On 6/5/15, 5:47 AM, "Bruce Richardson" <bruce.richardson at intel.com> wrote:
>On Fri, Jun 05, 2015 at 11:25:09AM +0000, Wang, Liang-min wrote: >> >> >> > -----Original Message----- >> > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] >> > Sent: Friday, June 05, 2015 6:47 AM >> > To: Andrew Harvey (agh) >> > Cc: Stephen Hemminger; Wang, Liang-min; dev at dpdk.org >> > Subject: Re: [dpdk-dev] [PATCH 2/2] ethtool: add new library to >>provide >> > ethtool-alike APIs >> > >> > 2015-06-04 22:10, Andrew Harvey: >> > > On 6/4/15, 7:58 AM, "Stephen Hemminger" >> > <stephen at networkplumber.org> wrote: >> > > >"Andrew Harvey (agh)" <agh at cisco.com> wrote: >> > > >> I believe that their is value in this interface for software >>stacks >> > > >>not based on Linux being moved toward DPDK that need simple >> > > >>operations like getting the mac address. Some of these stacks >>have >> > > >>a dearth of resources available and dedicating a core/thread to >>KNI >> > > >>to get/set a mac address is considered excessive. There are also >> > > >>issues with 32/64 bit kernel integration using KNI. If the >> > > >>ethtool interface is not the correct interface then please help >>me >> > > >>understand what should/could have been used. If ethtool is >> > > >>considered 'old and clunky? Stephen's and your input would be >> > > >>valuable in designing another interface with similar properties. >> > > >>The use-case is pretty simple and there is no plans for moving >> > > >>anything back into the kernel on the contrary its the complete >>opposite. >> > > >> >> > > >> ? Andy >> > > > >> > > >We have DPDK API's to do this, and any added wrappers make it >>bigger. >> > > >I don't see why calling your ethtool API is better than calling >> > > >rte_eth* API. >> > > > >> > > >If there is a missing functionality in the rte_ethXXX api's for an >> > > >application then add that. For example: rte_eth_mac_addr_get() >> > > >> > > I am getting somewhat confused by your latest comments. Your first >> > > email (referenced below) looked really positive and I found your >> > > suggestions useful. Your latest post appears to contradict this and >> > > now the interface was there all the time. The wrapper fa?ade >>provided >> > > by the ethtool library provide a clean separation of concerns and >>will >> > > allow people to migrate from not only KNI but in our case from a >> > > legacy system. If a software stack has requirements to work with >> > > multiple IO abstractions then the ethtool approach is attractive. I >> > > would speculate that many other stacks moving towards dpdk will have >> > similar issues. >> > > >> > > Summarizing, for our use-cases the ethtool interface facilitated our >> > > adoption to dpdk while allowing us to support our legacy IO >>abstractions. >> > >> > Stephen and me say the same thing about using the ethdev API. >> > We don't understand why using a fake ethtool lib would be easier. >> > Though you are saying it "facilitated [your] adoption to dpdk". >> > Please could you explain why using an ethtool-like API is easier than >>using >> > the existing ethdev API? >> > In any case, you have to develop a specific backend for DPDK >>(rte_ethtool >> > would be also DPDK-specific). >> >> As described earlier in this patch comment reply, there are other >>ethtool ops that have been implemented. >> Those ops includes set/get eeprom, set/get pauseparam, set/get >>ringparam which are not available in the exiting ethdev library. >> For this release, we focus on releasing some basic functions (btw, >>mac_addr_set is not available but is covered by this patch). >> The key reason that this set of library is not released as part of >>ethdev is the ethtool API dependency on kernel include file. >> To faithfully carry the ethtool ops and net dev ops API parameters, the >>ethtool APIs are designed to follow the original definition except >>avoiding carry kernel states. >> With that, to support ethtool APIs faithfully, we need to include >><linux/ethtool.h>. >> As suggested by many DPDK veterans including Thomas (indicated over >>your reply), you would prefer these APIs in a separate library. >> >> > >> > It seems you already started to use such an ethtool implementation. >> > Please note that our goal is not to prevent Cisco from upstreaming >>(evidence >> > with enic driver integration) but we want to guide you, and others >>having the >> > same needs, to the best solution for everybody. >> > That's why we need to understand what we (or you) are missing. >> > Maybe that it would be clearer with some code examples (which would >>go in >> > the lib documentation if any). >> > >> > Thanks > >How about doing this work as a sample application initially, to >demonstrate how >an application written using ethtool APIs could be shimmed to use DPDK >underneath. >The ethtool to dpdk mapping could be contained in a single header file >(or header >and c file) inside the sample app. This would allow easy re-use of the >shim >layer, while at the same time not making it part of the core DPDK >libraries. > >Regards, >/Bruce This would appear to be the most pragmatic way forward. It would allow others to see more of the code and judge its value for themselves. I have no issues with this approach if others agree. ? Andy