1. A method of transmitting data generated in a virtual machine instantiated on a computer system to a network coupled to the computer system, the method comprising: accessing a virtual address pointer queue to retrieve a virtual address pointing to data to be transmitted, the virtual address pointer queue being in a shared memory region accessible to both the virtual machine and a virtualization system software layer that supports execution of the virtual machine, the shared memory region further comprising a data transmit buffer, the virtual address pointer queue having an ownership indicator; converting the virtual address into a physical address, wherein the physical address points to said data; and informing a network adapter device of the computer system of an availability of data pointed to by the physical address for transmission onto the network, the informing comprising adding a physical address to an entry of a physical transmit pointer queue accessible by a network adapter device and initiating an exception to be handled by the network adapter device.