HAL bundle?

[Wouter1]

In old versions of this extension, there was a HAL bundle

Do we need this?

[Wouter1]

This code never triggered, Therefore it was removed a long time ago

[Wouter1]

In the Audio Device Driver Programming Guide of Apple, I read this

Sometimes you might have an audio device with properties that are not covered by what the Audio HAL specifies. For these situations, you can create a bundle that contains code implementing these device-specific properties on behalf of the Audio HAL. Then you can put this bundle in a location where it can be exported to user space. ... When a driver changes a property, it calls one of two ntification callbacks implemented by clients to notify them

When you have created a bundle, you usually install it inside your driver's kernel extension in /System/Library/Extensions.

HAL finds the bundle by looking in the I/O registry for two keys: kIOAudioEngineCoreAudioPlugInKey and kIOAudioDeviceLocalizedBundleKey

[Wouter1]

The key kIOAudioEngineCoreAudioPlugInKey is actually still set in EMUUSBAudioDevice.