diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index 60fa1a8922..5015002aac 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -935,7 +935,7 @@ include $(PGXS)
To use the PGXS infrastructure for your extension,
you must write a simple makefile.
In the makefile, you need to set some variables
- and finally include the global PGXS makefile.
+ and include the global PGXS makefile.
Here is an example that builds an extension module named
isbn_issn, consisting of a shared library containing
some C code, an extension control file, a SQL script, and a documentation
@@ -1171,6 +1171,33 @@ include $(PGXS)
+
+ You can also run make in a directory outside the source
+ tree of your extension, if you want to keep the build directory separate.
+ This procedure is also called a
+ VPATHVPATH
+ build. Here's how:
+
+ mkdir build_dir
+ cd build_dir
+ make -f /path/to/extension/source/tree/Makefile
+ make -f /path/to/extension/source/tree/Makefile install
+
+
+
+
+ Alternatively, you can set up a directory for a VPATH build in a similar
+ way to how it is done for the core code. One way to to this is using the
+ core script config/prep_buildtree>. Once this has been done
+ you can build by setting the make variable
+ USE_VPATH like this:
+
+ make USE_VPATH=/path/to/extension/source/tree
+ make USE_VPATH=/path/to/extension/source/tree install
+
+ This procedure can work with a greater variety of directory layouts.
+
+
The scripts listed in the REGRESS> variable are used for
regression testing of your module, which can be invoked by make