From 22ccfaa8b5f6a6e8a770667a9d412828906a4332 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Thu, 10 Feb 2011 14:40:57 -0800
Subject: [PATCH] Prefer /lib/modules/$(uname -r)/ links

Preferentially use the /lib/modules/$(uname -r)/source and
/lib/modules/$(uname -r)/build links.  Only if neither of these
links exist fallback to alternate methods for deducing which
kernel to build with.  This resolves the need to manually
specify --with-linux= and --with-linux-obj= on Debian systems.
---
 config/spl-build.m4 | 11 ++++++++---
 configure           | 22 ++++++++++++++++------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/config/spl-build.m4 b/config/spl-build.m4
index c18db70df..d8eadb7e9 100644
--- a/config/spl-build.m4
+++ b/config/spl-build.m4
@@ -105,8 +105,11 @@ AC_DEFUN([SPL_AC_KERNEL], [
 
 	AC_MSG_CHECKING([kernel source directory])
 	if test -z "$kernelsrc"; then
-		headersdir="/lib/modules/$(uname -r)/build"
-		if test -e "$headersdir"; then
+		if test -e "/lib/modules/$(uname -r)/source"; then
+			headersdir="/lib/modules/$(uname -r)/source"
+			sourcelink=$(readlink -f "$headersdir")
+		elif test -e "/lib/modules/$(uname -r)/build"; then
+			headersdir="/lib/modules/$(uname -r)/build"
 			sourcelink=$(readlink -f "$headersdir")
 		else
 			sourcelink=$(ls -1d /usr/src/kernels/* \
@@ -132,7 +135,9 @@ AC_DEFUN([SPL_AC_KERNEL], [
 	AC_MSG_RESULT([$kernelsrc])
 	AC_MSG_CHECKING([kernel build directory])
 	if test -z "$kernelbuild"; then
-		if test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
+		if test -e "/lib/modules/$(uname -r)/build"; then
+			kernelbuild=`readlink -f /lib/modules/$(uname -r)/build`
+		elif test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/${target_cpu}
 		elif test -d ${kernelsrc}-obj/${target_cpu}/default; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/default
diff --git a/configure b/configure
index 7876f6a16..c3b08440e 100755
--- a/configure
+++ b/configure
@@ -11676,8 +11676,11 @@ fi
 	{ $as_echo "$as_me:$LINENO: checking kernel source directory" >&5
 $as_echo_n "checking kernel source directory... " >&6; }
 	if test -z "$kernelsrc"; then
-		headersdir="/lib/modules/$(uname -r)/build"
-		if test -e "$headersdir"; then
+		if test -e "/lib/modules/$(uname -r)/source"; then
+			headersdir="/lib/modules/$(uname -r)/source"
+			sourcelink=$(readlink -f "$headersdir")
+		elif test -e "/lib/modules/$(uname -r)/build"; then
+			headersdir="/lib/modules/$(uname -r)/build"
 			sourcelink=$(readlink -f "$headersdir")
 		else
 			sourcelink=$(ls -1d /usr/src/kernels/* \
@@ -11711,7 +11714,9 @@ $as_echo "$kernelsrc" >&6; }
 	{ $as_echo "$as_me:$LINENO: checking kernel build directory" >&5
 $as_echo_n "checking kernel build directory... " >&6; }
 	if test -z "$kernelbuild"; then
-		if test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
+		if test -e "/lib/modules/$(uname -r)/build"; then
+			kernelbuild=`readlink -f /lib/modules/$(uname -r)/build`
+		elif test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/${target_cpu}
 		elif test -d ${kernelsrc}-obj/${target_cpu}/default; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/default
@@ -15365,8 +15370,11 @@ fi
 	{ $as_echo "$as_me:$LINENO: checking kernel source directory" >&5
 $as_echo_n "checking kernel source directory... " >&6; }
 	if test -z "$kernelsrc"; then
-		headersdir="/lib/modules/$(uname -r)/build"
-		if test -e "$headersdir"; then
+		if test -e "/lib/modules/$(uname -r)/source"; then
+			headersdir="/lib/modules/$(uname -r)/source"
+			sourcelink=$(readlink -f "$headersdir")
+		elif test -e "/lib/modules/$(uname -r)/build"; then
+			headersdir="/lib/modules/$(uname -r)/build"
 			sourcelink=$(readlink -f "$headersdir")
 		else
 			sourcelink=$(ls -1d /usr/src/kernels/* \
@@ -15400,7 +15408,9 @@ $as_echo "$kernelsrc" >&6; }
 	{ $as_echo "$as_me:$LINENO: checking kernel build directory" >&5
 $as_echo_n "checking kernel build directory... " >&6; }
 	if test -z "$kernelbuild"; then
-		if test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
+		if test -e "/lib/modules/$(uname -r)/build"; then
+			kernelbuild=`readlink -f /lib/modules/$(uname -r)/build`
+		elif test -d ${kernelsrc}-obj/${target_cpu}/${target_cpu}; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/${target_cpu}
 		elif test -d ${kernelsrc}-obj/${target_cpu}/default; then
 			kernelbuild=${kernelsrc}-obj/${target_cpu}/default