virtio_scsi(4) [freebsd man page]

VIRTIO_SCSI(4)						   BSD Kernel Interfaces Manual 					    VIRTIO_SCSI(4)

NAME

     virtio_scsi -- VirtIO SCSI driver

SYNOPSIS

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

	   device virtio_scsi

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

	   virtio_scsi_load="YES"

DESCRIPTION

     The virtio_scsi device driver provides support for VirtIO SCSI devices.

LOADER TUNABLES

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

     hw.vtscsi.bus_reset_disable
	     In the initial QEMU release with VirtIO SCSI support, in-flight operations were not aborted when stopping the device, rendering bus
	     reset ineffective. This tunable disables attempts to issue reset bus commands. The default value is 1.

DEBUGGING

     To enable debugging prints from the virtio_scsi driver, set the

	   hw.vtscsi.X.debug_level

     variable, where X is the adapter number, either in loader.conf(5) or via sysctl(8).  The following bits have the described effects:

	   0x01    Enable informational prints.

	   0x02    Enable prints for driver errors.

	   0x04    Enable tracing prints.

SEE ALSO

     virtio(4)

HISTORY

     The virtio_scsi driver was written by Bryan Venteicher <bryanv@FreeBSD.org>.  It first appeared in FreeBSD 10.0.

BSD
								   June 24, 2012							       BSD

VIRTIO(4)						   BSD Kernel Interfaces Manual 						 VIRTIO(4)

NAME

     virtio -- VirtIO Device Support

SYNOPSIS

     To compile VirtIO device support into the kernel, place the following lines in your kernel configuration file:

	   device virtio
	   device virtio_pci

     Alternatively, to load VirtIO support as modules at boot time, place the following lines in loader.conf(5):

	   virtio_load="YES"
	   virtio_pci_load="YES"

DESCRIPTION

     VirtIO is a specification for para-virtualized I/O in a virtual machine (VM).  Traditionally, the hypervisor emulated real devices such as an
     Ethernet interface or disk controller to provide the VM with I/O.	This emulation is often inefficient.

     VirtIO defines an interface for efficient I/O between the hypervisor and VM.  The virtio module provides a shared memory transport called a
     virtqueue.  The virtio_pci device driver represents an emulated PCI device that the hypervisor makes available to the VM.	This device pro-
     vides the probing, configuration, and interrupt notifications needed to interact with the hypervisor.  FreeBSD supports the following VirtIO
     devices:

	   Ethernet  An emulated Ethernet device is provided by the vtnet(4) device driver.

	   Block     An emulated disk controller is provided by the virtio_blk(4) device driver.

	   SCSI      An emulated SCSI HBA is provided by the virtio_scsi(4) device driver.

	   Balloon   A pseudo-device to allow the VM to release memory back to the hypervisor is provided by the virtio_balloon(4) device driver.

SEE ALSO

     virtio_balloon(4), virtio_blk(4), virtio_console(4), virtio_scsi(4), vtnet(4)

HISTORY

     Support for VirtIO first appeared in FreeBSD 9.0.

AUTHORS

     FreeBSD support for VirtIO was first added by Bryan Venteicher <bryanv@FreeBSD.org>.

BSD
								 January 22, 2012							       BSD