diff --git a/sys/powerpc/aim/aim_machdep.c b/sys/powerpc/aim/aim_machdep.c
index 0c476227fd7e..4d7ffa7dfd4e 100644
--- a/sys/powerpc/aim/aim_machdep.c
+++ b/sys/powerpc/aim/aim_machdep.c
@@ -390,6 +390,25 @@ aim_cpu_init(vm_offset_t toc)
 		bcopy(&restorebridge, (void *)EXC_MCHK, trap_offset);
 		bcopy(&restorebridge, (void *)EXC_TRC, trap_offset);
 		bcopy(&restorebridge, (void *)EXC_BPT, trap_offset);
+	} else {
+
+		/*
+		 * Use an IBAT and a DBAT to map the bottom 256M segment.
+		 *
+		 * It is very important to do it *now* to avoid taking a
+		 * fault in .text / .data before the MMU is bootstrapped,
+		 * because until then, the translation data has not been
+		 * copied over from OpenFirmware, so our DSI/ISI will fail
+		 * to find a match.
+		 */
+
+		battable[0x0].batl = BATL(0x00000000, BAT_M, BAT_PP_RW);
+		battable[0x0].batu = BATU(0x00000000, BAT_BL_256M, BAT_Vs);
+
+		__asm (".balign 32; \n"
+		    "mtibatu 0,%0; mtibatl 0,%1; isync; \n"
+		    "mtdbatu 0,%0; mtdbatl 0,%1; isync"
+		    :: "r"(battable[0].batu), "r"(battable[0].batl));
 	}
 	#else
 	trapsize = (size_t)&hypertrapcodeend - (size_t)&hypertrapcode;
diff --git a/sys/powerpc/aim/mmu_oea.c b/sys/powerpc/aim/mmu_oea.c
index 43b2c7480ddf..3b2fda4c852c 100644
--- a/sys/powerpc/aim/mmu_oea.c
+++ b/sys/powerpc/aim/mmu_oea.c
@@ -420,6 +420,32 @@ moea_calc_wimg(vm_paddr_t pa, vm_memattr_t ma)
 	return pte_lo;
 }
 
+/*
+ * Translate OFW translations into VM attributes.
+ */
+static __inline vm_memattr_t
+moea_bootstrap_convert_wimg(uint32_t mode)
+{
+
+	switch (mode) {
+	case (PTE_I | PTE_G):
+		/* PCI device memory */
+		return VM_MEMATTR_UNCACHEABLE;
+	case (PTE_M):
+		/* Explicitly coherent */
+		return VM_MEMATTR_CACHEABLE;
+	case 0: /* Default claim */
+	case 2: /* Alternate PP bits set by OF for the original payload */
+		/* "Normal" memory. */
+		return VM_MEMATTR_DEFAULT;
+
+	default:
+		/* Err on the side of caution for unknowns */
+		/* XXX should we panic instead? */
+		return VM_MEMATTR_UNCACHEABLE;
+	}
+}
+
 static void
 tlbie(vm_offset_t va)
 {
@@ -670,13 +696,6 @@ moea_bootstrap(vm_offset_t kernelstart, vm_offset_t kernelend)
 	vm_size_t	size, physsz, hwphyssz;
 	vm_offset_t	pa, va, off;
 	void		*dpcpu;
-	register_t	msr;
-
-        /*
-         * Set up BAT0 to map the lowest 256 MB area
-         */
-        battable[0x0].batl = BATL(0x00000000, BAT_M, BAT_PP_RW);
-        battable[0x0].batu = BATU(0x00000000, BAT_BL_256M, BAT_Vs);
 
 	/*
 	 * Map PCI memory space.
@@ -693,24 +712,7 @@ moea_bootstrap(vm_offset_t kernelstart, vm_offset_t kernelend)
 	battable[0xb].batl = BATL(0xb0000000, BAT_I|BAT_G, BAT_PP_RW);
 	battable[0xb].batu = BATU(0xb0000000, BAT_BL_256M, BAT_Vs);
 
-	/*
-	 * Map obio devices.
-	 */
-	battable[0xf].batl = BATL(0xf0000000, BAT_I|BAT_G, BAT_PP_RW);
-	battable[0xf].batu = BATU(0xf0000000, BAT_BL_256M, BAT_Vs);
-
-	/*
-	 * Use an IBAT and a DBAT to map the bottom segment of memory
-	 * where we are. Turn off instruction relocation temporarily
-	 * to prevent faults while reprogramming the IBAT.
-	 */
-	msr = mfmsr();
-	mtmsr(msr & ~PSL_IR);
-	__asm (".balign 32; \n"
-	       "mtibatu 0,%0; mtibatl 0,%1; isync; \n"
-	       "mtdbatu 0,%0; mtdbatl 0,%1; isync"
-	    :: "r"(battable[0].batu), "r"(battable[0].batl));
-	mtmsr(msr);
+	powerpc_sync();
 
 	/* map pci space */
 	__asm __volatile("mtdbatu 1,%0" :: "r"(battable[8].batu));
@@ -910,15 +912,21 @@ moea_bootstrap(vm_offset_t kernelstart, vm_offset_t kernelend)
 			/*
 			 * If the mapping is 1:1, let the RAM and device
 			 * on-demand BAT tables take care of the translation.
+			 *
+			 * However, always enter mappings for segment 16,
+			 * which is mixed-protection and therefore not
+			 * compatible with a BAT entry.
 			 */
-			if (translations[i].om_va == translations[i].om_pa)
-				continue;
+			if ((translations[i].om_va >> ADDR_SR_SHFT) != 0xf &&
+				translations[i].om_va == translations[i].om_pa)
+					continue;
 
 			/* Enter the pages */
 			for (off = 0; off < translations[i].om_len;
 			    off += PAGE_SIZE)
-				moea_kenter(translations[i].om_va + off,
-					    translations[i].om_pa + off);
+				moea_kenter_attr(translations[i].om_va + off,
+				    translations[i].om_pa + off,
+				    moea_bootstrap_convert_wimg(translations[i].om_mode));
 		}
 	}