Index: trunk/src/plugins/rt_topo/crbs.h
===================================================================
--- trunk/src/plugins/rt_topo/crbs.h	(revision 1410)
+++ trunk/src/plugins/rt_topo/crbs.h	(revision 1411)
@@ -53,7 +53,8 @@
 	gdl_list_t twonets; /* of crbs_2net_t */
 	htad_t addrs;
 
-	unsigned disable_concave:1;   /* when set to 1, do an all-convex routing */
+	unsigned disable_concave:1;   /* when set to 1, do an all-convex routing (and possibly virtual-concave) */
+	unsigned disable_vconcave:1;  /* when set to 1, so not do the virtual-concave optimization */
 	unsigned enable_mid_virt:1;   /* when set to 1, insert a virtual point in between any two real points in the original cdt; this allows convex-only routing to emulate concave in corridors */
 
 	/* routing */
Index: trunk/src/plugins/rt_topo/crbs_route.c
===================================================================
--- trunk/src/plugins/rt_topo/crbs_route.c	(revision 1410)
+++ trunk/src/plugins/rt_topo/crbs_route.c	(revision 1411)
@@ -317,11 +317,17 @@
 		while(a->grbs_idx < 5) {
 			if (crbs_trace_ast) printf(" try from %s P%ld to P%ld", from_type, curr->pt->uid, pt->gpt->uid);
 
+			if (crbs->disable_vconcave) {
+				if (a->grbs_idx < 3)
+					a->grbs_idx = 3;
+			}
+
 			if (crbs->disable_concave) {
 				if (a->grbs_idx < 2)
 					a->grbs_idx = 2;
 			}
 
+
 			/* prefer concave over convex; order matters when reaching target: first
 			   valid solution will stop the search */
 			switch(a->grbs_idx) {
@@ -663,6 +669,7 @@
 	int res, tries;
 
 	memset(&crbs, 0, sizeof(crbs_t));
+	crbs.disable_vconcave = 1;
 	crbs.disable_concave = 1;
 	crbs.enable_mid_virt = rt_topo_cfg.mid_virt;
 	crbs_init(&crbs, ctx);