1Introduction	Notes on Modular Sound Drivers and Soundcore
2Wade Hampton 
32/14/2001
4
5Purpose:  
6========
7This document provides some general notes on the modular 
8sound drivers and their configuration, along with the 
9support modules sound.o and soundcore.o.
10
11Note, some of this probably should be added to the Sound-HOWTO!
12
13Note, soundlow.o was present with 2.2 kernels but is not 
14required for 2.4.x kernels.  References have been removed
15to this.
16
17
18Copying:
19========
20none
21
22
23History:
24========
250.1.0  11/20/1998  First version, draft
261.0.0  11/1998     Alan Cox changes, incorporation in 2.2.0
27                   as Documentation/sound/oss/Introduction
281.1.0  6/30/1999   Second version, added notes on making the drivers,
29                   added info on multiple sound cards of similar types,]
30                   added more diagnostics info, added info about esd.
31                   added info on OSS and ALSA.
321.1.1  19991031	   Added notes on sound-slot- and sound-service.
33			(Alan Cox)
341.1.2  20000920    Modified for Kernel 2.4 (Christoph Hellwig)
351.1.3  20010214    Minor notes and corrections (Wade Hampton)
36                   Added examples of sound-slot-0, etc.
37
38
39Modular Sound Drivers:
40======================
41
42Thanks to the GREAT work by Alan Cox (alan@lxorguk.ukuu.org.uk),
43
44[And Oleg Drokin, Thomas Sailer, Andrew Veliath and more than a few 
45 others - not to mention Hannu's original code being designed well
46 enough to cope with that kind of chopping up](Alan)
47
48the standard Linux kernels support a modular sound driver.  From
49Alan's comments in linux/drivers/sound/README.FIRST:
50
51  The modular sound driver patches were funded by Red Hat Software 
52  (www.redhat.com). The sound driver here is thus a modified version of 
53  Hannu's code. Please bear that in mind when considering the appropriate
54  forums for bug reporting.
55
56The modular sound drivers may be loaded via insmod or modprobe.  
57To support all the various sound modules, there are two general 
58support modules that must be loaded first:
59 
60   soundcore.o:   Top level handler for the sound system, provides
61                  a set of functions for registration of devices
62                  by type.
63
64   sound.o:       Common sound functions required by all modules.
65
66For the specific sound modules (e.g., sb.o for the Soundblaster), 
67read the documentation on that module to determine what options
68are available, for example IRQ, address, DMA.
69
70Warning, the options for different cards sometime use different names 
71for the same or a similar feature (dma1= versus dma16=).  As a last 
72resort, inspect the code (search for module_param).
73
74Notes:
75
761.  There is a new OpenSource sound driver called ALSA which is
77    currently under development:  http://www.alsa-project.org/
78    The ALSA drivers support some newer hardware that may not 
79    be supported by this sound driver and also provide some 
80    additional features.
81
822.  The commercial OSS driver may be obtained from the site:
83    http://www.opensound.com.  This may be used for cards that
84    are unsupported by the kernel driver, or may be used
85    by other operating systems.  
86
873.  The enlightenment sound daemon may be used for playing
88    multiple sounds at the same time via a single card, eliminating
89    some of the requirements for multiple sound card systems.  For
90    more information, see:  http://www.tux.org/~ricdude/EsounD.html  
91    The "esd" program may be used with the real-player and mpeg 
92    players like mpg123 and x11amp.  The newer real-player 
93    and some games even include built-in support for ESD!
94
95
96Building the Modules:
97=====================
98
99This document does not provide full details on building the 
100kernel, etc.  The notes below apply only to making the kernel
101sound modules.   If this conflicts with the kernel's README,
102the README takes precedence. 
103
1041.  To make the kernel sound modules, cd to your /usr/src/linux
105    directory (typically) and type make config, make menuconfig, 
106    or make xconfig (to start the command line, dialog, or x-based
107    configuration tool).  
