Add comments

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@749 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 13 insertions, 0 deletions

diff --git a/srcdir.mk b/srcdir.mk
index 6a21d9db..484bb420 100644
--- a/srcdir.mk
+++ b/srcdir.mk
@@ -1 +1,14 @@
+# This is the version of srcdir.mk that gets used when you build in
+# the source tree.  In contrast, when you build in a separate build tree,
+# you use a version of srcdir.mk that Configure created, which sets SRCDIR
+# to the location of the source tree.
+
+# This is designed to be included by the top level make file, with
+# SRCDIR being passed to all the submakes.  That means that when you
+# build in a separate build tree, you must build from the top; you
+# can't go into a subdirectory and type "make".  When you build in the
+# _source_ tree, local makes work because every local make file checks
+# whether SRCDIR is set, and if it isn't, sets it with the assumption
+# that the build directory and source directory are the same.
+
 SRCDIR = $(CURDIR)