=== DF-5053 baseline run (guest serial console; ssh dies at panic) ===
$ vm.sh run_root 'kldload /root/df5053/qsmedia.ko'
  (ssh times out -- guest panics during attach)
$ vm.sh status -> down
$ vm.sh log ->

qsmedia0: <synthetic single-PHY MII controller (DF-5053)> on motherboard
qsmedia: probing MII bus (QS6612 id1=0x0181 id2=0x4401, pre-reset BMSR=0x7808)
miibus0: <MII bus> on qsmedia0
qsphy0: <QS6612 10/100 media interface> on miibus0
qsphy0:  no media present
ifmedia_set: no match for 0x0/0xfffffff
panic: ifmedia_set
cpuid = 0
Trace beginning at frame 0xfffff80117cfb548
ifmedia_set() at ifmedia_set+0x53 0xffffffff807432b3 
ifmedia_set() at ifmedia_set+0x53 0xffffffff807432b3 
qsphy_attach() at qsphy_attach+0x159 0xffffffff80564879 
device_doattach() at device_doattach+0x3af 0xffffffff8068dbef 
bus_generic_attach() at bus_generic_attach+0x1a 0xffffffff8068f7ea 
miibus_attach() at miibus_attach+0x4b 0xffffffff80558bab 
Debugger("panic")