I have a dual boot laptop Windows 10 / Linux mint 20. Secure boot enabled and also hard disk encryption, but the latter is maybe not important for the question.
By the way, my question is very similar to this one: https://forums.linuxmint.com/viewtopic.php?t=274365
I installed Windows and after that - Linux Mint. After Mint installation, computer rebooted and I was asked to "Continue boot" or "Enroll MOK". I didn't know what to do and went to search online on the other laptop. While searching, the dialog apparently timed out and the computer just continued booting. Laptop is Dell Vostro 5581 updated to latest BIOS.
Later on the same day, I installed Virtualbox from Oracle's web site (not from repository). During the installation in text mode on the console it asked me to confirm that I want to enroll MOK upon the next reboot and enter a temporary password. I did and rebooted and enrolled the MOK. (Not knowing what I am doing, by the way)
So, here are my questions. All this secure boot thing is very new to me.
What is the initial "Continue boot" or "Enroll MOK" dialog that appears when you install Mint and reboot for the first time? This appears before the OS even boots. I think it's a BIOS thing. And it seems to does not matter if you just continue boot or enroll the key. I did 2 Linux installations and in the 1-st one I chose to enroll the key, but on the 2-nd ignored it. There seemed to be no difference.
If I had enrolled the MOK key, would Virtualbox have installed without asking me to do anything? What exactly does VirtualBox when it enrolls its own key?
How can I do the "Enroll MOK" now after I have installed and configured my system and really don't want to re-install again? The other question on the forum (see link above) has an answer saying:
I had the same problem. In order to set a new MOK password I've used the command
sudo update-secureboot-policy --enroll-key
however, on my installation there is no such command
Now I am afraid to install the proprietary NVidia drivers, because I didn't enroll MOK and am afraid that it won't work.
And, generally, what does this "Enroll MOK" thing do after the 1-st reboot? I really don't understand it. Does it mean that it puts some Ubuntu keys in the BIOS? Does it mean that if I do it, then all future proprietary kernel modules that I install will happen smoothly without enrolling their own MOKs?