systemd-udev-settle.service - Man Page

systemd-udev-settle​.service

This service calls udevadm settle to wait until all events that have been queued by udev(7) have been processed​. It is a crude way to wait until "all" hardware has been discovered​. Services may pull in this service and order themselves after it to wait for the udev queue to be empty​.

Using this service is not recommended​. There can be no guarantee that hardware is fully discovered at any specific time, because the kernel does hardware detection asynchronously, and certain buses and devices take a very long time to become ready, and also additional hardware may be plugged in at any time​. Instead, services should subscribe to udev events and react to any new hardware as it is discovered​. Services that, based on configuration, expect certain devices to appear, may warn or report failure after a timeout​. This timeout should be tailored to the hardware type​. Waiting for systemd-udev-settle​.service usually slows boot significantly, because it means waiting for all unrelated events too​.

udev(7), udevadm(8)

systemd.directives(7), systemd.index(7), udevadm(8).