10/11/2020 15:34, Bruce Richardson: > On Tue, Nov 10, 2020 at 02:37:02PM +0100, Thomas Monjalon wrote: > > 10/11/2020 12:19, Bruce Richardson: > > > On Tue, Nov 10, 2020 at 09:17:36AM +0100, David Marchand wrote: > > > > On Tue, Nov 10, 2020 at 4:02 AM Jiang, Cheng1 <cheng1.ji...@intel.com> > > > > wrote: > > > > > > - This series breaks external compilation, as the external Makefile > > > > > > was not > > > > > > updated. > > > > > > > > > > > > > > > > I'm not sure I understand what you mean by external Makefile, > > > > > because as far as I know, makefile has been deprecated. > > > > > > > > make support is dropped for dpdk compilation itself. > > > > > > > > For the examples, the users will use make to compile them, as this is > > > > the only way provided to users *out of* dpdk. > > > > But the examples are compiled too via meson when compiling dpdk itself > > > > if you pass -Dexamples= options. > > > > > > > > > > > > Bruce, > > > > > > > > I want to avoid more misses like this one. > > > > > > > > If we want to keep the examples compilation in meson, we need a > > > > consistent framework to compile in both cases. > > > > Right now, we don't export meson for examples, and it makes no sense > > > > in their current form. > > > > It seems simpler to me to only maintain make support, and meson can > > > > still call make for each example. > > > > > > > > Another solution is to rely only on test-meson-builds.sh, but then it > > > > ends up on the maintainer shoulders, so I prefer the solution above. > > > > > > > > Other ideas? > > > > > > > > > > Hi David, > > > > > > I've been thinking a bit about this since I got your email, but > > > inspiration > > > for new ideas has yet to strike me. > > > > > > While I can see the downside of having both make and meson build files for > > > the examples, I'm loath to see one of them dropped. Here is my current > > > thinking on it: > > > > > > * We obviously need to keep the basic makefiles so as to make it easy for > > > end-users to compile up and use the examples separate from DPDK itself. > > > The makefiles serve as good examples as to how to pull the DPDK info > > > from > > > pkg-config. > > > > The external compilation is part of the example, yes. > > > > > * On the other hand, being able to build the examples as part of a regular > > > meson build is a big advantage over having to build them separately, and > > > allows errors with examples to be caught quicker. > > > > In the past we had a Makefile which builds all examples. > > If you want, it can even been called at the end of meson DPDK compilation. > > > > Yes, we can do that, but my concern is not so much about having them built > as part of build tests, but rather having them part of a build workflow for > developers during development. Thinking here in particular of those coding > with IDEs such as eclipse or VScode, which I know a lot of people use - > including myself from time to time, depending on what I am working on. > > > > It's also useful for those of us working on specific components > > > with associated sample apps to have just that one app built constantly > > > as we work. > > > > I don't understand this point: > > ninja -C build && make -C examples/myexample > > > > That works fine for building on the commandline, but does not work well for > building as part of "build-on-save" inside an IDE, which is the biggest > reason I want to keep support for building examples using meson. For doing > development with a feature and associated sample app, being able to > configure your build folder to rebuild a particular sample app as part of a > main infrastructure rebuild is really useful - and works really quickly > too, since incremental builds of C file changes happen really fast with > meson. > > > > * Therefore, while it looks like the more logical part to drop is indeed > > > the meson support for the examples, > > > > Yes, building the examples from the inside build system is strange, > > and hide issues. > > > > Sorry, while it may hide issues with the makefile because people weren't > really aware that they were sticking around, it definitely helps pick up > issues with C code changes as you are developing. > > > > we may struggle to implement clean > > > building of the examples from meson using make, at least until meson > > > 0.54 > > > becomes our standard. Before that version, we don't have a > > > "meson-uninstalled" folder with build-time package-config file to use as > > > source of build flags for each example. > > > > We don't have to use meson at all. > > > > No, we don't, so long as we don't miss out on the benefits we currently get > from having it integrated. > > > > * One final idea I had and investigated in the past was whether we could > > > at > > > build or install time auto-generate the Makefile for each example from > > > the meson.build file. Unfortunately, nothing came of that idea the first > > > time I tried it, but it might still be worth looking at. Even if it > > > works > > > for 80-90% of cases, it means that we have a much smaller subset of > > > examples where we need to test independently the make and meson builds. > > > > Hand-crafted Makefile is enough. They may be improved. > > If we feel it is too hard, we can use another build system > > in examples, like cmake. > > > > > So overall my assessment is that it needs a bit of investigation and > > > prototyping to see what we can come up with. > > > > I think testing external build + removing build from internal meson > > would be a good start to ensure quality of examples maintenance. > > > If we remove the meson build of the examples, I think we need equivalent > functionality provided some other way. Calling make for examples from > within meson may be good enough, so long as it's not too slow. > > > > On a semi-related note, it's perhaps a bigger problem that we cannot rely > > > on test-meson-builds and CI infrastructure to prevent issues like this. > > > > We can. We just have to add all examples in test-meson-builds.sh. > > > > Yep, definite +1 here. > Once that is done, I'd then like to wait and see what future issues crop up > before we start ripping out other bits. This is the first release where we > have removed the make build system, so there are lots of teething issues > all over the place, of which this is but one example! > > > > Surely this is what CI is there for - to help reduce the workload for > > > maintainers. The fact that we are considering removing the meson build of > > > examples because we cannot rely on CI is surely more worthy of a solution > > > than trying to find a way to build examples with make from within meson? > > > > No the concern is to have all contributors work on the same > > single build path. > > > Building all examples from test-meson-build should probably be sufficient > here, I think. > > > > Perhaps we need to see about stricter measures from CI failure, e.g. > > > anything failing travis build automatically gets marked as changes > > > requested in patchwork, and the author gets an email informing them of > > > such? > > > > When there is a failure, authors receive an email, > > and maintainers can see a red flag. I think it's OK. > > > > The only issue was that this build path was not tested. > > I think David is going to fix it by compiling all possible examples > > with external make build from test-meson-builds.sh. > > > > Seems like we are all aligned on the first step anyway. Let's see beyond > that what needs to be done in 21.02.
OK
