Re: [gentoo-user] rescue cd for zfs 2.1 or thereabouts

[Michael]

On Tuesday, 31 August 2021 15:33:07 BST Matt Connell (Gmail) wrote:
> On Tue, 2021-08-31 at 10:04 -0400, Rich Freeman wrote:
> > What I probably should get around to is grokking EFI+linux.  I'm not
> > sure what the cleanest solution for that is these days - I've never
> > actually set up EFI on linux, mostly because I'm not sure what the
> > best practice is.
>
> I can't speak to best practices, and I'm a long way from an expert on
> EFI, but the the instructions on the Gentoo handbook pages on disk
> partitioning + grub setup worked as expected for me.
>
> In a small nutshell, you have a small EFI+boot partition, set to type
> 'EFI System' and formatted FAT32, then tell grub to use it as an EFI
> directory when calling grub-install.

In simple(r) systems where you only boot the same OS you can instead use the 
kernel's EFI stub to get the UEFI firmware to load the latest OS kernel 
directly from the ESP, without a 3rd party boot manager:

https://wiki.gentoo.org/wiki/EFI_stub

You'll use the efibootmgr to manage the kernel images stored on ESP, or your 
UEFI configuration menu if it has this functionality.

https://wiki.gentoo.org/wiki/Efibootmgr


If you are multibooting frequently and getting into the UEFI boot menu to 
change the boot order or running efibootmgr is too much hassle, then a 3rd 
party boot manager will be useful.  Your choice of GRUB, rEFInd, systemd-boot, 
syslinux, EFI executable image will be installed and loaded/run by the UEFI 
firwmare from the ESP, with which in turn you will select and load your 
desired OS.

https://wiki.gentoo.org/wiki/GRUB2

http://www.rodsbooks.com/refind/

https://wiki.gentoo.org/wiki/Systemd-boot

https://wiki.syslinux.org/wiki/index.php?title=Install#UEFI