Kernel isn't booting once CloudLinux is installed on Dell Servers (AlmaLinux/RockyLinux)

Issue

Your DELL server is unable to boot from UEFI partition once you have converted Almalinux\RockyLinux to CloudLinux.

Environment

• AlmaLinux/RockyLinux
• CloudLinux
• Dell servers (only a few specific Dell servers)

Solution

In case your server is still UP after conversion and you didn't reboot it yet, do:

cp -rp /boot/efi/EFI/centos/* /boot/efi/EFI/almalinux/

In case the server is already not booting:

Boot AlmaLinux 8 or CentOS 8 LiveCD. In the boot menu, choose Troubleshooting:

Then "Rescue an Almalinux system" or "Rescue a CentOS system" if you are running CentOS live CD:

When requested, if the system needs to be mounted, type "1" and press "Enter"

Press "Enter" again on a prompt to shell:

Type "chroot /mnt/sysroot" end press "Enter":

Type "cp -rp /boot/efi/EFI/centos/* /boot/efi/EFI/almalinux/" press "Enter" and then you can reboot.

In addition to the solution described above, on the servers where the fix was manually applied you also need to do the following:
- if /boot/efi is located on the usual disk partition (like /dev/sda1):

device="$(df -T /boot/efi | sed -n 2p | awk '{ print $1}')"
disk_name="$(echo "${device}" | sed -re 's/(p|)[0-9]$//g')"
disk_num="$(echo "${device}" | tail -c 2|sed 's|[^0-9]||g')"
efibootmgr -c -L "CloudLinux" -l "\EFI\centos\shimx64.efi" -d "${disk_name}" -p "${disk_num}"

- if /boot/efi is located on raid1 (/dev/md*) (raid1 only supported):

device="$(df -T /boot/efi | sed -n 2p | awk '{ print $1}')"
soft_dev1="$(cat /proc/mdstat | grep "${device:5} " | awk '{ print $5}' | head -c -4)"
soft_dev2="$(cat /proc/mdstat | grep "${device:5} " | awk '{ print $6}' | head -c -4)"
echo "$soft_dev1"
echo "$soft_dev2"
disk_name1="$(echo "${soft_dev1}" | sed -re 's/(p|)[0-9]$//g')"
disk_name2="$(echo "${soft_dev2}" | sed -re 's/(p|)[0-9]$//g')"
disk_num1="$(echo "${soft_dev1}" | tail -c 2|sed 's|[^0-9]||g')"
disk_num2="$(echo "${soft_dev2}" | tail -c 2|sed 's|[^0-9]||g')"

# before next 2 commands, please cross-check manually that disk_name* and disk_num* contain proper disk names and partition numbers for /boot/efi

efibootmgr -c -L "CloudLinux" -l "\EFI\centos\shimx64.efi" -d "${disk_name1}" -p "${disk_num1}"
efibootmgr -c -L "CloudLinux" -l "\EFI\centos\shimx64.efi" -d "${disk_name2}" -p "${disk_num2}"

Cause

The conversion of Almalinux to Cloudlinux moving bootloader to /boot/efi/EFI/centos directory but on DELL's - new bootloader configuration is not detected on some DELL servers. The root cause is being investigated.