[PATCH rtems-docs v2] zynqmp: Add commentary about lwIP usage

[Chris Johns]

This is much clearer. I now understand the limitation.

OK to push.

Thanks
Chris

On 20/7/2022 11:34 pm, Kinsey Moore wrote:
> ---
>  user/bsps/aarch64/xilinx-zynqmp.rst | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/user/bsps/aarch64/xilinx-zynqmp.rst b/user/bsps/aarch64/xilinx-zynqmp.rst
> index 78bff12..239ebe4 100644
> --- a/user/bsps/aarch64/xilinx-zynqmp.rst
> +++ b/user/bsps/aarch64/xilinx-zynqmp.rst
> @@ -244,6 +244,18 @@ Cadence GEM instances present on all ZynqMP hardware variants. All interfaces
>  are enabled by default, but only interfaces with operational MII busses will be
>  recognized and usable in RTEMS. Most ZynqMP dev boards use CGEM3.
>  
> +When used with lwIP from the rtems-lwip integration repository, these BSP
> +variants support networking via CGEM0 and one of the other CGEM* instances
> +simultaneously. This is a limitation of the Xilinx driver, specifically
> +in code referring directly to XPAR_XEMACPS_0_BASEADDR. Attempting to use more
> +than two interfaces simultaneously may cause unexpected behavior. Attempting to
> +use a set of two interfaces that does not include CGEM0 may cause unexpected
> +behavior.
> +
> +The interfaces will not come up by default under lwIP and must be configured
> +manually. There are examples of this in the start_networking() implementation
> +in netstart.c as used by the network tests.
> +
>  Running Executables on QEMU
>  ---------------------------
>