udevadm 트리거에 /sys rw가 필요한 이유는 무엇입니까?

systemd-udev-trigger 유닛 파일을 보면 systemd-udev-trigger 서비스를 시작하려면 /sys rw가 필요하다는 것을 알 수 있습니다. /usr/bin/udevadm Trigger --type=subsystems 명령을 확인했습니다. --action =Add; /usr/bin/udevadm 트리거 --type=devices --action=add에는 /sys rw도 필요합니다.

#systemctl cat  systemd-udev-trigger
# /usr/lib/systemd/system/systemd-udev-trigger.service
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=udev Coldplug all Devices
Documentation=man:udev(7) man:systemd-udevd.service(8)
DefaultDependencies=no
Wants=systemd-udevd.service
After=systemd-udevd-kernel.socket systemd-udevd-control.socket systemd-hwdb-update.service
Before=sysinit.target
ConditionPathIsReadWrite=/sys

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/bin/udevadm trigger --type=subsystems --action=add ; /usr/bin/udevadm trigger --type=devices --action=add