Why does grub menu not show the newly installed kernel in Red Hat Enterprise Linux 6 on UEFI boot based hardware?

Solution Verified - Updated -

Environment

  • IBM System x3650 M3 running in UEFI mode
  • Red Hat Enterprise Linux 6

Issue

  • Why does the grub menu not show the newly installed kernel in Red Hat Enterprise Linux 6 on UEFI boot based hardware?
  • New kernel does not load or show up within grub menu while booting.
  • Red Hat Enterprise Linux 6: After running yum update /boot/grub/grub.conf is updated with new kernel but during boot, grub menu doesn't show it.

Resolution

  • EFI System Partition should be mounted under /boot/efi
  • Considering /dev/sda1 is the EFI System Partition
# mount /dev/sda1 /boot/efi
  • Add the following mount to /etc/fstab so that it persists over a reboot. Find out the UUD of /dev/sda1 by running blkid command.
UUID=FE22-XXXX          /boot/efi               vfat    umask=0077,shortname=winnt 0 0
  • The file /etc/grub.conf should point to /boot/efi/EFI/redhat/grub.conf
# rm /etc/grub.conf
# ln -s  /boot/efi/EFI/redhat/grub.conf /etc/grub.conf
  • Then copy the updated /boot/grub/grub.conf to /boot/efi/EFI/redhat/grub.conf and remove the /boot/grub/grub.conf and mark it as a link.
# cp -f /boot/grub/grub.conf /boot/efi/EFI/redhat/grub.conf
# rm -rf /boot/grub/grub.conf
# ln -s /boot/efi/EFI/redhat/grub.conf /etc/grub.conf

Root Cause

  • In UEFI mode, GRUB reads the /boot/efi/EFI/redhat/grub.conf at the boot time.
  • The file /etc/grub.conf should be symlinked to /boot/efi/EFI/redhat/grub.conf
  • grubby check /etc/grub.conf and adds the new kernel entries to the corresponding grub file.

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