- check all lines with XXXY

- check all thread exits: free mem

- make ddekit (lib/include/{dde_gate,dde_intern} lib/common/dde)
  a package (l4/pkg/ddekit); dde_gate should be called ddekit then

- ddekit: provide function to disconnect from an interrupt

- fbsd condition variables (lib/common/bsd/modified/kern/kern_condvar.c)
  can also be used from contrib; self-implementation not neccessary
  -> performance impact?

- fbsd semaphores (lib/common/bsd/contrib/kern/kern_sema.c):
  is direct mapping to dde semaphores faster?

- check performance: inline vs called ddekit semaphores
