before adding/removing packets from the queue. Also, the if_obytes and
if_omcasts fields should only be manipulated under protection of the mutex.
IF_ENQUEUE, IF_PREPEND, and IF_DEQUEUE perform all necessary locking on
the queue. An IF_LOCK macro is provided, as well as the old (mutex-less)
versions of the macros in the form _IF_ENQUEUE, _IF_QFULL, for code which
needs them, but their use is discouraged.
Two new macros are introduced: IF_DRAIN() to drain a queue, and IF_HANDOFF,
which takes care of locking/enqueue, and also statistics updating/start
if necessary.
driver seems relatively functional, but could use some souping up,
particularly in the performance area. This has both NetBSD and FreeBSD
attachment code and a fair amount of effort has been put into making
it easy to port to different *BSD platforms.
The basic design is a one tfd per mbuf transmit (with no transmit
related interrupts- tfds are gc'd as needed). The receive ring
uses a 2K buffer per rfd with a +2 byte adjust for the ethernet
header (so the payload is aligned). There's support that *almost*
works for doing large packets- the rfd chaining code works, but there's
some problem with getting good checksums at the IP reassembly level
(ditto for doing short tfd's too).
The chip has support for TCP checksums insertion for transmit and
TCP checksum calculation on receive (for both you have to do some
appropriate backoff && twiddling), but this isn't in place.
This is nearly entirely reverse engineered from the released Intel
driver, so there's a lot of "We have to do this but do not know why"
stuff. There is somebody who has the chip specs who works in FreeBSD
but they're being a bit standoffish about even sharing hints which
is somewhat annoying. It's also apparent that all I had to work with
were the first rev boards.
This driver has been lightly tested on intel && alpha, but only
point-to-point. There may be some issues with switches- use of
boot time environment variables that override EEPROM settings
(e.g., 'set wx_ilos=1' which inverts the sense of optical signal
loss) may help with this.
I had this out for review for three weeks, and nobody said anything
negative or positive, ergo, this checkin has no 'reviewed by' field
which I would have preferred.
