.. zephyr:code-sample:: ipm-ivshmem
:name: IPM over IVSHMEM
:relevant-api: ipm_interface
Implement inter-processor mailbox (IPM) over IVSHMEM (Inter-VM shared memory)
Prerequisites
*************
* QEMU needs to available.
ivshmem-server needs to be available and running. The server is available in
Zephyr SDK or pre-built in some distributions. Otherwise, it is available in
QEMU source tree.
ivshmem-client needs to be available as it is employed in this sample as an
external application. The same conditions of ivshmem-server apply to the
ivshmem-server, as it is also available via QEMU.
Preparing IVSHMEM server
************************
#. The ivshmem-server utility for QEMU can be found into the Zephyr SDK
directory, in:
``/path/to/your/zephyr-sdk/zephyr-<version>/sysroots/x86_64-pokysdk-linux/usr/xilinx/bin/``
#. You may also find ivshmem-client utility, it can be useful to check if everything works
as expected.
#. Run ivshmem-server. For the ivshmem-server, both number of vectors and
shared memory size are decided at run-time (when the server is executed).
For Zephyr, the number of vectors and shared memory size of ivshmem are
decided at compile-time and run-time, respectively. For Arm64 we use
vectors == 2 for the project configuration in this sample. Here is an example:
.. code-block:: console
# n = number of vectors
$ sudo ivshmem-server -n 2
$ *** Example code, do not use in production ***
#. Appropriately set ownership of ``/dev/shm/ivshmem`` and
``/tmp/ivshmem_socket`` for your deployment scenario. For instance:
.. code-block:: console
$ sudo chgrp $USER /dev/shm/ivshmem
$ sudo chmod 060 /dev/shm/ivshmem
$ sudo chgrp $USER /tmp/ivshmem_socket
$ sudo chmod 060 /tmp/ivshmem_socket
Building and Running
********************
After getting QEMU ready to go, first create two output folders, so open two terminals
and create them, these folders will receive the output of Zephyr west commands:
.. code-block:: console
$ mkdir -p path/to/instance_1
On another terminal window do:
.. code-block:: console
$ mkdir -p path/to/instance_2
Then build the sample as follows, don't forget, two builds are necessary
to test this sample, so append the option ``-d path/to/instance_1`` and
on the other terminal window do the same, that is it ``-d path/to/instance_2``
.. zephyr-app-commands::
:zephyr-app: samples/drivers/ipm/ipm_ivshmem
:board: qemu_cortex_a53
:goals: build
:compact:
To run both QEMU sides, repeat the west build command followed
by ``-d path/to/instance_x`` where x is 1 or 2 depending on the
terminal window, using the run target:
.. zephyr-app-commands::
:zephyr-app: samples/drivers/ipm/ipm_ivshmem
:board: qemu_cortex_a53
:goals: run
:compact:
Expected output
***************
On the console just use the ``ivshmem_ipm_send`` command
followed by the destination peer-id, to get the peer-id destination
go to the other terminal window and check with ``ivshmem`` command:
.. code-block:: console
*** Booting Zephyr OS build zephyr-v3.4.0-974-g7fba7d395750 ***
uart:~$ ivshmem
IVshmem up and running:
Shared memory: 0xafa00000 of size 4194304 bytes
Peer id: 12
Notification vectors: 2
uart:~$
For example one of the instances has the peer-id 12, so go the other
instance and use the command to send the IPM notification followed
by this peer-id:
.. code-block:: console
*** Booting Zephyr OS build zephyr-v3.4.0-974-g7fba7d395750 ***
uart:~$ ivshmem
IVshmem up and running:
Shared memory: 0xafa00000 of size 4194304 bytes
Peer id: 11
Notification vectors: 2
uart:~$ ivshmem_ipm_send 12
Then go back to the other terminal window where user may see the reception
of the notification on the terminal:
.. code-block:: console
uart:~$ ivshmem
IVshmem up and running:
Shared memory: 0xafa00000 of size 4194304 bytes
Peer id: 12
Notification vectors: 2
uart:~$ Received IPM notification over IVSHMEM
243eb36b18