The pipe will be pre-loaded with one single-character token for each
available job. To obtain an extra slot you must read a single
character from the jobserver pipe; to release a slot you must write a
-single character back into the jobserver pipe.
+single character back into the jobserver pipe. Note that the read
+side of the jobserver pipe is set to ``blocking'' mode.
To access the pipe you must parse the @code{MAKEFLAGS} variable and
look for the argument string @code{--jobserver-auth=R,W} where