From d07439d5fdbcec497dc251c5c4e77d1660cd195b Mon Sep 17 00:00:00 2001
From: akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 23 May 2013 13:49:10 +0000
Subject: [PATCH] Add a comment.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40901 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ext/dbm/extconf.rb | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/ext/dbm/extconf.rb b/ext/dbm/extconf.rb
index 32a944634a..5a04881616 100644
--- a/ext/dbm/extconf.rb
+++ b/ext/dbm/extconf.rb
@@ -1,3 +1,19 @@
+# configure option:
+#   --with-dbm-type=COMMA-SEPARATED-NDBM-TYPES
+#
+# ndbm type:
+#   libc        ndbm compatible library in libc.
+#   db          Berkeley DB (libdb)
+#   db2         Berkeley DB (libdb2)
+#   db1         Berkeley DB (libdb1)
+#   db5         Berkeley DB (libdb5)
+#   db4         Berkeley DB (libdb4)
+#   db3         Berkeley DB (libdb3)
+#   gdbm_compat GDBM since 1.8.1 (libgdbm_compat)
+#   gdbm        GDBM until 1.8.0 (libgdbm)
+#   qdbm        QDBM (libqdbm)
+#   ndbm        Some legacy OS may have libndbm.
+
 require 'mkmf'
 
 dir_config("dbm")