Missing Driver Entry Points

Missing Driver Entry Points

If your driver is missing a definition for an entry point, lboot generates a stub that points to nulldev(). If the user makes the corresponding system call on that device, the system call returns an error. Your driver must always include definitions for some driver entry points, such as the device open() and close() entry points. However, many devices do not perform memory mapping and, therefore, do not need the map() and unmap() entry points. You may omit such entry points from the driver object module.