When I was working on "wip-openssl", I quickly found myself bogged down dealing with build issues. 1. why I do out of tree builds 2. changes for out of tree builds 3. doing an out of tree build 4. well, not quite ____ 1. why I do out of tree builds So, as a matter of habit, I do most of my large project builds doing "out of tree" builds. There are a variety of reasons I have adopted this habit. For many years, I was supporting multiple architectures in a shared filesystem, and it was a lot easier to not lose changes if I had one source tree shared between several build trees. (especially when my source control system was rcs!) Today, I still like to do this; it means I can more easily test out several different configurations in parallel, efficiently put an old build aside for later reference, and quickly discard older stuff without fear of losing an important source change. And so, with wip-openssl, I find myself with several different build configurations: with cmake, and with automake. Cmake is my preferred solution: it works faster, and excepting for one recent change it supports out of tree builds just fine. [ the one exception is rocksdb, and I'll post separately on that. ] For automake, I found myself looking at a much longer list of things that didn't quite work. ____ 2. changes for out of tree builds List of commits from wip-openssl that together do most of what I want, 96f16f9c61b8f96ddb86c3b3630078c4a28058ec 0a60a5fa3582a97a2a8914dc96abe469f3244fbe WITH_DLIBROCKSDB I'm used to other automake based systems where one can say things like "with-krb5=yes" and have it find the external (system) copy of krb5. I am not sure "with-rocksdb" ever really worked right in ceph, but it kind of looked like it wanted a dynamic version of rocksdb (again, I'll post more on that separately.) So I wound up repurposing this to mean just that. ddca62ffdb3b7908140f7c4072692b6148bd54a0 src/ceph.in is a classic sort of "out of tree" build problem. The proper automake way to reference src/ceph.in is $(srcdir)/ceph.in . With gnu make, it's possible to cheat and just call it $< . Do we support other makes? e51fd743587454cf0b08aaea4977eee253a71664 build version files are another ubiquitious "out of tree" build problem. In ceph, the use of "FORCE" for this logic means every make run wants to relink every library and executable, which really slows things down. I left .git_version in the source tree but moved ceph_ver.h to the object tree. This doesn't make me completely happy, but it at least gave me something buildable. 1ddd0ed672d1a8a8201b1bf65cf6a173456320c6 c8792d96e5c2cfbdaf555e9ae545cb2aa0d7c8e6 pybind/setup.py wanted to read ceph_ver.h. I should probably have taught it to read ceph_ver.h in the build tree, but instead I taught it to find .git_version. I did put logic in it to construct "PEP-440" friendly version tags, which got rid of one build warning. ____ 3. doing an out of tree build With this set of changes, I can now make a "readonly" source tree and build with it this way, git clone -b wip-openssl git@xxxxxxxxxx:ceph/ceph.git ceph-ssl cd ceph-ssl git clean -fdx git submodule update --init --recursive sh autogen.sh sleep 1; touch src/acconfig.h.in src/gmock/build-aux/config.h.in rm -f src/.git_version src/ceph_ver.h src/make_version -g src/.git_version find . \! -type l -print0 | xargs -0 chmod a-w mkdir ../td ; cd ../td CFLAGS="-fno-omit-frame-pointer -g -O2" CXXFLAGS="-fno-omit-frame-pointer -g" \ ../ceph-ssl/configure --with-debug --with-radosgw \ --with-libatomic-ops --without-lttng --disable-static \ --with-librocksdb=yes --with-librocksdb-static=no The "sleep 1" business is because it turns out that src/acconfig.h.in src/gmock/build-aux/config.h.in have to be at least 1 second newer than other stuff in the source tree, and my build machine is fast enough at running autogen.sh that that's never true. I think autogen.sh could also be making .git_version directly, but I didn't bother here. ____ 4. well, not quite This will still blow up late in the build process. There's something that makes 2 python virtual environments in the source tree. They should be in the build tree, and also this should be part of "make check", not "make all". But other than that, I have something that works, and that doesn't blow up git builder. -Marcus Watts -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
