diff --git a/sys/arch/sparc/dev/obio.c b/sys/arch/sparc/dev/obio.c
index f47f576692d5..a40a3917356a 100644
--- a/sys/arch/sparc/dev/obio.c
+++ b/sys/arch/sparc/dev/obio.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: obio.c,v 1.64 2003/07/15 00:04:55 lukem Exp $	*/
+/*	$NetBSD: obio.c,v 1.65 2004/06/27 18:24:47 pk Exp $	*/
 
 /*-
  * Copyright (c) 1997,1998 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: obio.c,v 1.64 2003/07/15 00:04:55 lukem Exp $");
+__KERNEL_RCSID(0, "$NetBSD: obio.c,v 1.65 2004/06/27 18:24:47 pk Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -99,28 +99,8 @@ static	int _obio_bus_map __P((bus_space_tag_t, bus_addr_t,
 			       bus_size_t, int,
 			       vaddr_t, bus_space_handle_t *));
 
-static struct sparc_bus_space_tag obio_space_tag = {
-	NULL,				/* cookie */
-	NULL,				/* parent bus tag */
-	NULL,				/* ranges */
-	0,				/* nranges */
-	_obio_bus_map,			/* bus_space_map */ 
-	NULL,				/* bus_space_unmap */
-	NULL,				/* bus_space_subregion */
-	NULL,				/* bus_space_barrier */ 
-	obio_bus_mmap,			/* bus_space_mmap */ 
-	NULL,				/* bus_intr_establish */
-#if __FULL_SPARC_BUS_SPACE
-	NULL,				/* read_1 */
-	NULL,				/* read_2 */
-	NULL,				/* read_4 */
-	NULL,				/* read_8 */
-	NULL,				/* write_1 */
-	NULL,				/* write_2 */
-	NULL,				/* write_4 */
-	NULL,				/* write_8 */
-#endif
-}; 
+/* There's at most one obio bus, so we can allocate the bus tag statically */
+static struct sparc_bus_space_tag obio_space_tag;
 #endif
 
 /*
@@ -174,8 +154,11 @@ obioattach(parent, self, aux)
 		sc->sc_bustag = ma->ma_bustag;
 		sc->sc_dmatag = ma->ma_dmatag;
 
+		memcpy(&obio_space_tag, sc->sc_bustag, sizeof(obio_space_tag));
 		obio_space_tag.cookie = sc;
 		obio_space_tag.parent = sc->sc_bustag;
+		obio_space_tag.sparc_bus_map = _obio_bus_map;
+		obio_space_tag.sparc_bus_mmap = obio_bus_mmap;
 
 		oa.ma = ma;
 
@@ -245,13 +228,12 @@ _obio_bus_map(t, ba, size, flags, va, hp)
 	vaddr_t va;
 	bus_space_handle_t *hp;
 {
-	struct obio4_softc *sc = t->cookie;
 
 	if ((flags & OBIO_BUS_MAP_USE_ROM) != 0 &&
 	     obio_find_rom_map(ba, size, hp) == 0)
 		return (0);
 
-	return (bus_space_map2(sc->sc_bustag, ba, size, flags, va, hp));
+	return (bus_space_map2(t->parent, ba, size, flags, va, hp));
 }
 
 paddr_t
@@ -262,9 +244,8 @@ obio_bus_mmap(t, ba, off, prot, flags)
 	int prot;
 	int flags;
 {
-	struct obio4_softc *sc = t->cookie;
 
-	return (bus_space_mmap(sc->sc_bustag, ba, off, prot, flags));
+	return (bus_space_mmap(t->parent, ba, off, prot, flags));
 }
 
 int
diff --git a/sys/arch/sparc/dev/sbus.c b/sys/arch/sparc/dev/sbus.c
index ad92433baa60..31c85020a04b 100644
--- a/sys/arch/sparc/dev/sbus.c
+++ b/sys/arch/sparc/dev/sbus.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: sbus.c,v 1.60 2004/03/17 17:04:59 pk Exp $ */
+/*	$NetBSD: sbus.c,v 1.61 2004/06/27 18:24:47 pk Exp $ */
 
 /*-
  * Copyright (c) 1998 The NetBSD Foundation, Inc.
@@ -81,7 +81,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sbus.c,v 1.60 2004/03/17 17:04:59 pk Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sbus.c,v 1.61 2004/06/27 18:24:47 pk Exp $");
 
 #include <sys/param.h>
 #include <sys/malloc.h>
@@ -703,12 +703,12 @@ sbus_alloc_bustag(sc)
 	if (sbt == NULL)
 		return (NULL);
 
