On Mon, Jan 30, 2023 at 3:26 PM Naga Harish K, S V <[email protected]> wrote: > > > > > -----Original Message----- > > From: Jerin Jacob <[email protected]> > > Sent: Saturday, January 28, 2023 4:24 PM > > To: Naga Harish K, S V <[email protected]> > > Cc: [email protected]; Carrillo, Erik G <[email protected]>; > > Gujjar, > > Abhinandan S <[email protected]>; [email protected]; > > Jayatheerthan, Jay <[email protected]> > > Subject: Re: [PATCH v2 1/3] eventdev/eth_rx: add params set/get APIs > > > > On Wed, Jan 25, 2023 at 10:02 PM Naga Harish K, S V > > <[email protected]> wrote: > > > > > > > > > > > > > -----Original Message----- > > > > From: Jerin Jacob <[email protected]> > > > > > > > > > > > > > > > > > > + */ > > > > > > > > > + uint32_t rsvd[15]; > > > > > > > > > + /**< Reserved fields for future use */ > > > > > > > > > > > > > > > > Introduce rte_event_eth_rx_adapter_runtime_params_init() to > > > > make > > > > > > > > sure rsvd is zero. > > > > > > > > > > > > > > > > > > > > > > The reserved fields are not used by the adapter or application. > > > > > > > Not sure Is it necessary to Introduce a new API to clear reserved > > fields. > > > > > > > > > > > > When adapter starts using new fileds(when we add new fieds in > > > > > > future), the old applicaiton which is not using > > > > > > rte_event_eth_rx_adapter_runtime_params_init() may have junk > > > > > > value and then adapter implementation will behave bad. > > > > > > > > > > > > > > > > > > > > > > does it mean, the application doesn't re-compile for the new DPDK? > > > > > > > > Yes. No need recompile if ABI not breaking. > > > > > > > > > When some of the reserved fields are used in the future, the > > > > > application > > > > also may need to be recompiled along with DPDK right? > > > > > As the application also may need to use the newly consumed > > > > > reserved > > > > fields? > > > > > > > > The problematic case is: > > > > > > > > Adapter implementation of 23.07(Assuming there is change params) > > > > field needs to work with application of 23.03. > > > > rte_event_eth_rx_adapter_runtime_params_init() will sove that. > > > > > > > > > > As rte_event_eth_rx_adapter_runtime_params_init() initializes only > > reserved fields to zero, it may not solve the issue in this case. > > > > rte_event_eth_rx_adapter_runtime_params_init() needs to zero all fields, > > not just reserved field. > > The application calling sequence is > > > > struct my_config c; > > rte_event_eth_rx_adapter_runtime_params_init(&c) > > c.interseted_filed_to_be_updated = val; > > > Can it be done like > struct my_config c = {0}; > c.interseted_filed_to_be_updated = val; > and update Doxygen comments to recommend above usage to reset all fields? > This way, rte_event_eth_rx_adapter_runtime_params_init() can be avoided.
Better to have a function for documentation clarity. Similar scheme already there in DPDK. See rte_eth_cman_config_init() > > > Let me share an example and you can tell where is the issue > > > > 1)Assume parameter structure is 64B and for 22.03 8B are used. > > 2)rte_event_eth_rx_adapter_runtime_params_init() will clear all 64B. > > 3)There is an application written based on 22.03 which using only 8B after > > calling rte_event_eth_rx_adapter_runtime_params_init() > > 4)Assume, in 22.07 another 8B added to structure. > > 5)Now, the application (3) needs to run on 22.07. Since the application is > > calling rte_event_eth_rx_adapter_runtime_params_init() > > and 9 to 15B are zero, the implementation will not go bad. > > > > > The old application only tries to set/get previous valid fields and the > > > newly > > used fields may still contain junk value. > > > If the application wants to make use of any the newly used params, the > > application changes are required anyway. > > > > Yes. If application wants to make use of newly added features. No need to > > change if new features are not needed for old application.
