bios-boot partition) when booted in BIOS mode, then I think this is worth looking into. Until then though, I'm inclined to say this is intentional behavior. If a user truly wants something other than the default, that's what manual partitioning is for. (I'm not the one who makes the final decision on whether or not this is going to be worked on, but right now I just don't see why it needs changed.)