Device Files in Linux PCI Device Drivers : Practice MCQ Questions & Answers with Explanations

In Linux, a device driver does not require a specific device file name to function — the name of a device file in /dev is purely for user-space convenience and has no bearing on driver operation. The kernel dispatches requests based on the device number (major + minor), not the file name. However, both a major number (to register the driver) and a minor number (to identify the device) are essential for driver operation.

In Linux, the connection between a device file and its device driver is established through the device number (comprising the major and minor numbers), not the name. The major number tells the kernel which driver to invoke, while the minor number identifies the specific device. The device file name in /dev is only for human-readable identification; the kernel uses the inode's device number to make the actual driver dispatch.

When a single driver manages multiple device files, all device files share the same major number (since they all map to the same driver), but each device file has a unique minor number. The driver uses the minor number internally to distinguish between different devices or sub-functionalities it controls.

In Linux, each physical or logical device instance that a driver manages must have its own corresponding device file in /dev. If a single driver handles N devices, you must create N device files — each with the same major number (pointing to the same driver) but different minor numbers (to distinguish individual devices).