FireWire and Thunderbolt DMA is disabled if you set an firmware password. On systems which support Intel's VT-d technology, the OS will actually allow restricte

FireWire and Thunderbolt DMA is disabled if you set an firmware password. On systems which support Intel's VT-d technology, the OS will actually allow restricted DMA even with the firmware password set so you get almost all the benefits of DMA without the security compromise of having all memory exposed to the foreign device.