diff -Nru Mesa-7.10.2.orig//src/glx/dri2.c Mesa-7.10.2/src/glx/dri2.c
--- Mesa-7.10.2.orig//src/glx/dri2.c	2010-12-14 22:43:14.000000000 +0100
+++ Mesa-7.10.2/src/glx/dri2.c	2011-05-10 19:11:44.632223458 +0200
@@ -124,7 +124,7 @@
       }
       aevent->ust = ((CARD64)awire->ust_hi << 32) | awire->ust_lo;
       aevent->msc = ((CARD64)awire->msc_hi << 32) | awire->msc_lo;
-      aevent->sbc = ((CARD64)awire->sbc_hi << 32) | awire->sbc_lo;
+      aevent->sbc = awire->sbc;
       return True;
    }
 #endif