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List:       gentoo-user
Subject:    Re: [gentoo-user] updating /boot directory EFI
From:       thelma () sys-concept ! com
Date:       2023-04-16 17:39:16
Message-ID: a500bc2e-5f22-697e-ce85-3ef03b3533b9 () sys-concept ! com
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On 4/16/23 05:16, Mitch D. wrote:
> When you emerge grub, Gentoo compiles and "installs" grub (and some grub-related \
> tools) to a directory inside your Gentoo installation, just like other \
> applications. The catch is that grub isn't like other applications... it needs to \
> run outside of Gentoo, before Linux starts. This means that Grub isn't very useful \
> sitting inside your Gentoo installation. 
> "grub-install" copies Grub from your Gentoo installation to your hard drive / SSD / \
> etc. This has nothing to do with your kernel, it only involves Grub. Rerun this \
> command when you emerge updates to Grub. 
> "efibootmgr" tells your motherboard's (U)EFI firmware where to find Grub (or any \
> other bootloader or EFI tool). When you emerge an update for Grub (and run \
> grub-install), the path shouldn't change, so there's no need to rerun efibootmgr. \
> This also has nothing to do with your kernel. 
> "grub-mkconfig" generates a configuration file that Grub reads while the computer \
> is booting, and generally tells Grub what options to include in the menu Grub \
> displays. When you update your kernel, you want to update that menu, so you SHOULD \
> rerun "grub-mkconfig" at this time. 
> All EFI systems are supposed to have an EFI system partition (ESP). Some people use \
> the ESP as their boot partition, while other people keep them as two separate \
> partitions and mount the boot partition as /boot and the ESP as /boot/EFI. Either \
> way, it's not related to dual-booting. 
> NOTE: if I remember correctly, there are USE flags that can be enabled to \
> automatically run grub-install and grub-mkconfig when updates are installed for \
> Grub and for kernels, respectively. 
> -Hypoon
> 
> On Sun, Apr 16, 2023, 00:19 <thelma@sys-concept.com \
> <mailto:thelma@sys-concept.com>> wrote: 
> On 4/15/23 22:01, thelma@sys-concept.com <mailto:thelma@sys-concept.com> wrote:
> > After installing new kernel how to update /boot EFI directory?
> > 
> > From my notes, I have:
> > grub-mkconfig -o /boot/grub/grub.cfg
> > grub-install --target=x86_64-efi --efi-directory=/boot
> > 
> > or should it be:
> > grub-mkconfig -o /boot/grub/grub.cfg
> > efibootmgr -c -d /dev/nvme0n1p1 -p 1 -L "Gentoo" -l \
> > /boot/grub/x86_64-efi/core.efi 
> > Boot partition is:
> > /dev/nvme0n1p1   =  /boot
> 
> This is not dual boot system, so I don't know why /boot has EFI directory

Thank you Hypoon and folks for detail explanation.  Always learn something new.
So once EFI is installed during grub installation there is no need to touch it, by \
running:

grub-install --target=x86_64-efi --efi-directory=/boot

And thanks Lee for a hint about booting kernel manually from grub command line.
I'll definitely look it up and make some notes.
Anybody can share more information on it.

And NO, I'll not look check ChatGPT, don't want to end up with unbootable system :-)


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