108
1092.  Select the Sound option and a dialog will be displayed.  
110
1113.  Select M (module) for "Sound card support".
112
1134.  Select your sound driver(s) as a module.  For ProAudio, Sound
114    Blaster, etc., select M (module) for OSS sound modules.
115    [thanks to Marvin Stodolsky <stodolsk@erols.com>]A
116
1175.  Make the kernel (e.g., make bzImage), and install the kernel.
118
1196.  Make the modules and install them (make modules; make modules_install).
120
121Note, for 2.5.x kernels, make sure you have the newer module-init-tools 
122installed or modules will not be loaded properly.  2.5.x requires an
123updated module-init-tools.
124
125
126Plug and Play (PnP:
127===================
128
129If the sound card is an ISA PnP card, isapnp may be used
130to configure the card.  See the file isapnp.txt in the 
131directory one level up (e.g., /usr/src/linux/Documentation).
132
133Also the 2.4.x kernels provide PnP capabilities, see the 
134file NEWS in this directory.
135
136PCI sound cards are highly recommended, as they are far 
137easier to configure and from what I have read, they use
138less resources and are more CPU efficient.
139
140
141INSMOD:
142=======
143
144If loading via insmod, the common modules must be loaded in the 
145order below BEFORE loading the other sound modules.  The card-specific
146modules may then be loaded (most require parameters).  For example,
147I use the following via a shell script to load my SoundBlaster:
148
149SB_BASE=0x240
150SB_IRQ=9
151SB_DMA=3
152SB_DMA2=5
153SB_MPU=0x300
154#
155echo Starting sound
156/sbin/insmod soundcore
157/sbin/insmod sound  
158#
159echo Starting sound blaster....
160/sbin/insmod uart401
161/sbin/insmod sb io=$SB_BASE irq=$SB_IRQ dma=$SB_DMA dma16=$SB_DMA2 mpu_io=$SB_MP
162
163When using sound as a module, I typically put these commands
164in a file such as /root/soundon.sh.
165
166
167MODPROBE:
168=========
169
170If loading via modprobe, these common files are automatically loaded when
171requested by modprobe.  For example, my /etc/modprobe.d/oss.conf contains:
172
173alias sound sb 
174options sb io=0x240 irq=9 dma=3 dma16=5 mpu_io=0x300
175
176All you need to do to load the module is:
177
178	/sbin/modprobe sb
179
180
181Sound Status:
182=============
183
184The status of sound may be read/checked by:
185        cat (anyfile).au >/dev/audio
186
187[WWH:  This may not work properly for SoundBlaster PCI 128 cards
188such as the es1370/1 (see the es1370/1 files in this directory) 
189as they do not automatically support uLaw on /dev/audio.]
190
191The status of the modules and which modules depend on 
192which other modules may be checked by:
193	/sbin/lsmod
194
195/sbin/lsmod should show something like the following:
196	sb                     26280   0 
197	uart401                 5640   0  [sb]
198	sound                  57112   0  [sb uart401]
199	soundcore               1968   8  [sb sound]
200
201
202Removing Sound: 
203=============== 
204
205Sound may be removed by using /sbin/rmmod in the reverse order
206in which you load the modules.  Note, if a program has a sound device
207open (e.g., xmixer), that module (and the modules on which it 
208depends) may not be unloaded.
209
210For example, I use the following to remove my Soundblaster (rmmod
211in the reverse order in which I loaded the modules):
212
213/sbin/rmmod sb
214/sbin/rmmod uart401
215/sbin/rmmod sound
216/sbin/rmmod soundcore
217
218When using sound as a module, I typically put these commands
219in a script such as /root/soundoff.sh.
220
221
222Removing Sound for use with OSS: 
223================================ 
224
225If you get really stuck or have a card that the kernel modules
226will not support, you can get a commercial sound driver from
227http://www.opensound.com.  Before loading the commercial sound
228driver, you should do the following:
229
2301.  remove sound modules (detailed above)
2312.  remove the sound modules from /etc/modprobe.d/*.conf
2323.  move the sound modules from /lib/modules/<kernel>/misc
233    (for example, I make a /lib/modules/<kernel>/misc/tmp
234    directory and copy the sound module files to that 
235    directory).
236
237
238Multiple Sound Cards:
239=====================
240
241The sound drivers will support multiple sound cards and there
242are some great applications like multitrack that support them.  
