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.\" Copyright 2020 Oxide Computer Company
.\"
.Dd October 3, 2020
.Dt VIOBLK 7D
.Os
.Sh NAME
.Nm vioblk
.Nd virtio block device
.Sh SYNOPSIS
.Pa /dev/dsk/cXt0d0
.Pa /dev/rdsk/cXt0d0
.Sh DESCRIPTION
The
.Nm
driver is a
.Xr blkdev 7D
based device that supports the virtio para-virtualization block device
specification which is commonly used by many hypervisors and emulators.
The device supports what the specification calls the more commonly found
.Sq legacy
interface for devices.
.Pp
The driver supports the following features, if offered by the device:
.Bl -dash
.It
Volatile write-cache
.It
Discarding unused sectors
.Pq ala TRIM, UNMAP
.It
Read-only device support
.It
Physical block sizes that are distinct from logical 512-byte blocks
.It
Synthesized disk geometry
.El
.Sh APPLICATION PROGRAMMING INTERFACE
For each device instance, a
.Xr blkdev 7D
instance is created and treated as an independent controller with a
single device, meaning that the
.Em cX
part of
.Em cXt0d0
will vary for each device.
Because the driver leverages the
.Xr blkdev 7D
framework, most standard disk manipulation utilities will function such
as
.Xr diskinfo 1M
for discovering devices,
.Xr format 1M
for manipulating partition tables,
.Xr iostat 1M
for seeing device I/O statistics, and a subset of the
.Xr dkio 7IO
ioctl requests to retrieve information about the device.
.Sh ARCHITECTURE
The
.Nm
driver is only supported on
.Sy x86 .
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/dsk/cXt0d0
Block device minor node.
.It Pa /dev/rdsk/cXt0d0
Character device minor node.
.It Pa /kernel/drv/amd64/vioblk
x86 device driver.
.El
.Sh SEE ALSO
.Xr diskinfo 1M ,
.Xr blkdev 7D ,
.Xr virtio 7D ,
.Xr dkio 7I
.Rs
.%T Virtual I/O Device (VIRTIO) Version 1.1
.%D April, 2019
.%U https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
.Re