Device Management and Control Data

Hardened drivers must act with extreme caution when using pointers, array indexes or memory offsets which are read or calculated from data retrieved from the device. These values should not be used until they are checked to ensure that they are within an expected range and have legal alignment. These types of pointer mechanisms can become misleading or malignant if the device has developed a fault.

A hardened driver will never loop simply upon a register value. An infinite loop may occur if a device breaks and returns stuck data. The hardened driver must have a method to break this type of loop.

Driver state information should be maintained in main memory, not on an I/O card.