0xd4559890: kernel MCHK trap by bsr4+0x4: srr1=0x49030Hmm. We may be reading/writing registers while the hardware has no power. I think that would cause a PCI exception that would lead to MCHK. Is the interface up when you do that? It should not fail, regardless, but I wonder if there is any difference between the problem case and the following? ifconfig ath0 up ifconfig ath0 mediaopt monitor
That's EXACTLY it. ath0 up makes it not panic. That's not to say it works, though, since ifconfig ath0 list scan shows nothing (and I know there are at least 20 networks visible from where I sit). I'll play with it more.
Thanks, John