datapath: Add a find the kernel source directory for Debian 2.6.32+.

Debian's kernel-headers packages starting from 2.6.32 (or thereabouts) put
links to the kernel build and source directories at the same level, named
"build" and "source" respectively.  Add support for this structure.

diff --git a/acinclude.m4 b/acinclude.m4
index 490936e..d33a7c4 100644 (file)
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1,6 +1,6 @@
 # -*- autoconf -*-
 
-# Copyright (c) 2008, 2009 Nicira Networks.
+# Copyright (c) 2008, 2009, 2010 Nicira Networks.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -42,7 +42,14 @@ AC_DEFUN([OVS_CHECK_LINUX26], [
     AC_MSG_CHECKING([for Linux 2.6 source directory])
     KSRC26=$KBUILD26
     if test ! -e $KSRC26/include/linux/kernel.h; then
-      KSRC26=`(cd $KBUILD26 && pwd -P) | sed 's,-[[^-]]*$,-common,'`
+      case `echo "$KBUILD26" | sed 's,/*$,,'` in # (
+        */build)
+          KSRC26=`echo "$KBUILD26" | sed 's,/build/*$,/source,'`
+          ;; # (
+        *)
+          KSRC26=`(cd $KBUILD26 && pwd -P) | sed 's,-[[^-]]*$,-common,'`
+          ;;
+      esac
       if test ! -e $KSRC26/include/linux/kernel.h; then
         AC_MSG_ERROR([cannot find source directory])
       fi