Q: Where are the UEFI binaries located in Fedora CoreOS 34?

Project Discussion
1

I have been working with FCOS 32 for a while and lost track of the changes happened to FCOS33.
Recently I am trying out the FCOS34 release.

I have installed the fcos.34 using live iso (fedora-coreos-34.20210611.3.0-live.x86_64.iso) in the VMware environment (with efi firmware enabled).
It turns out that I could not see the /boot/efi/EFI/ directory anymore - compared to what I used to see in FCOS 32.

On fcos.32:

# ls /boot/efi/EFI/
BOOT  fedora
# ls /boot/efi/EFI/BOOT/
BOOTX64.EFI  fbx64.efi
#  ls /boot/efi/EFI/fedora/
BOOTX64.CSV  grub.cfg  grubx64.efi  shim.efi     shimx64.efi
fonts  mmx64.efi    shimx64-fedora.efi

On fcos.34 (I do have some errors from sssd.service though, not sure if it’s because the OS was not installed correctly - I will retry and report back.)

# pwd
/boot/efi
# find
.

To compare, I also installed fedora IoT (Fedora-IoT-IoT-ostree-x86_64-34-20210624.0.iso):
fedora.iot:

# ls /boot/efi/EFI/
BOOT  fedora
# ls /boot/efi/EFI/BOOT/
BOOTX64.EFI  fbx64.efi
# ls /boot/efi/EFI/fedora/
BOOTX64.CSV  fonts  grub.cfg  grubx64.efi  mmx64.efi  shim.efi  shimx64.efi

It seems working fine with VMWare.

I don’t understand how UEFI boot works in CoreOS 34.
Could someone explain me what I should expect to see in the fcos.34 installation? Or simply point me to some reading materials so that I could catch up?

Thanks in advance!

2

They are in the second partition. We just don’t mount it in the real root by default because it’s not needed (the system is up and running already):

[core@localhost ~]$ sudo mount /dev/sda2 /boot/efi/
[core@localhost ~]$ find /boot/efi/
/boot/efi/
/boot/efi/EFI
/boot/efi/EFI/BOOT
/boot/efi/EFI/BOOT/BOOTX64.EFI
/boot/efi/EFI/BOOT/fbx64.efi
/boot/efi/EFI/fedora
/boot/efi/EFI/fedora/shim.efi
/boot/efi/EFI/fedora/shimx64.efi
/boot/efi/EFI/fedora/grubx64.efi
/boot/efi/EFI/fedora/BOOTX64.CSV
/boot/efi/EFI/fedora/mmx64.efi
/boot/efi/EFI/fedora/fonts
/boot/efi/EFI/fedora/grub.cfg
3

The other reason we don’t mount it by default is that, if you enable boot disk mirroring with the Butane boot_device.mirror section, there will be an independent EFI system partition on each of the boot disks. In that case there’s no longer a single canonical partition to mount on /boot/efi.

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4

Thanks for the information. It solved my puzzle. :+1:

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