VirtIO is a platform for IO virtualization, common to several hypervisors (and QEMU).
The guest operating system needs specialized drivers to handle these devices.
Supported devices list
edit| Function | Bus | Type | Device | Usage example |
|---|---|---|---|---|
| Networking | PCI | 10Gb/s | virtio-net-pci | -net nic,model=virtio ...
|
| Storage | PCI | SCSI | virtio-scsi-pci | -device virtio-scsi-pci -drive file=disk.img,if=none,id=hd0 -device scsi-hd,drive=hd0 ...
|
| Storage | PCI | Custom | virtio-blk | -drive file=disk.img,if=virtio ...
|
| Memory | PCI | RAM | virtio-balloon-pci | |
| Serial | PCI | Serial | virtio-serial-pci | |
| Random Number Generator | PCI | RNG | virtio-rng-pci | → virtio-rng-pci |
virtio-rng-pci
editEntropy sources
editTo set up a VirtIO RNG, you first need to provide a source of entropy for it.
For devices exported by the kernel on UNIX-like systems, you can do so like this:
-object rng-random,filename=/dev/random,id=rng0
It is obviously not limited to the kernel RNG, you can choose a hardware RNG too in the very same way.
It also supports EGD, though it is not recommended because of its poor performance.
Example: -chardev socket,host=10.199.13.151,port=9000,id=chr0 -object rng-egd,chardev=chr0,id=rng0
Adding the actual device
editThen you can add the actual device, like this:
-device virtio-rng-pci,rng=rng0
There's also an option to limit the amount of data the guest received, to avoid starving the host.
Example: max-bytes=512,period=1000 for 512 bytes/s.
Supported Guest Systems
edit| OS | Drivers |
|---|---|
| Microsoft Windows | http://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers |
| Linux-based | 2.6.x, 3.x, 4.x |
| FreeBSD | 9.x (available), 10.x (in GENERIC kernel) https://www.freebsd.org/cgi/man.cgi?query=virtio&sektion=4 |
| NetBSD | 6.0+ |
| OpenBSD | 5.9+ |