viomb(4) [netbsd man page]

VIOMB(4)						   BSD Kernel Interfaces Manual 						  VIOMB(4)

NAME

     viomb -- VirtIO memory ballooning driver

SYNOPSIS

     virtio* at pci? dev ? function ?
     viomb*  at virtio?

DESCRIPTION

     virtio(4) defines an interface for efficient, standard, and extensible I/O between the hypervisor and the virtual machine.  The viomb driver
     supports the virtio-compliant memory ballooning device.

     Memory ballooning works as follows:

     1.   The host operator requests a guest to return some amount of memory to the host (via e.g. Qemu monitor balloon command).
     2.   The hypervisor sends the request via VirtIO memory ballooning device.
     3.   The guest viomb driver requests allocation of that amount of physical memory from the NetBSD memory management system.
     4.   The 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.

SEE ALSO

     virtio(4), sysctl(8)

     Rusty Russell, IBM Corporation, Virtio PCI Card Specification, http://ozlabs.org/~rusty/virtio-spec/.

HISTORY

     The viomb device driver appeared in NetBSD 6.0.

BUGS

     The userland interface should be same as the Xen ballooning device.

BSD
								 November 26, 2011							       BSD

VIRTIO_BLK(4)						   BSD Kernel Interfaces Manual 					     VIRTIO_BLK(4)

NAME

     virtio_blk -- VirtIO Block driver

SYNOPSIS

     To compile this driver into the kernel, place the following lines in your kernel configuration file:

	   device virtio_blk

     Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

	   virtio_blk_load="YES"

DESCRIPTION

     The virtio_blk device driver provides support for VirtIO block devices.

LOADER TUNABLES

     Tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5).

     hw.vtblk.no_ident

     hw.vtblk.X.no_ident

	     These tunables disable retrieving the device identification string from the hypervisor either globally or per-device.  The default
	     value is 0.

     hw.vtblk.writecache_mode

     hw.vtblk.X.writecache_mode

	     These tunables determine the write cache mode globally or per-device.  The mode can changed only if the ConfigWCE feature is negoti-
	     ated.  Set to 0 for writethrough mode, 1 for writeback mode, and -1 to leave it as-is.  The default value is to leave as-is.

SYSCTL VARIABLES

     The following variables are available as sysctl(8) variables.

     dev.vtblk.X.writecache_mode

	     The write cache mode of the device can be either writethrough (0) or writeback (1).  If the ConfigWCE feature is negotiated, the
	     write cache mode can be toggled between writethrough and writeback.

SEE ALSO

     virtio(4)

HISTORY

     The virtio_blk driver was written by Bryan Venteicher <bryanv@FreeBSD.org>.  It first appeared in FreeBSD 9.0.

BSD
								   July 2, 2013 							       BSD