* empty the queue of frames in the mmap frame buffer and set the   index of the current frame to -1 when the mmap frame buffer is free'd * set the index of the current frame to 0 when allocating the mmap   frame buffer * paranoia: panic if a) the mmap frame buffer is already allocated when   we try to allocate it, or b) the mmap frame buffer is not allocated when   we try to add frames to it
* empty the queue of frames in the mmap frame buffer and set the
  index of the current frame to -1 when the mmap frame buffer is free'd
* set the index of the current frame to 0 when allocating the mmap
  frame buffer
* paranoia: panic if a) the mmap frame buffer is already allocated when
  we try to allocate it, or b) the mmap frame buffer is not allocated when
  we try to add frames to it

tested by several

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars