2011/12/9 Daniel Wagner <wagi(a)monom.org&gt;: When we start ofonod nothing in udevadm monitor #ofonod -n & udevadm monitor [3] 26496 monitor will print the received events for: UDEV - the event which udev sends out after rule processing KERNEL - the kernel uevent ofonod[26496]: oFono version 1.0 because our device is on fixed port which is not USB or anything. root@crux:/mnt/ofono/ofono/src# systemctl list-units|grep ttyS sys-devi...y-ttyS0.device loaded active     plugged /sys/devices/platform/crux_serial/tty/ttyS0 sys-devi...y-ttyS1.device loaded active     plugged /sys/devices/platform/crux_serial/tty/ttyS1 sys-devi...y-ttyS2.device loaded active     plugged /sys/devices/platform/crux_serial/tty/ttyS2 sys-devi...y-ttyS3.device loaded active     plugged /sys/devices/platform/crux_serial/tty/ttyS3 sys-devi...ttySAC0.device loaded active     plugged /sys/devices/platform/s3c2440-uart.0/tty/ttySAC0 sys-devi...ttySAC1.device loaded active     plugged /sys/devices/platform/s3c2440-uart.1/tty/ttySAC1 sys-devi...ttySAC2.device loaded active     plugged /sys/devices/platform/s3c2440-uart.2/tty/ttySAC2 sys-devi...ttySAC3.device loaded active     plugged /sys/devices/platform/s3c2440-uart.3/tty/ttySAC3 root@crux:~# udevadm info --query=all  --path /sys/class/tty/ttySAC0 P: /devices/platform/s3c2440-uart.0/tty/ttySAC0 N: ttySAC0 E: DEVNAME=/dev/ttySAC0 E: DEVPATH=/devices/platform/s3c2440-uart.0/tty/ttySAC0 E: MAJOR=204 E: MINOR=64 E: SUBSYSTEM=tty E: TAGS=:systemd: E: UDEV_LOG=3 E: USEC_INITIALIZED=10265578