25.2.1 Exit Boot Services Event

UEFI Drivers for network interface controllers that perform DMA operations to a buffer in system memory in response to a received packet must create an Exit Boot Services Event in the Driver Binding Protocol Start() function. The notification function associated with this Exit Boot Services Event must update the network interface controller hardware to disable all further DMA activity. This guarantees that after ExitBootServices() is called, that the receive resources allocated to network driver are freed for OS usage.
Caution: If the network interface controller performs DMA due to received packets into system memory after ExitBootServices() is called, the DMA operations may corrupt memory that is now owned by the operating system.