Documentation/sound/alsa-configuration.rst

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==============================================================
Advanced Linux Sound Architecture - Driver Configuration guide
==============================================================


Kernel Configuration
====================

To enable ALSA support you need at least to build the kernel with
primary sound card support (``CONFIG_SOUND``).  Since ALSA can emulate
OSS, you don't have to choose any of the OSS modules.

Enable "OSS API emulation" (``CONFIG_SND_OSSEMUL``) and both OSS mixer
and PCM supports if you want to run OSS applications with ALSA.

If you want to support the WaveTable functionality on cards such as
SB Live! then you need to enable "Sequencer support"
(``CONFIG_SND_SEQUENCER``).

To make ALSA debug messages more verbose, enable the "Verbose printk"
and "Debug" options.  To check for memory leaks, turn on "Debug memory"
too.  "Debug detection" will add checks for the detection of cards.

Please note that all the ALSA ISA drivers support the Linux isapnp API
(if the card supports ISA PnP).  You don't need to configure the cards
using isapnptools.


Module parameters
=================

The user can load modules with options. If the module supports more than
one card and you have more than one card of the same type then you can
specify multiple values for the option separated by commas.


Module snd
----------

The core ALSA module.  It is used by all ALSA card drivers.
It takes the following options which have global effects.

major
    major number for sound driver;
    Default: 116
cards_limit
    limiting card index for auto-loading (1-8);
    Default: 1;
    For auto-loading more than one card, specify this option
    together with snd-card-X aliases.
slots
    Reserve the slot index for the given driver;
    This option takes multiple strings.
    See `Module Autoloading Support`_ section for details.
debug
    Specifies the debug message level;
    (0 = disable debug prints, 1 = normal debug messages,
    2 = verbose debug messages);
    This option appears only when ``CONFIG_SND_DEBUG=y``.
    This option can be dynamically changed via sysfs
    /sys/module/snd/parameters/debug file.
  
Module snd-pcm-oss
------------------

The PCM OSS emulation module.
This module takes options which change the mapping of devices.

dsp_map
    PCM device number maps assigned to the 1st OSS device;

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