Thanks, but this doesn't really address my actual concern (which I probably should have made more clearer).
Let's say I set my firmware password to "somePasswordThatIAlsoUseInALotOfOtherPlaces".
Is it possible somehow for a hacker to obtain this plain text password from the firmware, if he has physical access to the computer? To understand this, we have to understand how the password is actually stored in the firmware.