[cool_beanz]

>I need the flexibity to boot different OS kernels. AFAIK, UEFI offers no such flexibility.

Yes it does, I use it with two kernels, just have different entry for each stub in UEFI. Whenever I want to boot the non-default kernel I just hit F11 (for BIOS boot menu, on my motherboard) and choose the boot option. You just need to add the boot options in UEFI, pointing to the corresponding EFI files. They also have the kernel command line parameters baked into them and you can set your desired ones (silent boot whatever).

[1vuio0pswjnm7]

Thank you.

[fuzzfactor]

You can also craft a text file named startup.nsh, and if present in the root (or ~nearby) of the FAT32 EFI partition, on bootup its UEFI commands will be executed rather than the default firmware selection.

If a motherboard doesn't have enough UEFI commands in its built-in Shell (or has no built-in Shell at all), you'll want to include your own Shell.efi file right there along with any startup.nsh you might decide to deploy.

This can also be good for USB booting where the removable USB device is in regular MBR layout rather than GPT-style-partitioning.

Whether or not the whole USB drive is FAT32 or not, as long as there is a proper EFI folder in a UEFI-recognizable filesystem, you can boot to any other OS on any other filesystem, depending only on the contents of the EFI folder. Unless there is a startup.nsh for the UEFI to follow instead, then you might not even need an EFI folder. As intended. Boot floppies still work as designed too. Startup.nsh is more commonly expected to contain reference to an EFI folder that is present on some recognizable filesystem, rather than work as a lone soldier though. GPT-layout partitions are not supposed to be necessary either, it's only needed when you want more partitions than legacy BIOS will handle, or partitions that are too huge for MBR representation.

Now any alternative to GRUB would by necessity have to perform more pleasingly on legacy-compatible systems where UEFI is not enabled also, or it will remain a less-effective alternative.

Once a geek is smart enough to handle both BIOS & UEFI, the more I would be able to trust their UEFI solution.