243Typically, you need two sound cards of different types.  Note, this
244uses more precious interrupts and DMA channels and sometimes 
245can be a configuration nightmare.  I have heard reports of 3-4
246sound cards (typically I only use 2).  You can sometimes use
247multiple PCI sound cards of the same type.
248
249On my machine I have two sound cards (cs4232 and Soundblaster Vibra
25016).  By loading sound as modules, I can control which is the first
251sound device (/dev/dsp, /dev/audio, /dev/mixer) and which is 
252the second.  Normally, the cs4232 (Dell sound on the motherboard) 
253would be the first sound device, but I prefer the Soundblaster.  
254All you have to do is to load the one you want as /dev/dsp 
255first (in my case "sb") and then load the other one
256(in my case "cs4232").
257
258If you have two cards of the same type that are jumpered 
259cards or different PnP revisions, you may load the same 
260module twice.  For example, I have a SoundBlaster vibra 16
261and an older SoundBlaster 16 (jumpers).  To load the module
262twice, you need to do the following:
263
2641.  Copy the sound modules to a new name.  For example
265    sb.o could be copied (or symlinked) to sb1.o for the
266    second SoundBlaster.
267
2682.  Make a second entry in /etc/modprobe.d/*conf, for example,
269    sound1 or sb1.  This second entry should refer to the
270    new module names for example sb1, and should include
271    the I/O, etc. for the second sound card.
272
2733.  Update your soundon.sh script, etc.
274
275Warning:  I have never been able to get two PnP sound cards of the
276same type to load at the same time.  I have tried this several times
277with the Soundblaster Vibra 16 cards.  OSS has indicated that this
278is a PnP problem....  If anyone has any luck doing this, please 
279send me an E-MAIL.  PCI sound cards should not have this problem.a
280Since this was originally release, I have received a couple of 
281mails from people who have accomplished this!
282
283NOTE: In Linux 2.4 the Sound Blaster driver (and only this one yet)
284supports multiple cards with one module by default.
285Read the file 'Soundblaster' in this directory for details.
286
287
288Sound Problems:
289===============
290
291First RTFM (including the troubleshooting section 
292in the Sound-HOWTO). 
293
2941)  If you are having problems loading the modules (for
295    example, if you get device conflict errors) try the
296    following:
297
298  A)  If you have Win95 or NT on the same computer,  
299      write down what addresses, IRQ, and DMA channels
300      those were using for the same hardware.  You probably 
301      can use these addresses, IRQs, and DMA channels.
302      You should really do this BEFORE attempting to get
303      sound working!
304  
305  B)  Check (cat) /proc/interrupts, /proc/ioports,
306      and /proc/dma.  Are you trying to use an address,
307      IRQ or DMA port that another device is using?
308  
309  C)  Check (cat) /proc/isapnp
310  
311  D)  Inspect your /var/log/messages file.  Often that will 
312      indicate what IRQ or IO port could not be obtained.
313  
314  E)  Try another port or IRQ.  Note this may involve 
315      using the PnP tools to move the sound card to 
316      another location.  Sometimes this is the only way 
317      and it is more or less trial and error.
318
3192)  If you get motor-boating (the same sound or part of a 
320    sound clip repeated), you probably have either an IRQ
321    or DMA conflict.  Move the card to another IRQ or DMA
322    port.  This has happened to me when playing long files 
323    when I had an IRQ conflict.
324
3253.  If you get dropouts or pauses when playing high sample
326    rate files such as using mpg123 or x11amp/xmms, you may 
327    have too slow of a CPU and may have to use the options to 
328    play the files at 1/2 speed.  For example, you may use
329    the -2 or -4 option on mpg123.  You may also get this
330    when trying to play mpeg files stored on a CD-ROM
331    (my Toshiba T8000 PII/366 sometimes has this problem).
332
3334.  If you get "cannot access device" errors, your /dev/dsp
334    files, etc. may be set to owner root, mode 600.  You 
335    may have to use the command:
336      chmod 666 /dev/dsp /dev/mixer /dev/audio
337
3385.  If you get "device busy" errors, another program has the
339    sound device open.  For example, if using the Enlightenment
340    sound daemon "esd", the "esd" program has the sound device.
