I am almost certain that this has been asked before, and I am almost sure that the answer is "no, that would be silly", but I can't find anything in the archives, in :help or on Google in general. I am suffering the aftereffects of a bout of flu today, so perhaps I'm just being bad at searching.
Basically, is there any (easy) way of preserving the undo stack between sessions? I typically work with half a dozen tabs and 20-30 files open at any one time and whenever I need to reboot my machine then I do a :mksession and reload it when I come back. It is ridiculously useful, but I would love if the undo was stored too. Cheers, and sorry for asking this over-asked question again. Max