Langue: en

Version: 326856 (ubuntu - 08/07/09)

Section: 4 (Pilotes et protocoles réseau)

BSD mandoc


snd_hda - Intel High Definition Audio bridge device driver


To compile this driver into the kernel, place the following lines in your kernel configuration file:
device sound device snd_hda

Alternatively, to load the driver as a module at boot time, place the following line in loader.conf5:



The bridge device driver allows the generic audio driver, sound(4), to attach to Intel High Definition Audio devices. The driver supports hardware that conforms with revision 1.0 of the Intel High Definition Audio specification and tries to behave much like the Microsoft Universal Audio Architecture (UAA) draft (revision 0.7b) for handling audio devices. HDA acts like a primary bus, similar to miibus(4), for handling various child buses such as audio, modem and HDMI (High Definition Multimedia Interface). Only audio is implemented in the driver.

The High Definition (HD) Audio specification was developed by Intel as the logical successor of the old AC'97 specification and has several advantages, such as higher bandwidth which allows more channels and more detailed formats, support for several logical audio devices, and general purpose DMA channels.

The HDA specification defines the register-level interface, physical link characteristics, codec programming models, and codec architectural components. This specification is intended for both device driver developers and hardware component designers.

Boot-time Configuration

The following variables are available at boot-time through the device.hints5 file:
Configures a range of possible options. Possible values are: ``dmapos '' ``eapdinv '' ``gpio0 '' ``gpio1 '' ``gpio2 '' ``gpio3 '' ``gpio4 '' ``gpio5 '' ``gpio6 '' ``gpio7 '' ``gpioflush '' ``ivref '' ``ivref50 '' ``ivref80 '' ``ivref100 '' ``fixedrate '' ``forcestereo '' ``ovref '' ``ovref50 '' ``ovref80 '' ``ovref100 '' ``softpcmvol '' and ``vref '' An option prefixed with ``no '' such as ``nofixedrate '' will do the opposite and takes precedence. Options can be separated by whitespace and commas.

Runtime Configuration

The following sysctl(8) variables are available in addition to those available to all sound(4) devices:
Experimental polling mode, where the driver operates by querying the device state on each tick using callout(9). Polling is disabled by default. Do not enable it unless you are facing weird interrupt problems or if the device cannot generate interrupts at all.


The driver supports the following audio chipsets:

Generic audio chipsets compatible with the Intel HDA specification should work, but have not been verified yet. The following codecs have been verified to work:


sound(4), device.hints5, loader.conf5, sysctl(8)


The device driver first appeared in Fx 6.3 .


An -nosplit The driver was written by An Stephane E. Potvin Aq and An Ariff Abdullah Aq . This manual page was written by An Joel Dahl Aq .


There are a couple of missing features, such as support for Digital S/PDIF and multichannel output.

A few Hardware/OEM vendors tend to screw up BIOS settings, thus rendering the driver useless, which usually results in a state where the driver seems to attach and work, but without any sound.