--- /dev/null
+# -----------------------------------------------------------------------------
+#
+# (c) 2010 The University of Glasgow
+#
+# This file is part of the GHC build system.
+#
+# To understand how the build system works and how to modify it, see
+# http://hackage.haskell.org/trac/ghc/wiki/Building/Architecture
+# http://hackage.haskell.org/trac/ghc/wiki/Building/Modifying
+#
+# -----------------------------------------------------------------------------
+
+define extra-packages
+$$(foreach p,$$(patsubst libraries/%,%,$$(wildcard $$(shell grep '^[^ ]\+ \+\(dph\|extra\) \+[^ ]\+ \+[^ ]\+ \+[^ ]\+' packages | sed 's/ .*//'))),\
+ $$(eval BUILD_DIRS += libraries/$$p)\
+ $$(if $$(wildcard libraries/$$p/ghc-packages),\
+ $$(foreach q,$$(shell cat libraries/$$p/ghc-packages2),$$(eval $$(call extra-package,$$p,$$p/$$q))),\
+ $$(eval $$(call extra-package,$$p,$$p)))\
+)
+endef
+
+define extra-package # $1 = package root, $2 = package
+ifeq "$(wildcard libraries/$1/ghc-stage2-package)" ""
+$$(eval $$(call addPackage,$2))
+else
+$$(eval $$(call addPackage2,$2))
+endif
+endef
+