DF-5009 — fixed-kernel run (patch from fix.diff applied to the guest's
/usr/src copy; nativekernel + installkernel; DragonFly 6.5-DEVELOPMENT #1
Fri Sep 25 20:48:43 UTC 2026)

# 1. rebuild module (also proves the tree still builds with the fix)
root@dfbsd# cd /root/df5009 && make SYSDIR=/usr/src/sys
cc ... -c fakemic.c
cc -Wl,--build-id=sha1 -nostdlib ... -o fakemic.ko fakemic.o

# 2. load dual-PHY bus
root@dfbsd# kldload /root/df5009/fakemic.ko
LOADED
rlphy0: <RTL8201L 10/100 media interface> on miibus0
ukphy0: ... 100baseT4, auto

# 3. arm the IDENTICAL trigger
root@dfbsd# sysctl -w kern.fakemic_arm=1
kern.fakemic_arm: 0 -> 1
NO-PANIC-SURVIVED
root@dfbsd# uptime
 8:59PM  up 34 secs, 0 users, load averages: 0.16, 0.04, 0.02

dmesg tail:
fakemic: operator selects SIBLING PHY media ("ifconfig fakemic0 media 100baseT4")
fakemic: ifm_cur inst=1; invoking MII watchdog mii_tick()
fakemic: mii_tick survived -- rlphy KASSERT did NOT fire

=> same trigger, kernel stays up; rlphy_service() now returns 0 for a
   foreign instance instead of asserting.