LinkDevice trait gains is_enabled() and set_enabled() with defaults.
EthernetLink stores enabled flag (default: true). When disabled,
link_state() reports 'down' regardless of hardware_address presence.
netcfg/ifaces/eth0/enabled is rw:
cat /scheme/netcfg/ifaces/eth0/enabled → 'up' or 'down'
echo up > .../enabled → bring interface up
echo down > .../enabled → bring interface down
echo on/off/1/0/yes/no → also accepted
Mirrors Linux 'ip link set dev <state>'.
Pre-existing link state (hardware_address Some/None) unchanged;
the enabled flag adds a software override layer that can be
toggled without restarting the netstack.
Red Bear OS
9bab466704