Tested secure boot lockdown:
root@ibm-gt-opt:~# uname -a Linux ibm-gt-opt 6.5.0-1003-ibm-gt-opt #3~22.04.1-Ubuntu SMP Fri Oct 27 22:48:05 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux root@ibm-gt-opt:~# cat /sys/kernel/security/lockdown none [integrity] confidentiality root@ibm-gt-opt:~# sudo dmesg | grep -i "secure boot" | head -2 [ 0.000000] secureboot: Secure boot enabled [ 0.000000] Kernel is locked down from EFI Secure Boot mode; see man kernel_lockdown.7
Tested secure boot lockdown:
root@ibm-gt-opt:~# uname -a ibm-gt- opt #3~22.04.1-Ubuntu SMP Fri Oct 27 22:48:05 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux security/ lockdown
Linux ibm-gt-opt 6.5.0-1003-
root@ibm-gt-opt:~# cat /sys/kernel/
none [integrity] confidentiality
root@ibm-gt-opt:~# sudo dmesg | grep -i "secure boot" | head -2
[ 0.000000] secureboot: Secure boot enabled
[ 0.000000] Kernel is locked down from EFI Secure Boot mode; see man kernel_lockdown.7