[ovs-dev] [PATCH] faq: Better document how to add vendor extensions.

[Yi-Hung Wei]

On Mon, Oct 9, 2017 at 10:33 AM, Ben Pfaff <blp at ovn.org> wrote:
> Signed-off-by: Ben Pfaff <blp at ovn.org>
> ---
>  Documentation/faq/contributing.rst | 44 +++++++++++++++++++++++++++-----------
>  include/openvswitch/ofp-errors.h   |  4 +++-
>  2 files changed, 34 insertions(+), 14 deletions(-)
>
> diff --git a/Documentation/faq/contributing.rst b/Documentation/faq/contributing.rst
> index 6dfc8bc4d436..d59376cd615c 100644
> --- a/Documentation/faq/contributing.rst
> +++ b/Documentation/faq/contributing.rst
> @@ -33,22 +33,28 @@ Q: How do I implement a new OpenFlow message?
>      as needed.  (If you configure with ``--enable-Werror``, as described in
>      :doc:`/intro/install/general`, then it is impossible to miss any warnings.)
>
> -    If you need to add an OpenFlow vendor extension message for a vendor that
> -    doesn't yet have any extension messages, then you will also need to edit
> -    ``build-aux/extract-ofp-msgs``.
> +    To add an OpenFlow vendor extension message (aka experimenter message) for
> +    a vendor that doesn't yet have any extension messages, you will also need
> +    to edit ``build-aux/extract-ofp-msgs`` and at least ``ofphdrs_decode()``
> +    and ``ofpraw_put__()`` in ``lib/ofp-msgs.c``.  OpenFlow doesn't standardize
> +    vendor extensions very well, so it's hard to make the process simpler than
> +    that.  (If you have a choice of how to design your vendor extension
> +    messages, it will be easier if you make them resemble the ONF and OVS
> +    extension messages.)
>
>  Q: How do I add support for a new field or header?
>
>      A: Add new members for your field to ``struct flow`` in ``lib/flow.h``, and
>      add new enumerations for your new field to ``enum mf_field_id`` in
> -    ``lib/meta-flow.h``, following the existing pattern.  Also, add support to
Instead of ``lib/meta-flow.h``, maybe
``include/openvswitch/meta-flow.h``? Otherwise, looks good to me.

Acked-by: Yi-Hung Wei <yihung.wei at gmail.com>