proc.c:
	as a consequence of the implementation of proc_kill,
	any loop calling sleep should check for p->killed
	and be able to break out with an error return.
	it is better if you check *before* sleep.

syscall.c:
	cannot convince runoff1 to split the extern lists 
	  to fill previous page completely.

formatting:
	file.c filewrite leaks onto next page
	need to fix PAGEBREAK mechanism