polling(4) rocks!

[Mark Magiera]

> Why can some NIC use polling and others not ?
>
> eg I went to turn on polling on my BCM5782 Broadcom NetXtreme Gigabit
>    Ethernet Card. And bge(4) doesn't mention anything about polling.
>
> Is it a hardware feature of the NIC ?
>
>  - aW
>

>From `man 4 polling`:
SUPPORTED DEVICES
     Polling requires explicit modifications to the device drivers.  As of
     this writing, the dc(4), em(4), fxp(4), rl(4), and sis(4) devices are
     supported, with other in the works.

This seems to suggest all hardware supports it, just some drivers don't at
this/that(2002) moment in time.

-- Mark Magiera