sk: jumbo buffer

[Gergo Szakal]

Sepherosa Ziehau wrote:
We can handle it this way:
1) jumbo ring is still created during attaching, but in addition we
create a bunch of dmamap for RX mcluster on attach patch too
2) in ifnet.if_init()'s RX buffer initialization, if ifnet.if_mtu >
(ETHERMTU + ETHER_HDR_LEN + ETHER_CRC_LEN) then we use jumbo ring,
else we use mcluster.
I will give you a patch to try either today or tomorrow.
Many-many thanks in advance. I have experienced it on another bridge, 
both interfaces are at 100FD there.