6.9 About the Sysfs File System

The sysfs virtual file system presents a user-spec view of the devices in the system, which changes dynamically whenever a device is inserted or removed. The directory hierarchy under /sys represents the global, bus, and device discovery layers. The files in the global layer report the power state of the device, which can also be set. The files in the bus layer report information such as the IRQ number and resources for each device. A device driver can also expose data or tunable interfaces via files in the file system.