I’ve been using Manjaro for what seems like a thousand years, and haven’t had the need to reinstall for maybe 2 years. Anyway, long short short: my install got borked, so I’ve been attempting to do a clean install. Except things have changed since my last install.
I dual boot Windows 10 + Manjaro, and what I used to do was burn the ISO to a thumbdrive, start the boot process, hit F8 on my ASUS mobo so as to bring up and choose the non-UEFI option from the menu, load up the live environment, choose my partitions, make sure I have my SSD drive set as the GRUB destination, hit install, and I was done.
This time around, on choosing install, up pops a message telling me a GPT partition is best, and that I have to create an 8 MB unformatted partition to start Manjaro on a BIOS system.
Has something fundamentally changed. or is there a way I can just reinstall Manjaro as I used to without faffing about with GPT and creating extra partitions?
No, you should normally still be able to install Manjaro in legacy BIOS emulation mode, and on an MBR-partitioned drive. This type of installation is still supported, and I reckon it’s not going to go away any time soon.
The message is purely informative; it is teling you that GPT is better — which is true, because GPT is more robust — and it is telling you that if you opt for GPT in an installation that boots in legacy BIOS emulation mode, then you should create an unformatted partition of type bios_grub, and with the boot flag set. This is because the legacy BIOS boot version of GRUB would otherwise overwrite your partition boundaries and damage your filesystem. But this is not required on an MBR-partitioned drive, and a native UEFI installation of GRUB uses the dedicated EFI partition anyway.