+#
+# The source package should be downloaded and compiled only once.
+# If the working directory is cleared, the cached version will be lost.
+# On test servers, which clear the working directory frequently,
+# it may be a good idea to use a local version of the source packages.
+# To do so, download the following two packages and put them in your HOME directory.
+# * http://www.hboehm.info/gc/gc_source/gc-7.4.0.tar.gz
+# * http://www.hboehm.info/gc/gc_source/libatomic_ops-7.4.0.tar.gz