Long story short, I had a single Linux hard drive with a LUKS partitions and stuff which worked really nice for a long time.
Unfortunately, even though Wine nowadays works amazingly well, I couldn't play a few games on my Linux system. And one day, after another Windows feature - "optimus" - broke all of the GPU acceleration after apt-get update, I decided to install a Windows 8 on the second hard drive. Especially, since the license was forced on the new PC anyway - no such thing as OEM Linux PCs :(
So I unplugged the drive, plugged the other one, installed the Windows with UEFI on by default, booted, updated. Replugged back the Linux drive, and now I cannot get them both to work through GRUB without going into BIOS every time.
Linux was installed in legacy mode, but it worked with UEFI option turned on later, Windows 8 was installed in UEFI mode w/o secure boot. Both drives are in a PC. But I can only boot Win if UEFI is on or Linux if UEFI is off.
Is there a way to fix the GRUB? UEFI menu entries?