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 490936e1de2a0556706511d4cf5af6541ef99386..d33a7c45a689df02d0c55e094732ef72020963e6 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