I can see OpenSuse in the grub update, but not in the boot menu ; Can somebody help me with that. thanks in advance
If you can see it when GRUB updates, then you probably already have
os-prober enabled. But if one of the discovered entries is not listed in the boot menu, then this is most likely because the operating system in question boots in a different way.
By this, I mean that if your main system boots in UEFI mode, then the one not showing up in the GRUB menu was probably installed for booting in legacy BIOS mode, or vice versa.
As a rule, when installing multiple operating systems on the same drive, they should all use the same method of booting, i.e. either all must boot in native UEFI mode, or all must boot in legacy BIOS mode.
Installing them with different boot modes on separate drives is okay, because then they will use their own boot loader, and then the UEFI boot manager will allow you to select their individual boot loaders. But you cannot mix the two on the same drive, because the UEFI version of GRUB is not compatible with the legacy BIOS version.
The legacy BIOS version of GRUB boots with the processor running in 16-bit real mode, on a single processor core, no hyperthreading and no multitasking enabled, in 1024 KiB of RAM, with direct access to the legacy hardware via the so-called upper memory blocks between the 640 KiB boundary and the 1024 KiB boundary.
The UEFI-native version of GRUB on the other hand is a UEFI executable, running in 64-bit mode with full access to the installed RAM, just like the UEFI itself, and as the 64-bit operating system that you boot from it.
Converting a legacy installation of an operating system into a native UEFI version is possible, but not exactly easy. Therefore, you are probably better off using the UEFI boot manager to boot into openSUSE.
Or, you could reinstall openSUSE in native UEFI mode, but in order to do that, you’ll have to completely disable legacy BIOS emulation (CSM) in the UEFI settings, because most OS installers support booting in either mode, and with CSM enabled, the UEFI will always attempt to boot in legacy mode before attempting a native UEFI boot.
What you see is the result of os-prober scanning the partitions reading the file /etc/os-release.
EFI and BIOS are mutually exclusive - so most likely one is EFI the other is BIOS.
thanks for the info; and is not a big deal for me since I all ready have enough os’s install , this one was just to check it out and not a need .
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