netpoll/kgdb-over-ethernet/netconsole

Ok, this is an update of my netpoll API work against -mm4. This new version fixes some issues with SMP and gets stuff working without driver hacks for NAPI devices (tested with tg3 on SMP - hurray for new devel box).

(BTW, the old approach to handling tg3 didn't quite work on SMP as it didn't take the hooked packets off the rx ring and they got handed to softnet before we made it into the debugger. Softnet would then send an icmp unreachable, taking down the gdb socket. It's actually really hard to fix this safelySo consider this a bug
fix too.)

The first patch replaces (aka breaks) the kgdb-over-ethernet hooks, so you'll need the second patch to make kgdb go again. The third patch, which adds netconsole, is optional but very handy.

Matt Mackall : http://www.selenic.com : of or relating to the moon