220 lines
6.7 KiB
Groff
220 lines
6.7 KiB
Groff
.\"
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.\" Copyright (c) 1998, Luigi Rizzo
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 3, 1998
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.Dt PCM 4
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.Os FreeBSD
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.Sh NAME
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.Nm pcm ,
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.Nm snd
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.Nd FreeBSD PCM audio device driver
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.Sh SYNOPSIS
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For a card with bridge driver support, and a PnP card:
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.Cd "device pcm"
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.Pp
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For a card without bridge driver support, and a non-PnP card:
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.Cd "device pcm0 at isa? port? irq 5 drq 1 flags 0x15"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for PCM audio play and capture.
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This driver
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also supports various PCI and WSS/MSS compatible ISA sound cards, and
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AC97 mixer.
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True full duplex operation is available on most cards.
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.Pp
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If your sound card is supported by a bridge driver,
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.Nm
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driver works
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in conjunction with the bridge driver.
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.Pp
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Apart from the usual parameters, the flags field is used to specify
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the secondary DMA channel (generally used for capture in full duplex
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cards). Flags are set to 0 for cards not using a secondary DMA
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channel, or to 0x10 + C to specify channel C.
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.Pp
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The driver works best with WSS/MSS cards, which have a very clean
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architecture and an orthogonal set of features.
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They also happen to be
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among the cheapest audio cards on the market.
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.Pp
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The driver does its best to recognize the installed harware and drive
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it correctly, so that you don't have to give too many details in the
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kernel config files.
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For PCI and ISA PnP cards this is actually easy
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since they identify themselves.
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For legacy ISA cards, the driver looks
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for MSS cards at addresses 0x530 and 0x604 (obviously, unless overridden
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in the kernel config file by specifying an address).
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.Sh IOCTL
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The driver supports most of the Voxware ioctls(), and most
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applications work unmodified (including popular mpeg players and linux
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binaries). A few
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differences exist (the most important one is the ability to use
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memory-mapped access to the audio buffers). As a consequence, some
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applications may need to be recompiled with a slightly modified
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audio module. See /usr/include/sys/soundcard.h for a complete
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list of the supported ioctls.
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.Sh SUPPORTED CARDS
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.Pp
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Below we include a list of supported codecs/cards.
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If your sound card
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is not listed here, it may be supported by a bridge driver.
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.Bl -tag -width 2m % begin list
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.It CS4237, CS4236, CS4232, CS4231 (ISA)
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.Pp
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All these cards work perfectly in full duplex using the MSS mode.
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This chipset is used, among others, on the A/Open AW35 and AW32, on
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some Intel motherboards, and (the CS4231) on some non-PnP cards.
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.Pp
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The CS4232 is reported as buggy in the Voxware documentation but
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I am not sure if this is true.
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On one of my Intel motherboards,
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capture does not work simply because the capture DMA channel is
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not wired to the ISA DMA controller.
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.It Yamaha OPL-SAx (ISA)
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.Pp
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Works perfectly in all modes.
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This chip is used in several PnP cards,
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but also (in non-PnP mode) on motherboards and laptops (e.g. the
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Toshiba Libretto).
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.It OPTi931 (ISA)
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.Pp
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The chip is buggy, but the driver has many workarounds to make it work
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in full duplex because for some time these were the only full duplex
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cards I could find. u-law formats uses U8 format internally because of
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a bug in the chip.
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.It Trident 4DWave DX/NX (PCI)
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.Pp
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.It ENSONIQ AudioPCI ES1370/1371 (PCI)
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.Pp
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Creative Labs SoundBlaster PCI is supported as well.
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.It ESS Solo-1/1E (PCI)
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.Pp
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This chip has some unresolved problems with high bandwidth (44 kHz 16
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bit stereo) recording. These problems may result in
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.Pa hwptr went backwards
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warnings.
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.It NeoMagic 256AV/ZX (PCI)
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.Pp
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.El
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.Sh FILES
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The following commonly used symbolic links to real device nodes
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should be present:
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.Pp
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.Bl -tag -width /dev/sequencer -compact
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.It Pa /dev/audio
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Sparc-compatible audio device
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.It Pa /dev/dsp
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Digitized voice device
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.It Pa /dev/dspW
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Like
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.Pa /dev/dsp ,
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but 16 bits per sample
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.It Pa /dev/midi
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Raw midi access device
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.It Pa /dev/mixer
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Control port mixer device
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.It Pa /dev/music
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Level 2 sequencer interface
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.It Pa /dev/sequencer
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Sequencer device
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.It Pa /dev/pss
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Programmable device interface
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.El
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.Pp
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Each symbolic link refers to a device node of the same name,
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but with a unit number appended.
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The unit number for each device matches the unit number of the
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device probed at boot time.
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Device probe messages can be examined with the
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.Xr dmesg 8
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utility.
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.Pp
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All the appropriate device nodes and symbolic links
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for the
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.Ql pcm0
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device would created with the following commands:
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.Bd -literal -offset indent
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cd /dev; sh MAKEDEV snd0
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.Ed
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.Pp
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Similarly, the device nodes and symbolic links for the
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.Ql pcm1
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device would be created as follows:
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.Bd -literal -offset indent
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cd /dev; sh MAKEDEV snd1
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.Ed
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.Pp
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Since the
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.Pa /dev/MAKEDEV
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utility creates symbolic links that will be used by
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many utilities by default,
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the device nodes and symbolic links for the
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preferred audio device in systems with multiple audio devices
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should be created last.
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.Sh DIAGNOSTICS AND TROUBLESHOOTING
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.Bl -tag -width 2m
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.It ac97: dac not ready
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AC97 codec is not likely to be accompanied with the sound card.
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.It unsupported subdevice XX
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A device node is not created properly.
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.El
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.Sh BUGS
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Some features of your cards (e.g. global volume control) might not
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be supported on all devices.
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.Sh HISTORY
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The
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.Nm
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device driver first appeared in
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.Fx 2.2.6 ,
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rewritten in
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.Fx 4.0 .
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.Sh SEE ALSO
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.Xr sbc 4
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.Xr gusc 4
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.Xr csa 4
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.Sh AUTHORS
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.An Luigi Rizzo Aq luigi@iet.unipi.it
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initially wrote the
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.Nm
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device driver and this manual page.
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.An Cameron Grant Aq gandalf@vilnya.demon.co.uk
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totally revised the device driver.
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.An Seigo Tanimura Aq tanimura@r.dl.itc.u-tokyo.ac.jp
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revised this manual page.
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