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Using AVIRT
===================================
## Introduction
## Table of Contents
1. [Load/Unload AVIRT](#un-load-avirt)
2. [Configuring AVIRT](#configuring-avirt)
<a name="un-load-avirt"/>
## Loading and Unloading AVIRT
### Load Out of Tree
As root, load the required `avirt_core.ko` and subsequent audio path.
As an example, the Dummy Audiopath is being loaded here.
```sh
insmod avirt_core.ko
insmod dummy/avirt_dummyap.ko
insmod loopback/avirt_loopbackap.ko
```
### Note:
The loading and unloading of drivers can be performed using the helper scripts.
To run, we must load the kernel modules using the `scripts/load.sh` script:
```sh
$ ./scripts/load.sh
```
To unload the drivers use:
```sh
$ ./scripts/unload.sh
```
### Load In Tree
#### Note:
Either build the module in tree, or you can copy the modules manually and then run `depmod` to generate dependencies.
For example, in AGL:
```sh
mkdir -p /lib/modules/$(uname -r)/extra
cp avirt_core.ko avirt_dummyap.ko avirt_loopbackap.ko /lib/modules/$(uname -r)/extra
depmod
```
Once the modules are in place, we can load the modules using:
```sh
modprobe avirt_core
modprobe avirt_dummyap
modprobe avirt_loopbackap
```
<a name="configure-avirt" />
## Configuring AVIRT
AVIRT is configured using configfs.
### Note:
A sample script for the following is supplied inside the `scripts` folder.
First, verify the kernel supports the use of configfs.
```sh
fgrep configfs /proc/filesystems
```
the expected output is:
```
nodev configfs
```
Once confirmed, we can mount the configfs at the conventional point:
```sh
# Check configfs is mounted on the system
mkdir -p /config
mount -t configfs none /config
```
Finally, we can configure AVIRT:
```sh
# Set up each of the cards channels
mkdir /config/avirt/streams/playback_media
echo "2">/config/avirt/streams/playback_media/channels
echo "ap_dummy">/config/avirt/streams/playback_media/map
mkdir /config/avirt/streams/playback_navigation
echo "1">/config/avirt/streams/playback_navigation/channels
echo "ap_dummy">/config/avirt/streams/playback_navigation/map
mkdir /config/avirt/streams/playback_emergency
echo "1">/config/avirt/streams/playback_emergency/channels
echo "ap_dummy">/config/avirt/streams/playback_emergency/map
mkdir /config/avirt/streams/capture_voice
echo "1">/config/avirt/streams/capture_voice/channels
echo "ap_dummy">/config/avirt/streams/capture_voice/map
# Finally, seal the card, and initiate configuration
echo "1">/config/avirt/streams/sealed
```
Alternatively, the test script at `scripts/test_configfs.sh` can be used.
### Note:
A simplified helper library, libavirt, is available [here](https://github.com/fiberdyne/libavirt).
Please refer to the readme in libavirt for further details.
|
