File: //etc/udev/rules.d/05-udev-early.rules
# sysfs is populated after the event is sent
ACTION=="add", DEVPATH=="/devices/*", ENV{PHYSDEVBUS}=="?*", WAIT_FOR_SYSFS="bus"
ACTION=="add", SUBSYSTEM=="net", WAIT_FOR_SYSFS="address"
ACTION=="add", SUBSYSTEM=="scsi", WAIT_FOR_SYSFS="ioerr_cnt"
# ignore these events until someone needs them
SUBSYSTEM=="drivers", OPTIONS="ignore_device"
SUBSYSTEM=="module", OPTIONS="ignore_device"
ACTION=="add", SUBSYSTEM=="firmware", ENV{FIRMWARE}=="*", RUN="/sbin/firmware_helper", OPTIONS="last_rule"