
The source and object for our overlayed kernel live here.
The kernel is not overlayed in the sense that overlays
are loaded and unloaded; instead, all overlays are always
resident and overlays are selected by changing segmentation
registers.  The overlayed kernel changes caused almost no
changes in the C source, the exceptions being the definition
of 'label_t' in param.h and types.h and the offsets defined
in reg.h.  However, several other changes have been made,
mostly to eliminate code that is not needed on 11/40 style
machines, see the defines in param.h.

