Intel ADSP cAVS and ACE

Intel’s Audio and Digital Signal Processing (ADSP) hardware offerings include the Converged Audio Voice Speech (cAVS) series and its successor, the Audio and Context Engine (ACE). These Xtensa-based ADSPs can be integrated into a variety of Intel products. The below table lists (some of) the Intel microprocessor(s) that each version of the Intel ADSP is compatible with.

ADSP	Microprocessor
cAVS 1.5	Apollo Lake
cAVS 1.8	Whiskey Lake
cAVS 2.5	Tiger Lake
ACE 1.5	Meteor Lake

Intel open-sources firmware for its ADSP hardware under the Sound Open Firmware (SOF) project. SOF can be built with either Zephyr or Cadence’s proprietary Xtensa OS (XTOS) and run on a variety of Intel and non-Intel platforms.

The Intel UP Xtreme product line has the publicly available reference boards for Zephyr’s Intel ADSP support. This guide uses the UP Xtreme i11-0001 series (Intel ADSP CAVS 2.5) board as an example. However, the instructions are generic and will work on other boards unless otherwise stated. You will be referred to the documentation for your specific board in these cases.

System requirements

Setting Up Target Board

You can only flash Zephyr to the ADSP by using Zephyr’s Python tool in a Linux host running on the board’s main CPU. It is possible (and recommended) for users to build the binary locally on their development machine and flash remotely, but the board itself must be capable of running the Python script that receives the binary sent over the network by West and flashes it. You should install a version of Linux that supports or comes with the current version of Python that Zephyr requires. Consider using Ubuntu 20.04, which comes with Python 3.8 installed.

Note that if you plan to use SOF on your board, you will need to build and install the modified Linux SOF kernel instead of the default kernel. It is recommended you follow the SOF instructions to build and run SOF on Zephyr.

UP Xtreme users can refer to the UP Community wiki for help installing a Linux operating system on their board.

Signing Tool

As firmware binary signing is mandatory on Intel products from Skylake onwards, you will also need to set up the SOF rimage signing tool and key.

cd zephyrproject
west config manifest.project-filter -- +sof
west update
cd modules/audio/sof/tools/rimage

Follow the instructions in the rimage README.md to build the tool on your system. You can either copy the executable to a directory in your PATH or use west config rimage.path /path/to/rimage-build/rimage; see more details in the output of west sign -h. Running directly from the build directory makes you less likely to use an obsolete rimage version by mistake.

Platform-specific configuration files are located in the rimage/config/ subdirectory. For a different configuration directory you can use: west config build.cmake-args -- -DRIMAGE_CONFIG_PATH=/path/to/my/rimage/config.

Xtensa Toolchain (Optional)

The Zephyr SDK provides GCC-based toolchains necessary to build Zephyr for the cAVS and ACE boards. However, users seeking greater levels of optimization may desire to build with the proprietary Xtensa toolchain distributed by Cadence instead. The following instructions assume you have purchased and installed the toolchain(s) and core(s) for your board following their instructions.

First, make sure to set the $HOME/.flexlmrc file or XTENSAD_LICENSE_FILE variable as instructed by Cadence. Next, set the following environment variables:

export XTENSA_TOOLCHAIN_PATH=$HOME/xtensa/XtDevTools/install/tools
export XTENSA_BUILDS_DIR=$XTENSA_TOOLCHAIN_PATH/../builds
export ZEPHYR_TOOLCHAIN_VARIANT=xcc
export TOOLCHAIN_VER=RG-2017.8-linux
export XTENSA_CORE=cavs2x_LX6HiFi3_2017_8

The bottom three variables are specific to each version of cAVS / ACE; refer to your board’s documentation for their values.

Programming and Debugging

Building

Build as usual.

# From the root of the zephyr repository
west build -b intel_adsp/cavs25 samples/hello_world

Signing

west build tries to sign the binary at the end of the build. If you need to sign the binary yourself, you can invoke west sign directly. Read the west logs to find the west sign invocation; you can copy and modify the command logged for your own purposes. Run west sign -h for more details.

The build tries to provide as many default rimage parameters are possible. If needed, there are several ways to override them depending on your specific situation and use case. They’re often not mutually exclusive but to avoid undocumented rimage precedence rules it’s best to use only one way at a time.

• For local, interactive use prefer rimage.extra-args in west config, see west sign -h. The WEST_CONFIG_LOCAL environment variable can point at a different west configuration file if needed.

• You can add or overwrite a $platform.toml file(s) in your rimage/config/ directory

• For board-specific needs you can define WEST_SIGN_OPTS in boards/my/board/board.cmake, see example in soc/intel/adsp/common/CMakeLists.txt

Starting with Zephyr 3.6.0, west flash does not invoke west sign anymore and you cannot pass rimage parameters to west flash anymore. To see an up-to-date list of all arguments to the Intel ADSP runner, run the following after you have built the binary:

west flash --context

Remote Flashing to cAVS-based ADSP

As mentioned previously, the recommended way to run and monitor the output of Zephyr on cAVS boards is remotely. The Linux host on the main CPU may freeze up and need to be restarted if a flash or runtime error occurs on the ADSP. From this point onward, we will refer to the board as the “remote host” and your development machine as the “local host”.

