Make buildworld and reboot

[Bnonn]

Hi everyone.

I recently let a make buildworld run overnight following updating
source, and came back in the morning to find that the process had
completed successfully, but that my keyboard had gone completely dead. I
don't know why this happened, but it might have something to do with
having a USB keyboard. Anyway, I couldn't run make installworld
following this since the keyboard was no-go, so I was forced to
hard-reboot.

Not knowing a great deal about what make buildworld really does, I'm not
sure if the changes it effects are persistent through a reboot. Do I
need to run make buildworld again before running make installworld? I've
skimmed the manpages on make, but they seem directed to the sort of
people who want to create makefiles, rather than just run them, and I
thought I could probably get the quick and dirty answer here without
having to resort to three days of study :)

Your help is appreciated

Bnonn