From fc8f6be5a9bd84e10149770b76ff9353d25ce2a7 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 12 Oct 2009 23:58:47 +0100
Subject: configure: Conditionally build libdrm_intel

Only build libdrm_intel automatically if we have support for atomic
operations. To force configure to build drm pass --enable-intel, which
will cause the configure to error if no support is found. Or pass
--disable-intel to explicitly prevent libdrm_intel from being built.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 configure.ac | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 870c0567..0c216cea 100644
--- a/configure.ac
+++ b/configure.ac
@@ -45,8 +45,8 @@ AC_ARG_ENABLE(udev,	AS_HELP_STRING([--enable-udev],
 
 AC_ARG_ENABLE(intel,
 	      AS_HELP_STRING([--disable-intel],
-	      [Enable support for intel's KMS API (default: enabled)]),
-	      [INTEL=$enableval], [INTEL=yes])
+	      [Enable support for intel's KMS API (default: auto)]),
+	      [INTEL=$enableval], [INTEL=auto])
 
 AC_ARG_ENABLE(nouveau-experimental-api,
 	      AS_HELP_STRING([--enable-nouveau-experimental-api],
@@ -151,9 +151,7 @@ if test "x$HAVE_LIBUDEV" = xyes; then
 fi
 AM_CONDITIONAL(HAVE_LIBUDEV, [test "x$HAVE_LIBUDEV" = xyes])
 
-AM_CONDITIONAL(HAVE_INTEL, [test "x$INTEL" = xyes])
-
-if test "x$INTEL" = xyes; then
+if test "x$INTEL" != "xno"; then
     # Check for atomic intrinsics
     AC_CACHE_CHECK([for native atomic primitives], drm_cv_atomic_primitives,
     [
@@ -170,8 +168,19 @@ if test "x$INTEL" = xyes; then
 	    AC_DEFINE(HAVE_INTEL_ATOMIC_PRIMITIVES, 1,
 		      [Enable if your compiler supports the Intel __sync_* atomic primitives])
     fi
+
+    if test "x$drm_cv_atomic_primitives" = "xnone"; then
+	    if test "x$INTEL" != "xauto"; then
+		    AC_MSG_ERROR([libdrm_intel depends upon atomic operations, which were not found for your compiler/cpu. Try compiling with -march=native, or disable support for Intel GPUs by passing --disable-intel to ./configue])
+	   else
+		    INTEL=no
+	   fi
+    fi
 fi
 
+AM_CONDITIONAL(HAVE_INTEL, [test "x$INTEL" != "xno"])
+
+
 AC_SUBST(WARN_CFLAGS)
 AC_OUTPUT([
 	Makefile
-- 
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