Console audio control ALSA interface


Linux Kernel Configuration
└─>Device Drivers
└─>X86 Platform Specific Device Drivers
└─>Advanced Linux Sound Architecture
└─>Advanced Linux Sound Architecture
└─>Advanced Linux Sound Architecture
└─>Console audio control ALSA interface
In linux kernel since version 2.6.33 (release Date: 2010-02-24)  
Enables monitoring of the built-in console audio output control
(headphone and speakers), which is operated by the mute and (in
some ThinkPad models) volume hotkeys.

If this option is enabled, ThinkPad-ACPI will export an ALSA card
with a single read-only mixer control, which should be used for
on-screen-display feedback purposes by the Desktop Environment.

Optionally, the driver will also allow software control (the
ALSA mixer will be made read-write). Please refer to the driver
documentation for details.

All IBM models have both volume and mute control. Newer Lenovo
models only have mute control (the volume hotkeys are just normal
keys and volume control is done through the main HDA mixer).