This is because calls with M_WAIT (now M_TRYWAIT) may not wait
forever when nothing is available for allocation, and may end up
returning NULL. Hopefully we now communicate more of the right thing
to developers and make it very clear that it's necessary to check whether
calls with M_(TRY)WAIT also resulted in a failed allocation.
M_TRYWAIT basically means "try harder, block if necessary, but don't
necessarily wait forever." The time spent blocking is tunable with
the kern.ipc.mbuf_wait sysctl.
M_WAIT is now deprecated but still defined for the next little while.
* Fix a typo in a comment in mbuf.h
* Fix some code that was actually passing the mbuf subsystem's M_WAIT to
malloc(). Made it pass M_WAITOK instead. If we were ever to redefine the
value of the M_WAIT flag, this could have became a big problem.
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.
Now most big problem of IPv6 is getting IPv6 address
assignment.
6to4 solve the problem. 6to4 addr is defined like below,
2002: 4byte v4 addr : 2byte SLA ID : 8byte interface ID
The most important point of the address format is that an IPv4 addr
is embeded in it. So any user who has IPv4 addr can get IPv6 address
block with 2byte subnet space. Also, the IPv4 addr is used for
semi-automatic IPv6 over IPv4 tunneling.
With 6to4, getting IPv6 addr become dramatically easy.
The attached patch enable 6to4 extension, and confirmed to work,
between "Richard Seaman, Jr." <dick@tar.com> and me.
Approved by: jkh
Reviewed by: itojun
packet divert at kernel for IPv6/IPv4 translater daemon
This includes queue related patch submitted by jburkhol@home.com.
Submitted by: queue related patch from jburkhol@home.com
Reviewed by: freebsd-arch, cvs-committers
Obtained from: KAME project
