[fixed kernel]
[host] devfs mounted at /jail/dev
[host] /jail/dev/devfs present (control node visible in jail)
[host] /jail/dev/mem hidden by host rule (ruleset enforced)
[host] /dev/console mode pre-jail: 0600
[jail] uid=0 euid=0, jailed
[jail] opening /dev/devfs from inside jail...
[jail] /dev/devfs OPENED from jailed root        <- 0600 vnode gate only
jail_show: ioctl ADD show: Operation not permitted  <- FIX: jailed() gate
[host] jail child exit status: 256
[host] /dev/console mode post-jail: 0600          <- host untouched now