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Soundcore Notes on Modular Sound Drivers and Soundcore
Wade Hampton
11/20/1998
Purpose:
========
This document provides some general notes on the modular
sound drivers and their configuration, along with the
support modules sound.o, soundlow.o and soundcore.o.
Note, some of this probably should be added to the Sound-HOWTO!
Copying:
========
none
History:
========
0.1.0 11/20/1998 First version
Modular Sound Drivers:
======================
Thanks to the GREAT work by Alan Cox (alan@lxorguk.ukuu.org.uk),
[And Oleg Drokin, Thomas Sailer, Andrew Veliath and more than a few
others - not to mention Hannu's original code being designed well
enough to cope with that kind of chopping up](Alan)
the standard Linux kernels support a modular sound driver. From
Alan's comments in linux/drivers/sound/README.FIRST:
The modular sound driver patches were funded by Red Hat Software
(www.redhat.com). The sound driver here is thus a modified version of
Hannu's code. Please bear that in mind when considering the appropriate
forums for bug reporting.
The modular sound drivers may be loaded via insmod or modprobe.
To support all the various sound modules, there are three general
support modules that must be loaded first:
soundcore.o: Top level handler for the sound system, provides
a set of functions for registration of devices
by type.
soundlow.o: Low-level sound drivers which are not part of
OSS/Lite (Open Sound System), including SB32/AWE
synthesizer, etc.
sound.o: Common sound functions required by all modules.
For the specific sound modules (e.g., sb.o for the Soundblaster),
read the documentation on that module to determine what options
are available, for example IRQ, address, DMA.
Warning, the options for different cards sometime use different names
for the same or a similar feature (dma1= versus dma16=). As a last
resort, inspect the code (search for MODULE_PARM).
INSMOD:
=======
If loading via insmod, the common modules must be loaded in the
order below BEFORE loading the other sound modules. The card-specific
modules may then be loaded (most require parameters). For example,
I use the following via a shell script to load my SoundBlaster:
SB_BASE=0x240
SB_IRQ=9
SB_DMA=3
SB_DMA2=5
SB_MPU=0x300
#
echo Starting sound
/sbin/insmod soundcore
/sbin/insmod soundlow
/sbin/insmod sound
#
echo Starting sound blaster....
/sbin/insmod uart401
/sbin/insmod sb io=$SB_BASE irq=$SB_IRQ dma=$SB_DMA dma16=$SB_DMA2 mpu_io=$SB_MP
MODPROBE:
=========
If loading via modprobe, these common files are automatically loaded
when requested by modprobe. For example, my /etc/conf.modules contains:
alias sound sb
options sb io=0x240 irq=9 dma=3 dma16=5 mpu_io=0x300
All you need to do to load the module is:
/sbin/modprobe sb
Sound Status:
=============
The status of sound may be read/checked by:
cat /proc/sound
cat /dev/sndstat
cat (anyfile).au >/dev/audio
The status of the modules and which modules depend on
which other modules may be checked by:
/sbin/lsmod
/sbin/lsmod should show something like the following:
sb 26280 0
uart401 5640 0 [sb]
sound 57112 0 [sb uart401]
soundlow 208 0 [sound]
soundcore 1968 8 [sb sound]
Removing Sound:
===============
Sound may be removed by using /sbin/rmmod in the reverse order
in which you load the modules. Note, if a program has a sound device
open (e.g., xmixer), that module (and the modules on which it
depends) may not be unloaded.
For example, I use the following to remove my Soundblaster (rmmod
in the reverse order in which I loaded the modules):
/sbin/rmmod sb
/sbin/rmmod uart401
/sbin/rmmod sound
/sbin/rmmod soundlow
/sbin/rmmod soundcore
Multiple Sound Cards:
=====================
The sound drivers will support multiple sound cards and there
are some great applications like multitrack that support them.
Typically, you need two sound cards of different types. Note, this
uses more precious interrupts and DMA channels and sometimes
can be a configuration nightmare. I have heard reports of 3-4
sound cards (typically I only use 2).
On my machine I have two sound cards (cs4232 and Soundblaster Vibra
16). By loading sound as modules, I can control which is the first
sound device (/dev/dsp, /dev/audio, /dev/mixer) and which is
the second. Normally, the cs4232 (Dell sound on the motherboard)
would be the first sound device, but I prefer the Soundblaster.
All you have to do is to load the one you want as /dev/dsp
first (in my case "sb") and then load the other one
(in my case "cs4232").
Warning: I have never been able to get two PnP sound cards of the
same type to load at the same time. I have tried this several times
with the Soundblaster Vibra 16 cards. OSS has indicated that this
is a PnP problem.... If anyone has any luck doing this, please
send me an E-MAIL. PCI sound cards should not have this problem.
Sound Problems:
===============
First RTFM (including the troubleshooting section
in the Sound-HOWTO).
1) If you are having problems loading the modules (for
example, if you get device conflict errors) try the
following:
A) If you have Win95 or NT on the same computer,
write down what addresses, IRQ, and DMA channels
those were using for the same hardware. You probably
can use these addresses, IRQs, and DMA channels.
B) Check (cat) /proc/interrupts, /proc/ioports,
and /proc/dma. Are you trying to use an address,
IRQ or DMA port that another device is using?
C) Check (cat) /proc/sys/pnp (if this exists, you
may need a kernel patch to get this device).
D) Inspect your /var/log/messages file. Often that will
indicate what IRQ or IO port could not be obtained
E) Try another port or IRQ. Note this may involve
using the PnP tools to move the sound card to
another location.
2) If you get motorboating (the same sound or part of a
sound clip repeated), you probably have either an IRQ
or DMA conflict. Move the card to another address. This
has happened to me when playing long files when I had
an IRQ conflict.
3) Ask for help on the sound list or send E-MAIL to the
sound driver author/maintainer.
4) Turn on debug in drivers/sound/sound_config.h (DEB, DDB, MDB).
Configuring Sound:
==================
There are several ways of configuring your sound:
1) Hardcoded in the kernel at compile time (not applicable when
using sound modules). This was the OLD way!
2) On the command line when using insmod.
3) In /etc/conf.modules when using modprobe.
4) Via Red Hat's /usr/sbin/sndconfig program (text based).
5) Via the OSS soundconf program (with the commercial version
of the OSS driver.
And I am sure, several other ways.
Anyone want to write a linuxconf module for configuring sound?
For More Information (RTFM):
============================
1) Information on kernel modules: linux/Documentation/modules.txt
and manual pages for insmod and modprobe.
2) Information on PnP, RTFM manual pages for isapnp.
3) Sound-HOWTO and Sound-Playing-HOWTO.
4) OSS's WWW site at http://www.opensound.com.
5) All the files in linux/Documentation/sound.
6) The comments and code in linux/drivers/sound.
7) The sndconfig and rhsound documentation from Red Hat.
8) The Linux-sound mailing list: sound-list@redhat.com
Contact Information:
====================
Wade Hampton: (whampton@staffnet.com)
|
