diff --git a/sys/ia64/ia64/machdep.c b/sys/ia64/ia64/machdep.c
index 537315117e6a..92bbc64cbfab 100644
--- a/sys/ia64/ia64/machdep.c
+++ b/sys/ia64/ia64/machdep.c
@@ -716,8 +716,8 @@ ia64_init(void)
 	 * handlers. Here we just make sure that they have the largest
 	 * possible page size to minimise TLB usage.
 	 */
-	ia64_set_rr(IA64_RR_BASE(6), (6 << 8) | (PAGE_SHIFT << 2));
-	ia64_set_rr(IA64_RR_BASE(7), (7 << 8) | (PAGE_SHIFT << 2));
+	ia64_set_rr(IA64_RR_BASE(6), (6 << 8) | (LOG2_ID_PAGE_SIZE << 2));
+	ia64_set_rr(IA64_RR_BASE(7), (7 << 8) | (LOG2_ID_PAGE_SIZE << 2));
 	ia64_srlz_d();
 
 	/* Initialize/setup physical memory datastructures */
diff --git a/sys/ia64/ia64/mp_machdep.c b/sys/ia64/ia64/mp_machdep.c
index 74adef402014..4b7bb7b650e8 100644
--- a/sys/ia64/ia64/mp_machdep.c
+++ b/sys/ia64/ia64/mp_machdep.c
@@ -208,8 +208,8 @@ ia64_ap_startup(void)
 	ia64_ap_state.as_trace = 0x100;
 
 	ia64_set_rr(IA64_RR_BASE(5), (5 << 8) | (PAGE_SHIFT << 2) | 1);
-	ia64_set_rr(IA64_RR_BASE(6), (6 << 8) | (PAGE_SHIFT << 2));
-	ia64_set_rr(IA64_RR_BASE(7), (7 << 8) | (PAGE_SHIFT << 2));
+	ia64_set_rr(IA64_RR_BASE(6), (6 << 8) | (LOG2_ID_PAGE_SIZE << 2));
+	ia64_set_rr(IA64_RR_BASE(7), (7 << 8) | (LOG2_ID_PAGE_SIZE << 2));
 	ia64_srlz_d();
 
 	pcpup = ia64_ap_state.as_pcpu;
diff --git a/sys/ia64/include/param.h b/sys/ia64/include/param.h
index c00eb28af8d3..a260a7598ef8 100644
--- a/sys/ia64/include/param.h
+++ b/sys/ia64/include/param.h
@@ -105,6 +105,11 @@
 #endif
 #define	KSTACK_GUARD_PAGES 0		/* pages of kstack guard; 0 disables */
 
+/* The default size of identity mappings in region 6 & 7. */
+#ifndef LOG2_ID_PAGE_SIZE
+#define	LOG2_ID_PAGE_SIZE	16
+#endif
+
 /*
  * Mach derived conversion macros
  */