[PATCH v8] doc: add PMD known issue

[Stephen Hemminger]

On Sat, 28 Jan 2023 06:01:38 +0000
Mingjin Ye <mingjinx.ye at intel.com> wrote:

> Add a known issue: Rx path dynamic change is not supported for PMD.
> 
> Fixes: de853a3bb151 ("net/ice: disable DDP package on Windows")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Mingjin Ye <mingjinx.ye at intel.com>
> ---
>  doc/guides/nics/ice.rst | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/doc/guides/nics/ice.rst b/doc/guides/nics/ice.rst
> index ce075e067c..115625523e 100644
> --- a/doc/guides/nics/ice.rst
> +++ b/doc/guides/nics/ice.rst
> @@ -395,3 +395,15 @@ file is used by both the kernel driver and the DPDK PMD.
>  
>        Windows support: The DDP package is not supported on Windows so,
>        loading of the package is disabled on Windows.
> +
> +ice: Rx path does not support dynamic change
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +The ice driver supports fast and offload rx path. When pmd is initialized,
> +the fast rx path is selected by default. Even if offload is subsequently
> +enabled through the API, which will not work because the past rx path is
> +still used.
> +
> +The ice driver does not support to change the rx path after application
> +is initialized. If HW offload is required, the ``--rx-offloads`` parameter
> +should be used to choose the offload Rx path by default.

Is this when the device is stopped, or running.
Dynamic configuration of offload parameters is not safe on many devices.
Usually the device driver requires the device not be started to change offloads.

The driver should reject in the API things it does not support.