341    If using "esd", please RTFM the docs on ESD.  For example,
342    esddsp <program> may be used to play files via a non-esd
343    aware program.
344
3456)  Ask for help on the sound list or send E-MAIL to the
346    sound driver author/maintainer.
347
3487)  Turn on debug in drivers/sound/sound_config.h (DEB, DDB, MDB).
349
3508)  If the system reports insufficient DMA memory then you may want to
351    load sound with the "dmabufs=1" option. Or in /etc/conf.modules add
352	
353	preinstall sound dmabufs=1
354
355    This makes the sound system allocate its buffers and hang onto them.
356
357    You may also set persistent DMA when building a 2.4.x kernel.
358
359
360Configuring Sound:
361==================
362
363There are several ways of configuring your sound:
364
3651)  On the kernel command line (when using the sound driver(s)
366    compiled in the kernel). Check the driver source and
367    documentation for details.
368
3692)  On the command line when using insmod or in a bash script
370    using command line calls to load sound.
371
3723)  In /etc/modprobe.d/*conf when using modprobe.
373
3744)  Via Red Hat's GPL'd /usr/sbin/sndconfig program (text based).
375
3765)  Via the OSS soundconf program (with the commercial version
377    of the OSS driver.
378
3796)  By just loading the module and let isapnp do everything relevant
380    for you. This works only with a few drivers yet and - of course -
381    only with isapnp hardware.
382
383And I am sure, several other ways.  
384
385Anyone want to write a linuxconf module for configuring sound?
386
387
388Module Loading:
389===============
390
391When a sound card is first referenced and sound is modular, the sound system
392will ask for the sound devices to be loaded. Initially it requests that
393the driver for the sound system is loaded. It then will ask for 
394sound-slot-0, where 0 is the first sound card. (sound-slot-1 the second and
395so on). Thus you can do
396
397alias sound-slot-0 sb
398
399To load a soundblaster at this point. If the slot loading does not provide
400the desired device - for example a soundblaster does not directly provide
401a midi synth in all cases then it will request "sound-service-0-n" where n
402is
403
404  0	Mixer
405
406  2  	MIDI
407
408  3, 4	DSP audio
409
410
411For example, I use the following to load my Soundblaster PCI 128
412(ES 1371) card first, followed by my SoundBlaster Vibra 16 card,
413then by my TV card:
414
415# Load the Soundblaster PCI 128 as /dev/dsp, /dev/dsp1, /dev/mixer
416alias sound-slot-0 es1371
417
418# Load the Soundblaster Vibra 16 as /dev/dsp2, /dev/mixer1
419alias sound-slot-1 sb
420options sb io=0x240 irq=5 dma=1 dma16=5 mpu_io=0x330
421
422# Load the BTTV (TV card) as /dev/mixer2
423alias sound-slot-2 bttv
424alias sound-service-2-0 tvmixer
425
426pre-install bttv  modprobe tuner ; modprobe tvmixer
427pre-install tvmixer modprobe msp3400; modprobe tvaudio 
428options tuner debug=0 type=8 
429options bttv  card=0 radio=0 pll=0
430
431
432For More Information (RTFM):
433============================
4341)  Information on kernel modules: manual pages for insmod and modprobe.
435
4362)  Information on PnP, RTFM manual pages for isapnp.
437
4383)  Sound-HOWTO and Sound-Playing-HOWTO.
439
4404)  OSS's WWW site at http://www.opensound.com.
441
4425)  All the files in Documentation/sound.
443
4446)  The comments and code in linux/drivers/sound.
445
4467)  The sndconfig and rhsound documentation from Red Hat.
447
4488)  The Linux-sound mailing list:  sound-list@redhat.com.
449
4509)  Enlightenment documentation (for info on esd)
451    http://www.tux.org/~ricdude/EsounD.html.
452
45310) ALSA home page:  http://www.alsa-project.org/
454
455
456Contact Information:
457====================
458Wade Hampton:  (whampton@staffnet.com)
459
460