viomb —
VirtIO memory ballooning driver
viomb* at virtio?
The
viomb driver supports the
virtio-compliant memory ballooning device.
Memory ballooning works as follows:
- The host operator requests a guest to return some amount of memory to the
host (via, for example, the QEMU monitor balloon command).
- The hypervisor sends the request via the VirtIO memory ballooning
device.
- The guest
viomb driver requests
allocation of that amount of physical memory from the
OpenBSD memory management system.
- The
viomb device tells the hypervisor
the guest physical memory address of the allocated memory via the VirtIO
memory ballooning device.
intro(4),
virtio(4)
Rusty Russell, IBM
Corporation, Virtio PCI Card Specification,
http://ozlabs.org/~rusty/virtio-spec/.
The
viomb device driver first appeared in
OpenBSD 5.3.
![[OpenBSD]](/openbsd.gif){kind=small}