.\" Copyright (c) 2012 Bryan Venteicher
.\" All rights reserved.
.\"
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.Dd June 24, 2012
.Dt VIRTIO_SCSI 4
.Os
.Sh NAME
.Nm virtio_scsi
.Nd VirtIO SCSI driver
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device virtio_scsi"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
virtio_scsi_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
device driver provides support for VirtIO SCSI devices.
.Sh LOADER TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Xr loader.conf 5 .
.Bl -tag -width "xxxxxx"
.It Va 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.
.El
.Sh DEBUGGING
To enable debugging prints from the
.Nm
driver, set the
.Bd -literal -offset indent
hw.vtscsi.X.debug_level
.Ed
.Pp
variable, where X is the adapter number, either in
.Xr loader.conf 5
or via
.Xr sysctl 8 .
The following bits have the described effects:
.Bl -tag -width 6n -offset indent
.It 0x01
Enable informational prints.
.It 0x02
Enable prints for driver errors.
.It 0x04
Enable tracing prints.
.El
.Sh SEE ALSO
.Xr virtio 4
.Sh HISTORY
The
.Nm
driver was written by
.An Bryan Venteicher Aq Mt bryanv@FreeBSD.org .
It first appeared in
.Fx 10.0 .