Linux Device Subsystem — Device Model, sysfs & Drivers

The Linux Device Model

This page visualizes the Linux device subsystem — the unified device model that the kernel uses to represent every piece of hardware. At its core are kobjects and ksets, organized into buses (PCI, USB, platform), device classes and drivers. The model is exported to userspace through sysfs (/sys), and udev listens for hotplug uevents to create device nodes and apply rules. The visualization is driven by real device telemetry.

Device Subsystem Concepts

• Device model — kobject/kset reference-counted objects that form the /sys hierarchy of devices, buses and classes.
• Buses — PCI, USB, platform and virtual buses that enumerate devices and match them to drivers.
• Driver binding — the probe/remove lifecycle that attaches a driver to a matching device.
• sysfs — the in-memory filesystem at /sys that exposes device attributes and topology to userspace.
• udev + hotplug — uevents from the kernel drive device-node creation, permissions and naming.
• Device classes — block, character and network devices, plus input, sound and GPU classes.

Kernel Architecture Context

The device subsystem is the bridge between the Linux kernel and physical hardware, sitting beneath the filesystem and network subsystems that ultimately depend on block and network devices. Understanding the device model — kobjects, buses, sysfs and driver binding — is a key part of the overall Linux architecture and kernel architecture: how hardware is discovered, named and made available to the rest of the system.