external storage. Highlights:
- additional "void *" argument to (*ext_free)(), an opaque
cookie for use by the free function.
- MCLALLOC() and MCLFREE() calls are gone. They are replaced
by MEXTADD() (add external storage to mbuf), MEXTMALLOC()
(malloc() external storage and attach to mbuf), and
MEXTREMOVE() (remove external storage from mbuf).
- completely new external storage reference counting
mechanism; mclrefcnt[] is gone.
These changes will eventually be used to pass driver DMA buffers up
the network stack, and reduce/eliminate copies in certain code paths
(e.g. NFS writes).
From Matt Thomas <matt@3am-software.com> and myself <thorpej@nas.nasa.gov>,
with some input from Chris Demetriou <cgd@cs.cmu.edu> and review by
Charles Hannum <mycroft@mit.edu>.
2a4b742e6a