On Wed, 5 Aug 2020 14:40:01 +0530 Jerin Jacob <jerinjac...@gmail.com> wrote:
> On Wed, Aug 5, 2020 at 2:16 PM Kinsella, Ray <m...@ashroe.eu> wrote: > > > > > > > > On 04/08/2020 17:20, Stephen Hemminger wrote: > > > On Tue, 4 Aug 2020 11:41:53 +0100 > > > Bruce Richardson <bruce.richard...@intel.com> wrote: > > > > > >> On Mon, Aug 03, 2020 at 12:59:03PM +0530, pbhagavat...@marvell.com > > >> wrote: > > >>> From: Pavan Nikhilesh <pbhagavat...@marvell.com> > > >>> > > >>> Add 64 byte padding at the end of event device public structure to allow > > >>> future extensions. > > >>> > > >>> Signed-off-by: Pavan Nikhilesh <pbhagavat...@marvell.com> > > >>> Acked-by: Jerin Jacob <jer...@marvell.com> > > >>> --- > > >>> v2 Changes: > > >>> - Modify commit title. > > >>> - Add patch reference to doc. > > >>> > > >>> doc/guides/rel_notes/deprecation.rst | 11 +++++++++++ > > >>> 1 file changed, 11 insertions(+) > > >>> > > >>> diff --git a/doc/guides/rel_notes/deprecation.rst > > >>> b/doc/guides/rel_notes/deprecation.rst > > >>> index ea4cfa7a4..ec5db68e9 100644 > > >>> --- a/doc/guides/rel_notes/deprecation.rst > > >>> +++ b/doc/guides/rel_notes/deprecation.rst > > >>> @@ -151,3 +151,14 @@ Deprecation Notices > > >>> Python 2 support will be completely removed in 20.11. > > >>> In 20.08, explicit deprecation warnings will be displayed when > > >>> running > > >>> scripts with Python 2. > > >>> + > > >>> +* eventdev: A 64 byte padding is added at the end of the following > > >>> structures > > >>> + in event device library to support future extensions: > > >>> + ``rte_event_crypto_adapter_conf``, ``rte_event_eth_rx_adapter_conf``, > > >>> + ``rte_event_eth_rx_adapter_queue_conf``, > > >>> ``rte_event_eth_tx_adapter_conf``, > > >>> + ``rte_event_timer_adapter_conf``, ``rte_event_timer_adapter_info``, > > >>> + ``rte_event_dev_info``, ``rte_event_dev_config``, > > >>> ``rte_event_queue_conf``, > > >>> + ``rte_event_port_conf``, ``rte_event_timer_adapter``, > > >>> + ``rte_event_timer_adapter_data``. > > >>> + Reference: > > >>> + > > >>> http://patches.dpdk.org/project/dpdk/list/?series=10728&archive=both&state=* > > >>> -- > > >> > > >> I don't like this idea of adding lots of padding to the ends of these > > >> structures. For some structures, such as the public arrays for devices it > > >> may be necessary, but for all the conf structures passed as parameters to > > >> functions I think we can do better. Since these structures are passed by > > >> the user to various functions, function versioning can be used to ensure > > >> that the correct function in eventdev is always called. From there to the > > >> individual PMDs, we can implement ABI compatibility by either: > > >> 1. including the length of the struct as a parameter to the driver. > > >> (This is > > >> a bit similar to my proposal for rawdev [1]) > > >> 2. including the ABI version as a parameter to the driver. > > >> > > >> Regards > > >> /Bruce > > >> > > >> [1] http://inbox.dpdk.org/dev/?q=enhance+rawdev+APIs > > > > > > This is a bad idea. > > > > > > Reserved fields won't work because nothing requires that the application > > > zero them. You can't start using them later because the application > > > may put uninitialized or junk data there. > > > > > > > +1, to Stephens comments. > > Since the problem is not specific to one substem, if we need to add a > field in config structures, > What will the expected way of handling across the DPDK? If you need fields go through the normal enhancement process, and get it reviewed and put them in a major release milestone. Sorry, there is no free lunch by adding reserved fields. Look up YAGNI
