On Di, 13.03.18 03:35, Ong, Hean Loong (hean.loong.ong at intel.com) wrote: > Hi, > > I have been faced with intermittent issues with regards to the > dev-ttyS0.device timing out upon boot up Is this on a current systemd and kernel? If not, please upgrade to something more current before trying to debug this. When this happens, acquire a debug shell (for example by adding systemd.debug_shell=1 to the kernel command line), and check if "udevadm info /dev/ttyS0" shows the device properly probed and with the "systemd" tag applied. Lennart -- Lennart Poettering, Red Hat