Hans composed on 2022-05-02 12:44 (UTC+0200): ... > When I got it running, I tried to install grub again onto the MBR, which was > successfull. But now appeared a blue screen, with choices: "Wait 10 seconds - > go on - Restart - Do not ask any more" (similar, is from my remembers). ... > Can ssomebody explain, what technically the grub installer did do? At one > point it said "I have dicovered another EFI partition, shall I use it?" (or > similar, it is from my remembers)....
Grub's job starts differently with GPT and UEFI. The UEFI firmware holds the key to booting, not the MBR. The firmware loads the designated Grub loader, whether that designated and stored in NVRAM, or selected from using the BBS menu, from the ESP, instead of loading MBR code. Installing Grub to MBR should equate to a no-op on a disk used for UEFI booting. The Debian installer may have created a separate ESP rather than using the one that Windows created. It's hard to explain what happened exactly without output from parted -l or fdisk -l or equivalent, both before and after the Debian installation process. Managing which OS controls boot is simpler with UEFI. From Debian boot, it is done with efibootmgr command, but it can be done directly in UEFI setup as well. -- Evolution as taught in public schools is, like religion, based on faith, not based on science. Team OS/2 ** Reg. Linux User #211409 ** a11y rocks! Felix Miata