Mastering Embedded Linux Programming - Second Edition

The reg property

The memory and cpu nodes have a reg property, which refers to a range of units in a register space. A reg property consists of two values representing the start address and the size (length) of the range. Both are written as zero or more 32-bit integers, called cells. Hence, the memory node refers to a single bank of memory that begins at 0x80000000 and is 0x20000000 bytes long.

Understanding reg properties becomes more complex when the address or size values cannot be represented in 32 bits. For example, on a device with 64-bit addressing, you need two cells for each:

/ {    #address-cells = <2>;    #size-cells = <2>;    memory@80000000 {        device_type = "memory";        reg = <0x00000000 0x80000000 0 0x80000000>;    };};

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