Copy the below scripts to the cAVS board. soc/intel/intel_adsp/tools/remote-fw-service.py will receive the binary sent over the network by West and invoke soc/intel/intel_adsp/tools/cavstool.py (referred to as the “cAVS tool”), which performs the flash and captures the log. Start remote-fw-service.py.

scp -r $ZEPHYR_BASE/soc/intel/intel_adsp/tools/cavstool.py username@remotehostname
scp -r $ZEPHYR_BASE/soc/intel/intel_adsp/tools/remote-fw-service.py username@remotehostname
ssh username@remotehostname
sudo ./remote-fw-service.py

remote-fw-service.py uses ports 9999 and 10000 on the remote host to communicate. It forwards logs collected by cavstool.py on port 9999 (referred to as its “log port”) and services requests on port 10000 (its “requests port”). When you run West or Twister on your local host, it sends requests using the soc/intel/intel_adsp/tools/cavstool_client.py script (referred to as “cAVS tool client”). It also uses ports 9999 and 10000 on your local host, so be sure those ports are free.

Flashing with West is simple.

west flash --remote-host remotehostname --pty remotehostname

Running tests with Twister is slightly more complicated.

twister -p intel_adsp/cavs25 --device-testing --device-serial-pty="$ZEPHYR_BASE/soc/intel/intel_adsp/tools/cavstool_client.py,-s,remotehostname,-l" --west-flash="--remote-host=remotehostname" -T samples/hello_world

If your network is set up such that the TCP connection from cavstool_client.py to remote-fw-service.py is forwarded through an intermediate host, you may need to tell cavstool_client.py to connect to different ports as well as a different hostname. You can do this by appending the port numbers to the intermediate host name.

west flash --remote-host intermediatehost:reqport --pty remotehostname:logport
twister -p intel_adsp/cavs25 --device-testing --device-serial-pty="$ZEPHYR_BASE/soc/intel/intel_adsp/tools/cavstool_client.py,-s,remotehostname:logport,-l" --west-flash="--remote-host=remotehostname:reqport" -T samples/hello_world

You can also save this information to a hardware map file and pass that to Twister.

twister -p intel_adsp/cavs25 --hardware-map cavs.map --device-testing -T samples/hello_world

Here’s a sample cavs.map:

- connected: true
  id: None
  platform: intel_adsp/cavs25
  product: None
  runner: intel_adsp
  serial_pty: "/home/zephyrus/zephyrproject/zephyr/soc/intel/intel_adsp/tools/cavstool_client.py,-s,remotehostname:logport,-l"
  runner_params:
  - --remote-host=remotehostname:reqport

Any of the arguments you would pass to Twister or West, you can pass with the hardware map. As mentioned previously, you can see the Intel ADSP runner arguments by passing the --context flag while flashing with West.

Refer to Test Runner (Twister) for more information on hardware maps.

Local Flashing to cAVS-based ADSP

You can also directly flash the signed binary with the cAVS tool on the board. This may be useful for debugging.

sudo ./cavstool.py zephyr.ri

You should see the following at the end of the log if you are successful:

***** Booting Zephyr OS vx.x.x-xxx-gxxxxxxxxxxxx *****
Hello World! intel_adsp

Flashing to ACE-based ADSP

Flashing is not yet supported for platforms with ACE-based ADSP, as these platforms are not yet publicly available.

Debugging

As Zephyr doesn’t (yet) support GDB for the Intel ADSP platforms, users are recommended to take advantage of Zephyr’s built-in Core Dump and Logging features.

Troubleshooting

You can pass verbose flags directly to the Intel ADSP scripts:

sudo ./remote-fw-service.py -v
sudo ./cavstool.py zephyr.ri -v

To see a list of their arguments:

sudo ./remote-fw-service.py --help
sudo ./cavstool.py --help

If flashing fails at west sign with errors related to unparsed keys, try reinstalling the latest version of the signing tool. For example:

error: 1 unparsed keys left in 'adsp'
error: 1 unparsed arrays left in 'adsp'

If you get an “Address already in use” error when starting remote-fw-service.py on the board, you may have another instance of the script running. Kill it.

$ sudo netstat -peanut | grep 9999
tcp   0   0 0.0.0.0:9999   0.0.0.0:*   LISTEN   0   289788   14795/python3
$ sudo kill 14795

If West or Twister successfully sign and establish TCP connections with remote-fw-service.py but hang with no output afterwards, there are two possibilities: either remote-fw-service.py failed to communicate, or cavstool.py failed to flash. Log into the remote host and check the output of remote-fw-service.py.

If a message about “incorrect communication” appears, you mixed up the port numbers for logging and requests in your command or hardware map. Switch them and try again.

ERROR:remote-fw:incorrect monitor communication!

If a “load failed” message appears, that means the flash failed. Examine the log of west flash and carefully check that the arguments to west sign are correct.

WARNING:cavs-fw:Load failed?  FW_STATUS = 0x81000012
INFO:cavs-fw:cAVS firmware load complete
--

Sometimes a flash failure or network miscommunication corrupts the state of the ADSP or remote-fw-service.py. If you are unable to identify a cause of repeated failures, try restarting the scripts and / or power cycling your board to reset the state.

Users - particularly, users of the Xtensa toolchain - should also consider clearing their Zephyr cache, as caching issues can occur from time to time. Delete the cache as well as any applicable build directories and start from scratch. You can try using the “pristine” option of West first, if you like.

rm -rf build twister-out*
rm -rf ~/.ccache ~/.cache/zephyr

Xtensa toolchain users can get more detailed logs from the license server by exporting FLEXLM_DIAGNOSTICS=3.