| VIOMB(4) | Device Drivers Manual | VIOMB(4) | 
viomb —
virtio* at pci? dev ? function ?
viomb* at virtio?
viomb driver supports the
  virtio-compliant memory ballooning device.
Memory ballooning works as follows:
viomb driver requests allocation of that
      amount of physical memory from the NetBSD memory
      management system.viomb device tells the hypervisor the guest
      physical memory address of the allocated memory via VirtIO memory
      ballooning device.The sysctl node hw.viomb.npages shows the
    requested number of memory pages to return to the hypervisor, while
    hw.viomb.actual shows the actual number of memory
    pages that are already returned to the hypervisor.
Rusty Russell, IBM Corporation, Virtio PCI Card Specification, http://ozlabs.org/~rusty/virtio-spec/.
viomb device driver appeared in
  NetBSD 6.0.
| August 25, 2020 | NetBSD 10.1 |