The bug happens only when the net is *sloooow* to send the
first packet (seems to happen w/ the arp requests being
sent). I can reproduce the bug quite easily by starting
a fs kernel and attaching to it from a different building
in our campus (yes, our network is slow :-( ).

I think that what happens is that a message buffer gets
linked twice in the transmit ring, perhaps due to a timeout
and retransmission.

Nevertheless, I had to get a fs up quickly and stopped
debugging by now to install one (within the same building,
hence working ;-) ).

My current problem is that although the box has two 4G IDE
disks, the fs kernel thinks the file system is full even
before unpacking the plan9.9gz package.

In case somebody has a hint about what I am doing wrong,
my config string for the device was ch0fh2.

Perhaps I'm just too sleepy...