travis: add a bunch of comments explaining things

.travis.yml

@@ -1,14 +1,27 @@
+# Use "required" for sudo, because we want to use the "trusty" Debian
+# distro, which is (currently) only available in the legacy Travis
+# infrastructure (i.e., if we put "sudo: false" to use the new container-
+# based Travis infrastructure, then "trusty" is not available).  We
+# need the "trusty" distro because it has more recent versions of the
+# GNU Autotools (i.e., autogen.pl will fail if you use the regular
+# distro because the GNU Autotools are too old).
 sudo: required
 dist: trusty
 language: c
+
+# Iterate over 2 different compilers
 compiler:
     - gcc
     - clang
+
+# Iterate over 2 different OSs
 os:
     - linux
     - osx
 
 addons:
+    # For Linux, make sure we have some extra packages that we like to
+    # build with
     apt:
         packages:
             - autoconf
@@ -37,6 +50,9 @@ before_install:
     - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then git clone https://github.com/ofiwg/libfabric.git ; fi
     - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then cd libfabric && ./autogen.sh && ./configure --prefix=$HOME/bogus --enable-usnic --disable-verbs && make install && cd .. ; fi
 
+# Note that we use "make -k" to do the entire build, even if there was a
+# build error in there somewhere.  This prevents us from needing to submit
+# to Travis, see the first error, fix that first error, submit again, ...etc.
 install:
     - m4 --version
     - autoconf --version
@@ -46,5 +62,7 @@ install:
     - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CC" == "gcc" ]]; then ./configure $CONFIGURE_ARGS --with-libfabric=$HOME/bogus --with-usnic --with-verbs; else ./configure $CONFIGURE_ARGS; fi
     - make -k
 
+# We only need to distcheck on one OS / compiler combination (this is just
+# a minor optimization to make the overall set of builds faster).
 script:
     - if [[ "$TRAVIS_OS_NAME" == "linux" && "$CC" == "gcc" ]]; then make distcheck; else make check; fi