QEMU provides virtual hardware devices to the guest system, allowing it to interact with the external world, just like if it were running on real hardware.
Devices can be added using the
-device parameter when starting, or with the
device_add command in QEMU monitor (if the operating system and bus support hotplug).
Some devices take modifiers, that may affect the device's behavior and interface.
qemu -device devicename,modifier1=value1,modifier2=value2 ...