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10.1 Special Files

10.1.2 Major and minor devices

The major number identifies the kernel driver that communicates with the device. The minor number identifies the location of the device, i.e. it divides a physical device into logical devices.

The major number directs you to the proper controller and mode. Minor device numbers 0 --> 7 refer to portions of drive 0; minor devices 8-->15 refer to drive 1, etc.

For SunOS 5.X the system is responsible for assigning unused major numbers when you add a device, so these should not be hard-coded in the drivers. Minor numbers are assigned by the driver.

Unix System Administration - 8 AUG 1996
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