Virtual Device Drivers
Virtual device drivers represent a particular variant of device drivers. They are used to emulate a hardware device, particularly in virtualization environments, for example when a DOS program is run on a Microsoft Windows computer or when a guest operating system is run on, for example, a Xen host. Instead of enabling the guest operating system to dialog with hardware, virtual device drivers take the opposite role and emulate a piece of hardware, so that the guest operating system and its drivers running inside a virtual machine can have the illusion of accessing real hardware. Attempts by the guest operating system to access the hardware are routed to the virtual device driver in the host operating system as e.g. function calls. The virtual device driver can also send simulated processor-level events like interrupts into the virtual machine.
Virtual devices may also operate in a non-virtualized environment. For example a virtual network adapter is used with a virtual private network, while a virtual disk device is used with iSCSI. The best example for virtual device drivers can be "Daemon Tools".
There are several variants of virtual device drivers.
Read more about this topic: Device Driver
Famous quotes containing the words virtual and/or device:
“Tragedy dramatizes human life as potentiality and fulfillment. Its virtual future, or Destiny, is therefore quite different from that created in comedy. Comic Destiny is Fortune—what the world will bring, and the man will take or miss, encounter or escape; tragic Destiny is what the man brings, and the world will demand of him. That is his Fate.”
—Susanne K. Langer (1895–1985)
“Johnson did not answer ...; but talking for victory and determined to be master of the field, he had recourse to the device which Goldsmith imputed to him in the witty words of one of Cibber’s comedies. “There is no arguing with Johnson; for when his pistol misses fire, he knocks you down with the butt end of it.””
—Samuel Johnson (1709–1784)