/var like dir accessible early in boot sequence
We need a directory, which is accessible very very early during boot.
It has some files in it which are regenerated at regular intervals, but
not (necessarily) during boot. Actually we know generate it during
runlevels 0 and 6.
For know we put this in /lib/$package. I'm not sure this OK, because it
means we will write to / also when we're not installing
packages. /var/lib seems better, but that is not available that early.
If it is really necessary we could generate the information during
boot, so maybe /lib/init/rw?