Inside Solaris™ 9

Major and Minor Device Numbers

Each device has a major and minor device number assigned. These numbers identify the proper device location and device driver to the kernel. This number is used by the operating system to key into the proper device driver whenever a physical device file corresponding to one of the devices it manages is opened. The major device number indicates the general device class, such as disk, tape, or serial line. The minor device number indicates the specific member within that class. All devices managed by a given device driver contain a unique minor number. Some drivers of pseudo devices (software entities set up to look like devices) create new minor devices on demand. Together, the major and minor numbers uniquely ...