setting the 'max packet size' register in window 3. This only
works for cards based on the cyclone or newer chipsets (i.e. it
won't work with the original 3c905/boomerang cards).
There is a trick which will work with the boomerang, which is to turn
on the 'large packets ok' bit in the MAC control register, however this
lets the chip accept any frame up to 4K in length, which is larger than
the mbuf cluster buffers we use to receive frames. If somebody sends us
such a frame and the chip DMAs it to us, it could write past the end
of the cluster buffer and clobber something.
PR: kern/27742
7d1b125b93