An application within a VDM cannot corrupt or destroy a virtual device driver, since the virtual device driver operates in protected mode outside the V86 mode address space, and is thus not accessible by the application. However, the parameters passed to a virtual device driver from the VDM must be carefully checked before being acted upon, in order to ensure that the service request is valid. Failure to do so may result in failure of a virtual device driver due to an invalid instruction or invalid data.
System registers must not be modified by a virtual device driver. Only certain flags may be modified. These are as follows:
Failure to observe these rules by a virtual device driver may result in failure of the VDM's parent process, and possible corruption of the virtual device driver itself.