Re: [gentoo-user] UEFI boot [FIXED]

[Mick]

On Saturday, 26 October 2019 12:36:56 BST Peter Humphrey wrote:
> On Friday, 25 October 2019 16:33:07 BST Mick wrote:
> > If you intend to have a list of available OS kernels displayed for you to
> > choose from at boot time, then you need a Boot Manager (eLILO, GRUB,
> > systemd- boot, et al.) and will *have* to follow the respective Boot
> > Manager's conventions regarding its configuration and storage/naming of
> > kernel images.
>
> That's the key. It's clear that I haven't understood what was going on until
> now. Mind you, I've not been helped by the plethora of mutually
> contradictory wiki and other articles purporting to guide me through the
> boot process - for instance, should my boot partition (FAT32) be mounted on
> /efi, /boot or /boot/efi? All are recommended in various places. Mine is on
> /boot.

Your $BOOT partition should be set as type ESP (i.e. with GUID C12A7328-
F81F-11D2-BA4B-00A0C93EC93B), or as 'Linux Extended Boot' (GUID 
BC13C2FF-59E6-4262-A352-B275FD6F7172),[1] as long as this is a disk with a GPT 
rather than MBR partition table.

[1] The 'Linux Extended Boot' partition type as called by fdisk is typically 
used when the ESP is too small to contain all OS kernels, Boot Manager files 
and UEFI applications.  You'll need to set the ESP partition type using a 
partition manager, like gdisk, parted, fdisk.

The filesystem on $BOOT should be FAT32 (although it can be FAT12, or FAT16).

The $BOOT partition should be mounted on mountpoint /boot.

In its filesystem-root, boot/ should have a directory EFI/, i.e. /boot/EFI.  
Any OS system kernel images you expect the UEFI boot manager to autodetect and 
list in its own firmware/BIOS GUI should be added in /boot/EFI/, each one in a 
separate subdirectory suitably named to identify the OS.

In boot/EFI should also be the subdirectory boot/EFI/BOOT/, in which the 
default fall-back OS kernel image should be stored.  The UEFI boot manager 
will boot this kernel image if other kernel images fail to boot.  Removable 
devices can have more than one subdirectory with a kernel image in them, in 
boot/EFI/BOOT/, to automatically boot one of them.

The above is no gospel, indeed some binary distros install /boot/efi/EFI and 
drop their Boot Manager's grubX64.efi in some suitably named subdirectory in 
there, but you get the gist.


> To sum up: I didn't need efibootmgr at all, except to remove an entry I'd
> created before. I did need bootctl from sys-boot/systemd-boot, and I had to
> 'bootctl install' it without any configuration files under /boot. I also
> needed a machine ID in /etc/machine-id, without which 'bootctl install'
> refused to do anything.

systemd-boot uses the machine-id[2] in its nomenclature for each OS installed 
on this hardware and it also creates a correspondingly named subdirectory 
within /boot/ for OS kernel images and associated files to be dropped in there 
by binary distros' kernel installer scripts.  Without a machine-id I would 
think systemd-boot would cough loudly when you try to install it, just as you 
report.  The same machine-id is subsequently used for the naming of .conf 
files for each OS/kernel - see below.

[2] If there is no /etc/machine-id check for /var/lib/dbus/machine-id.  The 
machine-id is generated at install time, by dbus.  On my system /var/lib/dbus/
machine-id is a symlink to /etc/machine-id.


> The procedure was:
>
> 1.  Format /dev/nvme0n1p2 as FAT32 and mount it on /boot.
> 2.  Build and install the kernel.
> 3.  Run bootctl install.
> 4.  Write /boot/loader/loader.conf, and suitable .conf files under
>     /boot/loader/entries.
>
> That still left an empty /boot/<machine-id> directory. I may risk removing
> it some time.

I wouldn't do such a thing, but YMMV.  If your intention is to use systemd-
boot as the Boot Manager of choice, I would try moving all kernels and 
associated files to your /boot/<machine-id>/ subdirectory.

Then create corresponding /boot/loader/entries/*.conf files, which according 
to the systemd boot loader specification should be named like so:

/boot/loader/entries/4eec63dc92f83de25e1e2e485d7f6536-4.19.72-gentoo.conf

/boot/loader/entries/<machine-id>-<kernel_version>.<os-release-ID>.conf

For <kernel_version> use the output of 'uname -r'.

For <os-release-ID> use the ID field of /etc/os-release.  You may 'find uname 
-r' and os-release-ID are the same on your Gentoo installation.

The contents of the file should look like so:

title        08-gentoo-4.19.72-rescue (My rescue kernel)
version      4.19.72-gentoo
machine-id   4eec63dc92f83de25e1e2e485d7f6536
options      root=/dev/nvme0n1p4 net.ifnames=0
architecture x64
linux        /4eec63dc92f83de25e1e2e485d7f6536/4.19.72-gentoo/linux
initrd       /4eec63dc92f83de25e1e2e485d7f6536/4.19.72-gentoo/initrd

For 'title' you can use the PRETTY_NAME in /etc/os-release, or whatever you 
want displayed in the boot menu to differentiate visibly this menu entry from 
all others.

For 'version' you can use the kernel version you want to boot with, but it is 
an optional field.

Machine-id is also optional, but it helps to differentiate between various 
installations.

'linux' and 'initrd' fields show the relative path(s) where your vmlinuz and 
initrd.img files are stored.

I hope the above works for you with systemd-boot and helps customise its boot 
menu to your liking.

-- 
Regards,

Mick