Re: [PATCH 1/2] app/testpmd: add test for remote PD and CTX

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/1/2022 8:26 PM, Michael Baum wrote:
> Add mlx5 internal option in testpmd run-time function "port attach" to
> add another parameter named "mlx5_socket" for attaching port and add 2
> devargs before.
> 
> The arguments are "cmd_fd" and "pd_handle" using to import device
> created out of PMD. Testpmd application import it using IPC, and updates
> the devargs list before attaching.
> 
> The syntax is:
> 
>    testpmd > port attach (identifier) mlx5_socket=(path)
> 
> Where "path" is the IPC socket path agreed on the remote process.
> 
> Signed-off-by: Michael Baum <michaelba@nvidia.com>
> Acked-by: Matan Azrad <matan@nvidia.com>

<...>

> diff --git a/app/test-pmd/meson.build b/app/test-pmd/meson.build
> index 43130c8856..c4fd379e67 100644
> --- a/app/test-pmd/meson.build
> +++ b/app/test-pmd/meson.build
> @@ -73,3 +73,6 @@ endif
>   if dpdk_conf.has('RTE_NET_DPAA')
>       deps += ['bus_dpaa', 'mempool_dpaa', 'net_dpaa']
>   endif
> +if dpdk_conf.has('RTE_NET_MLX5')
> +    deps += 'net_mlx5'
> +endif

Is this patch introduce any build time dependency to mlx5
driver? If not this chunk should go to next patch, which
uses mlx5 PMD specific API.

<...>

> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> index 1083c6d538..d6490947c4 100644
> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> @@ -2127,6 +2127,46 @@ the mode and slave parameters must be given.
>      Done
>   
>   
> +port attach with mlx5 socket path
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +MLX5 internal option to attach a port specified by pci address or virtual device
> +args and add extra devargs to it, which is imported from external process::
> +
> +   testpmd> port attach (identifier) mlx5_socket=(path)
> +
> +where:
> +
> +* ``identifier``: pci address or virtual device args.
> +* ``path``: socket path to import arguments agreed by the external process.
> +
> +The mlx5 PMD enables to import CTX and PD created outside the PMD.
> +It gets as devargs the device's ``cmd_fd`` and ``pd_handle``,
> +then using those arguments to import objects.
> +See :ref:`mlx5 driver options <mlx5_common_driver_options>` for more information.
> +
> +When ``cmd_fd`` and ``pd_handle`` arguments are coming from another process,
> +the FD must be dup'd before being passed.
> +In this function, testpmd initializes IPC socket to get FD using SCM_RIGHTS.
> +It gets the external process socket path, then import the ``cmd_fd`` and
> +``pd_handle`` arguments and add them to devargs list.
> +After updating this, it calls the regular ``port attach`` function
> +with extended idevtifier.
> +
> +For example, to attach a port whose pci address is ``0000:0a:00.0`` and its
> +socket path is ``/var/run/import_ipc_socket``.
> +
> +.. code-block:: console
> +
> +   testpmd> port attach 0000:0a:00.0 mlx5_socket=/var/run/import_ipc_socket
> +   Attaching a new port...
> +   testpmd: MLX5 socket path is /var/run/import_ipc_socket
> +   testpmd: Attach port with extra devargs 0000:0a:00.0,cmd_fd=40,pd_handle=1
> +   EAL: Probe PCI driver: mlx5_pci (15b3:101d) device: 0000:03:00.0 (socket 0)
> +   Port 0 is attached. Now total ports is 1
> +   Done
> +
> +


Hi Michael,

This is too much mlx5 specific addition, and I don't think it is
good to extend testpmd with PMD specific code.
If we enable it, sure there will be other vendors willing to do
the same, making testpmd even messier.

I don't know what those ``cmd_fd`` and ``pd_handle`` (that read
from provided socket), but can they be read from some other
script and feed to testpmd, like a python wrapper etc...