Re: [gentoo-user] Boot and EFI partitions

[Victor Ivanov <vic.m.ivanov@gmail.com>]

On Wed, 6 Dec 2023 at 17:35, Marco Rebhan <me@dblsaiko.net> wrote:
> No, you do not need an XBOOTLDR partition with systemd-boot and in fact I have
> never used one, and I'm not sure why the guide advertises it so prominently.
>
Good to know! Then I'm not sure why the guide is advocating for one if
they're both FAT32. And, as I mentioned earlier, the Boot Loader
Specification doc does suggest that it's optional, so I would have
been surprised if any implementation would require the partition.

> There seems to be a lot of cargo cult around boot partitions (probably left
> over from the BIOS days), you really only need the ESP. The set up I have used
> for years is ESP at /boot, containing systemd-boot, kernel, initramfs and so
> on, and that's it (excluding of course / and other actual system partitions).
>
I disagree that it's _just_ BIOS days thing. While you can,
irrespective of boot loader, have all of your kernel and initrd images
dumped into ESP without any functional issues and do away with a
separate partition, there are benefits to the contrary. One such
benefit is journaling. Unless your EFI firmware allows for a non-FAT32
ESP, then storing the kernel and initrd images will need to be on a
separate partition.

While data corruption during write operations on this partition, given
its usage patterns, is perhaps highly improbable it's certainly not
impossible. So while the benefits of a journaling system for /boot may
be small, they can be a legitimate consideration.

In this line of reasoning, perhaps the boot loader guide(s),
particularly the one in the Handbook, are aimed at covering a
partition layout that:
a) is compatible between EFI and BIOS set ups (with difference being ESP);
b) is consistent across boot loader choices and compatible enough if
one should wish to switch from one to the other at a later point;
c) allows for cases where rootfs may not be readable by a boot loader
(e.g. encryption as previously mentioned); and
d) offers a degree of protection from corruption on writes;

while leaving the coverage various possible layout choices to those
that are more familiar with what they're doing. So some of it may be
baggage from BIOS days, I admin, I also would not be surprised if it
was a conscious decision to reduce the complexity of a first-time set
up by someone new to Gentoo. A 50+ page document, while exhaustive,
certainly wouldn't classify as a "handbook" or something to use as a
reference.

Regards,
Victor