1ec8f24b7SThomas Gleixner# SPDX-License-Identifier: GPL-2.0-only 25f3a211aSAlexey Dobriyanconfig SYSFS 36a108a14SDavid Rientjes bool "sysfs file system support" if EXPERT 45f3a211aSAlexey Dobriyan default y 5ba341d55STejun Heo select KERNFS 65f3a211aSAlexey Dobriyan help 75f3a211aSAlexey Dobriyan The sysfs filesystem is a virtual filesystem that the kernel uses to 85f3a211aSAlexey Dobriyan export internal kernel objects, their attributes, and their 95f3a211aSAlexey Dobriyan relationships to one another. 105f3a211aSAlexey Dobriyan 115f3a211aSAlexey Dobriyan Users can use sysfs to ascertain useful information about the running 125f3a211aSAlexey Dobriyan kernel, such as the devices the kernel has discovered on each bus and 135f3a211aSAlexey Dobriyan which driver each is bound to. sysfs can also be used to tune devices 145f3a211aSAlexey Dobriyan and other kernel subsystems. 155f3a211aSAlexey Dobriyan 165f3a211aSAlexey Dobriyan Some system agents rely on the information in sysfs to operate. 175f3a211aSAlexey Dobriyan /sbin/hotplug uses device and object attributes in sysfs to assist in 185f3a211aSAlexey Dobriyan delegating policy decisions, like persistently naming devices. 195f3a211aSAlexey Dobriyan 205f3a211aSAlexey Dobriyan sysfs is currently used by the block subsystem to mount the root 215f3a211aSAlexey Dobriyan partition. If sysfs is disabled you must specify the boot device on 225f3a211aSAlexey Dobriyan the kernel boot command line via its major and minor numbers. For 235f3a211aSAlexey Dobriyan example, "root=03:01" for /dev/hda1. 245f3a211aSAlexey Dobriyan 255f3a211aSAlexey Dobriyan Designers of embedded systems may wish to say N here to conserve space. 26