Dipsitck dry - or what is the minium oil amount needed for the engine to survive?:)

[Sumi]

So here is the deal:

I've been overlooking the regular maintenance on my 950 ADV lately.. And by regular I mean daily:) So I've came out of the habbit checking the oil level after every ride (it's dark and cold outside when I get home, and yeah.. blabla). Anyway, when I checked it today (properly!), the dipstick was dry.. After a mini heart attack, I've filled it up with half a liter, and now it is at the 1/3rd of the stick..

So my question would be: is it possible that engine damage occured?
I can't hear any unusual sounds from the engine, shifting is perfect, and the oil light wasn't flickering or on (if this even means anything in this situation) so I suppose it survived.. Does anybody have an idea about the minimum oil amount required to avoid engine damage? If my calculations are correct, I had about 2-2.2L in the system.. but I guess I can't be sure about any damage until an oil change / valve inspection..

Thanks for the answers!