RTEMS 4.5.1-pre3 On-Line Library

Non-Volatile Memory Driver Major and Minor Numbers

BSP and Device Driver Development Guide

12.1: Major and Minor Numbers

The major number of a device driver is its index in the RTEMS Device Address Table.

A minor number is associated with each device instance managed by a particular device driver. An RTEMS minor number is an unsigned32 entity. Convention calls dividing the bits in the minor number down into categories that specify an area of non-volatile memory and a partition with that area. This results in categories like the following:

area - indicates a block of non-volatile memory
partition - indicates a particular address range with an area

From the above, it should be clear that a single device driver can support multiple types of non-volatile memory in a single system. The minor number is used to distinguish the types of memory and blocks of memory used for different purposes.

BSP and Device Driver Development Guide