Index: sys/powerpc/aim/slb.c
===================================================================
--- sys/powerpc/aim/slb.c
+++ sys/powerpc/aim/slb.c
@@ -416,6 +416,7 @@
 	struct slbtnode *root;
 
 	root = uma_zalloc(slbt_zone, M_NOWAIT | M_ZERO);
+	KASSERT(root != NULL, ("unhandled NULL case"));
 	root->ua_level = UAD_ROOT_LEVEL;
 
 	return (root);
Index: sys/powerpc/pseries/platform_chrp.c
===================================================================
--- sys/powerpc/pseries/platform_chrp.c
+++ sys/powerpc/pseries/platform_chrp.c
@@ -141,8 +141,16 @@
 	if (!(mfmsr() & PSL_HV)) {
 		struct mem_region *phys, *avail;
 		int nphys, navail;
+		vm_offset_t off;
+
 		mem_regions(&phys, &nphys, &avail, &navail);
-		realmaxaddr = phys[0].mr_size;
+
+		realmaxaddr = 0;
+		for (i = 0; i < nphys; i++) {
+			off = phys[i].mr_start + phys[i].mr_size;
+			if (off > realmaxaddr)
+				realmaxaddr = off;
+		}
 
 		pmap_mmu_install("mmu_phyp", BUS_PROBE_SPECIFIC);
 		cpu_idle_hook = phyp_cpu_idle;