Sysfs

sysfs is a provided by the Linux kernel that exports information about various kernel subsystems, hardware devices, and associated device drivers from the kernel's device model to user space through s. In addition to providing information about various devices and kernel subsystems, exported virtual files are also used for their configuration. sysfs provides functionality similar to the sysctl mechanism found in BSD operating systems, with the difference that sysfs is implemented as a virtual file system instead of being a purpose-built kernel mechanism, and that, in Linux, sysctl configuration parameters are made available at /proc/sys/ as part of procfs, not sysfs which is mounted at /sys/. During the 2.5 development cycle, the Linux driver model was introduced to fix the following shortcomings of version 2.4: No unified method of representing driver-device relationships existed. There was no generic hotplug mechanism. procfs was cluttered with non-process information. Sysfs was designed to export the information present in the device tree which would then no longer clutter up procfs. It was written by Patrick Mochel. Maneesh Soni later wrote the sysfs backing store patch to reduce memory usage on large systems. During the next year of 2.5 development the infrastructural capabilities of the driver model and driverfs began to prove useful to other subsystems. kobjects were developed to provide a central object management mechanism and driverfs was renamed to sysfs to represent its subsystem agnosticism. Sysfs is mounted under the mount point. If it is not mounted automatically during initialization, it can be mounted manually using the mount command: mount -t sysfs sysfs /sys. ACPI Exports information about ACPI devices. PCI Exports information about PCI and PCI Express devices. PCI Express Exports information about PCI Express devices. USB Exports information about USB devices. SCSI Exports information about mass storage devices, including USB, SATA and NVMe interfaces.