Make configure builtin-aware.

This patch adds a new option to configure: --enable-linux-builtin. When
this option is used, the following happens:

 - Compilation of kernel modules is disabled.

 - A failure to find UTS_RELEASE is followed by a suggestion to run
   "make prepare" on the kernel source tree.

This patch also adds a new test which tries to compile an empty module
as a basic toolchain sanity test. If it fails and the option was
specified, the error is followed by a suggestion to run "make scripts"
on the kernel source tree.

Signed-off-by: Prakash Surya <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Issue #851

2 files changed, 36 insertions, 6 deletions

diff --git a/config/kernel.m4 b/config/kernel.m4
index c65c58cc0..2fb3fc91b 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -4,6 +4,7 @@ dnl #
 AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL
 	ZFS_AC_SPL
+	ZFS_AC_TEST_MODULE
 	ZFS_AC_KERNEL_CONFIG
 	ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS
 	ZFS_AC_KERNEL_TYPE_FMODE_T
@@ -86,7 +87,7 @@ dnl #
 AC_DEFUN([ZFS_AC_MODULE_SYMVERS], [
 	modpost=$LINUX/scripts/Makefile.modpost
 	AC_MSG_CHECKING([kernel file name for module symbols])
-	AS_IF([test -f "$modpost"], [
+	AS_IF([test "x$enable_linux_builtin" != xyes -a -f "$modpost"], [
 		AS_IF([grep -q Modules.symvers $modpost], [
 			LINUX_SYMBOLS=Modules.symvers
 		], [
@@ -191,7 +192,13 @@ AC_DEFUN([ZFS_AC_KERNEL], [
 		])
 	], [
 		AC_MSG_RESULT([Not found])
-		AC_MSG_ERROR([*** Cannot find UTS_RELEASE definition.])
+		if test "x$enable_linux_builtin" != xyes; then
+			AC_MSG_ERROR([*** Cannot find UTS_RELEASE definition.])
+		else
+			AC_MSG_ERROR([
+	*** Cannot find UTS_RELEASE definition.
+	*** Please run 'make prepare' inside the kernel source tree.])
+		fi
 	])
 
 	AC_MSG_RESULT([$kernsrcver])
@@ -313,6 +320,25 @@ AC_DEFUN([ZFS_AC_SPL], [
 ])
 
 dnl #
+dnl # Basic toolchain sanity check.
+dnl #
+AC_DEFUN([ZFS_AC_TEST_MODULE],
+	[AC_MSG_CHECKING([whether modules can be built])
+	ZFS_LINUX_TRY_COMPILE([],[],[
+		AC_MSG_RESULT([yes])
+	],[
+		AC_MSG_RESULT([no])
+		if test "x$enable_linux_builtin" != xyes; then
+			AC_MSG_ERROR([*** Unable to build an empty module.])
+		else
+			AC_MSG_ERROR([
+	*** Unable to build an empty module.
+	*** Please run 'make scripts' inside the kernel source tree.])
+		fi
+	])
+])
+
+dnl #
 dnl # Certain kernel build options are not supported.  These must be
 dnl # detected at configure time and cause a build failure.  Otherwise
 dnl # modules may be successfully built that behave incorrectly.
diff --git a/config/zfs-build.m4 b/config/zfs-build.m4
index 6bfea5195..8e6b13b24 100644
--- a/config/zfs-build.m4
+++ b/config/zfs-build.m4
@@ -73,6 +73,11 @@ AC_DEFUN([ZFS_AC_CONFIG], [
 		AS_HELP_STRING([--with-config=CONFIG],
 		[Config file 'kernel|user|all|srpm']),
 		[ZFS_CONFIG="$withval"])
+	AC_ARG_ENABLE([linux-builtin],
+		[AC_HELP_STRING([--enable-linux-builtin],
+		[Configure for builtin in-tree kernel modules @<:@default=no@:>@])],
+		[],
+		[enable_linux_builtin=no])
 
 	AC_MSG_CHECKING([zfs config])
 	AC_MSG_RESULT([$ZFS_CONFIG]);
@@ -93,11 +98,10 @@ AC_DEFUN([ZFS_AC_CONFIG], [
 	esac
 
 	AM_CONDITIONAL([CONFIG_USER],
-	               [test "$ZFS_CONFIG" = user] ||
-	               [test "$ZFS_CONFIG" = all])
+		       [test "$ZFS_CONFIG" = user -o "$ZFS_CONFIG" = all])
 	AM_CONDITIONAL([CONFIG_KERNEL],
-	               [test "$ZFS_CONFIG" = kernel] ||
-	               [test "$ZFS_CONFIG" = all])
+		       [test "$ZFS_CONFIG" = kernel -o "$ZFS_CONFIG" = all] &&
+		       [test "x$enable_linux_builtin" != xyes ])
 ])
 
 dnl #