Re: Dual boot - first time using UEFI
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
Re: Dual boot - first time using UEFI
On Mon, May 02, 2022 at 12:44:32PM +0200, Hans wrote: > Hi folks, > > yesterday I installed debian bullseye besides a windows system. As UEFI could > not switched off, I used gparted to make the windows partition smaller. > > Then used an usb-stick and installed bullseye as usual. > > However, the installer discovered UEFI and respected this, but atthe first > boot, only windows could still be booted. > > But the bios allowed me, to boot into windows again (using the F12 key) , and > I could start the installed debian. > > 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). > > After choosing "Do not ask any more", the next reboot showed me the well > known > grub starting screen. > > Well, everything is working, but the problem is: I have nothing learnt of > this! > > 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). > > Thanky for making things clear. > > Best > > Hans > Hello Hans, I think this has also been covered in another thread here. If Windows is the _only_ system on a disk, it hijacks the UEFI booting process slightly :) Most people never notice this because they don't dual boot ever. If you install Debian first, it will install entries into the EFI partition. If you then install Windows, it will set its own EFI entries as first and does not recognise any other operating system. If you have Windows installed first and then install Debian, it _should_ run os-prober and discover that Windows is already there and set it as an entry within grub-efi and Grub's menus. If not, you still end up with Windows first and have to boot using a recovery disk somehow. Rerunning the grub install process at this point does install os-prober and then the system "just works", I think. See also the notes to Richard Owlett about how to dual boot a Debian/ Windows system in the other thread. With every good wish, as ever, Andy Cater > > >
Dual boot - first time using UEFI
Hi folks, yesterday I installed debian bullseye besides a windows system. As UEFI could not switched off, I used gparted to make the windows partition smaller. Then used an usb-stick and installed bullseye as usual. However, the installer discovered UEFI and respected this, but atthe first boot, only windows could still be booted. But the bios allowed me, to boot into windows again (using the F12 key) , and I could start the installed debian. 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). After choosing "Do not ask any more", the next reboot showed me the well known grub starting screen. Well, everything is working, but the problem is: I have nothing learnt of this! 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). Thanky for making things clear. Best Hans
