[gentoo-user] Fwd: Installing: Boot partition: /boot or /boot/efi ?

[Alan E. Davis]

Hello:

It's time to try running Gentoo again, after over a decade.

I have gone through, I think, the steps, using the Gentoo LiveCD as a
launchpad.

Installing and configuring Grub has presented a little confusion, regarding
the correct boot partition. I have other GNU/Linux installs on this
machine; for all of them, I've fallen into the practice of setting up grub
in /boot/efi. However, the Gentoo Handbook does not mention this approach,
so I tried using just "/boot". As it turned out, when I
rebooted---thinking all steps had been completed---the Gentoo system does
not appear in the Grub Menu.

I have found that manjaro's grub setup has been good at picking up any
other installs, and, once a particular one has been booted, manjaro's grub
defaults to that other install. Thinking that even if grub is not working,
perhaps Manjaro would see Gentoo, I tried that.

So far, no luck. I am planning to try to mount the boot partition to
/boot/efi, now, and see what happens.

Any problems with this?

Thank you,

[Lee K]

Post by Alan E. Davis
It's time to try running Gentoo again, after over a decade.
I have gone through, I think, the steps, using the Gentoo LiveCD as a
launchpad.
Installing and configuring Grub has presented a little confusion, regarding
the correct boot partition. I have other GNU/Linux installs on this
machine; for all of them, I've fallen into the practice of setting up grub
in /boot/efi. However, the Gentoo Handbook does not mention this approach,
so I tried using just "/boot". As it turned out, when I
rebooted---thinking all steps had been completed---the Gentoo system does
not appear in the Grub Menu.
I have found that manjaro's grub setup has been good at picking up any
other installs, and, once a particular one has been booted, manjaro's grub
defaults to that other install. Thinking that even if grub is not working,
perhaps Manjaro would see Gentoo, I tried that.
So far, no luck. I am planning to try to mount the boot partition to
/boot/efi, now, and see what happens.
Any problems with this?
Thank you,

It should indeed pick it up, if you have properly built your kernel and it
is in the /boot directory. Have you tried running grub-mkconfig manually on
your manjaro distro?

[Michael]

Post by Lee K

Post by Alan E. Davis
It's time to try running Gentoo again, after over a decade.

Welcome back! :-)

Post by Lee K

Post by Alan E. Davis
I have gone through, I think, the steps, using the Gentoo LiveCD as a
launchpad.
Installing and configuring Grub has presented a little confusion, regarding
the correct boot partition. I have other GNU/Linux installs on this
machine; for all of them, I've fallen into the practice of setting up grub
in /boot/efi. However, the Gentoo Handbook does not mention this approach,
so I tried using just "/boot". As it turned out, when I
rebooted---thinking all steps had been completed---the Gentoo system does
not appear in the Grub Menu.

Which GRUB's menu is this? Has it been updated with any new kernels/OS now
available?

Post by Lee K

Post by Alan E. Davis
I have found that manjaro's grub setup has been good at picking up any
other installs, and, once a particular one has been booted, manjaro's grub
defaults to that other install. Thinking that even if grub is not working,
perhaps Manjaro would see Gentoo, I tried that.

Manjaro and other binary distros run the grub-mkconfig command as part of
their kernel & initrd update scripts, whenever a new kernel is installed/
removed. In Gentoo you will need to do this manually AND point it to the
appropriate mountpoint for ESP - see below.

Post by Lee K

Post by Alan E. Davis
So far, no luck. I am planning to try to mount the boot partition to
/boot/efi, now, and see what happens.
Any problems with this?
Thank you,

It should indeed pick it up, if you have properly built your kernel and it
is in the /boot directory. Have you tried running grub-mkconfig manually on
your manjaro distro?

When UEFI MoBos started becoming mainstream and an EFI System Partition (ESP)
with a FAT32 filesystem on it was necessary for UEFI firmware to boot EFI
capable OS/kernels, the convention was to use /boot/efi as a mountpoint
directory to mount the ESP. This would be; e.g.:

/dev/sda1 /boot/efi vfat noauto,noatime 0 2

I understand this is now deprecated and it should be either:

/dev/sda1 /boot vfat noauto,noatime 0 2

or,

/dev/sda1 /efi vfat noauto,noatime 0 2

However, what you call the mountpoint directory in your OS for the ESP is your
choice. It can be named anything you want it to be. What is important is to
adhere to some logical consistency with the UEFI standard, when you store EFI
executables in this mountpoint directory and any subdirectories within it.

The UEFI firmware requires a FAT32 formatted partition, which is created with
type 'ef00' EFI system partition GUID code C12A7328-F81F-11D2-
BA4B-00A0C93EC93B. The UEFI firmware will scan this partition at boot time
and expect to find a directory named \EFI at the root of its FAT32 filesystem,
in which any EFI executables (including GRUB's grubx64.efi) will be stored.
These are conventionally stored inside directories\subdirectories named
according to the different OSs installed on the PC; e.g.

~ $ tree /boot
/boot
├── BOOT
│ └── boot.sdi
└── EFI
├── Boot
│ └── bootx64.efi
├── Gentoo
│ ├── System.map-6.1.12-gentoo
│ ├── System.map-6.1.19-gentoo
│ ├── bootx64-6.1.12-gentoo.efi
│ ├── bootx64-6.1.19-gentoo.efi
│ ├── config-6.1.12-gentoo
│ └── config-6.1.19-gentoo
└── Microsoft
└── Boot
├── BCD
├── BCD.LOG
├── BCD.LOG1
├── BCD.LOG2
├── BOOTSTAT.DAT
[snip]

When you install GRUB in your /boot directory you need to make sure you have
mounted the ESP first and then you point the installer to the appropriate EFI
root directory; i.e.

Either use --efi-directory=/boot, if your ESP mountpoint is /boot;

or --efi-directory=/boot/efi, if your ESP mountpoint is /boot/efi.

Finally, running the grub-mkconfig stanza should pick up all bootable kernels
within the \ESP and update the GRUB configuration file with available kernel
entries.

If you have already installed GRUB via manjaro, you will have the GRUB
executable in the ESP and do not need to reinstall it via Gentoo. As already
mentioned, grub-mkconfig run from within manjaro will probe the boot (and any
other FAT32 formatted) partition and include bootable OS kernels in its
configuration and menu.

With the old /boot/efi mountpoint it used to be the case the /boot directory
was on the root partition, or in any case formatted with a Linux filesystem
which could use symlinks for vmlinuz, but /boot/efi was pointed to the ESP
with its FAT32, where the x64.efi bootloader(s) were installed. When you run
'make install' as part of a new kernel installation the vmlinuz/initrd links
would be refreshed, but GRUB would not know about any of them, until grub-
mkconfig was run again.

HTH.