diff -up Mesa-7.11/src/mesa/drivers/dri/sis/sis_context.h.jx Mesa-7.11/src/mesa/drivers/dri/sis/sis_context.h
--- Mesa-7.11/src/mesa/drivers/dri/sis/sis_context.h.jx	2010-12-14 16:43:15.000000000 -0500
+++ Mesa-7.11/src/mesa/drivers/dri/sis/sis_context.h	2011-09-09 11:47:56.454465358 -0400
@@ -405,7 +405,7 @@ struct sis_context
 #elif defined(__ia64__)
 #define MMIO_WMB()	__asm __volatile("mf" : : : "memory")
 #else
-#error platform needs WMB
+#define MMIO_WMB()	__sync_synchronize()
 #endif
 
 #define mEndPrimitive()  \