OK so I have quite a complicated setup. I am using Windows 10 and because my setup is so old (that is, the boot drive since I upgraded from Windows 7, not the actual computer components), Windows is in Legacy mode using MBR. I have Windows installed on a 250 GB SSD and it is not sharing any other partitions or operating systems. I also have another 120 GB SSD which I formatted completely for installing Linux. My motherboard supports both UEFI and BIOS.
Now when I installed Antergos to this 120 GB drive, it chose UEFI mode. The problem is I want to be able to dual boot into Windows without having to go into UEFI/BIOS and changing the boot device every time. So I read that you can’t have mixed mode with GRUB, therefore I went about converting the installation to use BIOS. I used the built-in Disks application to change the boot partition to be BIOS instead of UEFI, and also ticked “Legacy bootable” box for both the boot and OS partitions. I re-built my GRUB and installed it, no issues.
Finally, the option I put in my custom40 file for booting non-EFI Windows showed up! Albeit GRUB was in super-low resolution mode, so everything looked huge on my 4K monitor. Anyways I chose Antergos and it didn’t work. There were some strange numbers and I presume somehow the section where the OS needs to start booting from is hard-coded or something like that, since I just get some progress timer that goes to 1 min 30 seconds every time I boot.
Anyways, I have no idea what’s going on or how to fix it. Do I need to re-install Antergos or is there some way to fix this?