.\"-
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2024 The FreeBSD Foundation
.\"
.\" Portions of this software were developed by Christos Margiolis
.\" <christos@FreeBSD.org> under sponsorship from the FreeBSD Foundation.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\"
.Dd July 15, 2024
.Dt SND_DUMMY 4
.Os
.Sh NAME
.Nm snd_dummy
.Nd Dummy audio driver
.Sh SYNOPSIS
To load the driver at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
snd_dummy_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver implements a virtual testing device, meaning it does not correspond to a
physical sound card.
It is intended for testing, so that test programs do not need to rely on
hardware being present in the machine in order to run.
.Pp
The driver attaches as a regular PCM device, with two channels (one playback
and one recording), as well as a mixer.
.Pp
Playback works by discarding all input, and recording by returning silence
(zeros).
.Sh SEE ALSO
.Xr sound 4 ,
.Xr loader.conf 5 ,
.Xr loader 8
.Sh AUTHORS
The
.Nm
driver was implemented by
.An Christos Margiolis Aq Mt christos@FreeBSD.org
under sponsorship from the
.Fx
Foundation.
.Sh CAVEATS
Because the driver automatically attaches once the module is loaded, it can
only be attached once.