-	bzero(sbt, sizeof *sbt);
+	memcpy(sbt, sc->sc_bustag, sizeof(*sbt));
 	sbt->cookie = sc;
 	sbt->parent = sc->sc_bustag;
-	sbt->sparc_bus_map = sc->sc_bustag->sparc_bus_map;
-	sbt->sparc_bus_mmap = sc->sc_bustag->sparc_bus_mmap;
 	sbt->sparc_intr_establish = sbus_intr_establish;
+	sbt->ranges = NULL;
+	sbt->nranges = 0;
 	return (sbt);
 }
 
diff --git a/sys/arch/sparc/include/autoconf.h b/sys/arch/sparc/include/autoconf.h
index 65b94f89dc22..3614578ae216 100644
--- a/sys/arch/sparc/include/autoconf.h
+++ b/sys/arch/sparc/include/autoconf.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: autoconf.h,v 1.37 2003/08/07 16:29:38 agc Exp $ */
+/*	$NetBSD: autoconf.h,v 1.38 2004/06/27 18:24:46 pk Exp $ */
 
 /*-
  * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@@ -186,4 +186,4 @@ struct device *getdevunit __P((char *, int));
 int	romgetcursoraddr __P((int **, int **));
 
 int	bus_translate_address_generic(struct openprom_range *, int,
-	    bus_addr_t, bus_addr_t *);
+	    bus_addr_t *);
diff --git a/sys/arch/sparc/include/bus.h b/sys/arch/sparc/include/bus.h
index 48fd93fe1dfb..7753036eaf07 100644
--- a/sys/arch/sparc/include/bus.h
+++ b/sys/arch/sparc/include/bus.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: bus.h,v 1.40 2003/11/16 11:09:07 pk Exp $	*/
+/*	$NetBSD: bus.h,v 1.41 2004/06/27 18:24:46 pk Exp $	*/
 
 /*-
  * Copyright (c) 1996, 1997, 1998, 2001 The NetBSD Foundation, Inc.
@@ -86,20 +86,6 @@ typedef u_long		bus_size_t;
 #define	BUS_ADDR(io, pa)	\
 	((((u_int64_t)(u_int32_t)(io))<<32) | (u_int32_t)(pa))
 
-/*
- * If __FULL_SPARC_BUS_SPACE is not defined, define it to 0.  We normally
- * don't need to deal with bus_space_{read,write}*() needing to be
- * functions rather than simple memory accesses.  We expose the option
- * to the user via FULL_SPARC_BUS_SPACE.
- */
-#ifdef FULL_SPARC_BUS_SPACE
-#define __FULL_SPARC_BUS_SPACE  1
-#endif
-
-#ifndef __FULL_SPARC_BUS_SPACE
-#define __FULL_SPARC_BUS_SPACE  0
-#endif
-
 #define __BUS_SPACE_HAS_STREAM_METHODS	1
 
 /*
@@ -160,7 +146,6 @@ struct sparc_bus_space_tag {
 				void *,			/*handler arg*/
 				void (*)(void)));	/*optional fast vector*/
 
-#if __FULL_SPARC_BUS_SPACE
 	u_int8_t (*sparc_read_1) __P((
 				bus_space_tag_t space,
 				bus_space_handle_t handle,
@@ -204,26 +189,8 @@ struct sparc_bus_space_tag {
 				bus_space_handle_t handle,
 				bus_size_t offset,
 				u_int64_t value));
-#endif
 };
 
-#if 0
-/*
- * The following macro could be used to generate the bus_space*() functions
- * but it uses a gcc extension and is ANSI-only.
-#define PROTO_bus_space_xxx		__P((bus_space_tag_t t, ...))
-#define RETURNTYPE_bus_space_xxx	void *
-#define BUSFUN(name, returntype, t, args...)			\
-	__inline__ RETURNTYPE_##name				\
-	bus_##name PROTO_##name					\
-	{							\
-		while (t->sparc_##name == NULL)			\
-			t = t->parent;				\
-		return (*(t)->sparc_##name)(t, args);		\
-	}
- */
-#endif
-
 /*
  * Bus space function prototypes.
  * In bus_space_map2(), supply a special virtual address only if you
@@ -281,12 +248,6 @@ static void	*bus_intr_establish2 __P((
 				void (*)(void)));	/*optional fast vector*/
 
 
-/* This macro finds the first "upstream" implementation of method `f' */
-#define _BS_CALL(t,f)			\
-	while (t->f == NULL)		\
-		t = t->parent;		\
-	return (*(t)->f)
-
 static __inline__ int
 bus_space_map(t, a, s, f, hp)
 	bus_space_tag_t	t;
@@ -295,7 +256,7 @@ bus_space_map(t, a, s, f, hp)
 	int		f;
 	bus_space_handle_t *hp;
 {
-	_BS_CALL(t, sparc_bus_map)(t, a, s, f, (vaddr_t)0, hp);
+	return (*t->sparc_bus_map)(t, a, s, f, (vaddr_t)0, hp);
 }
 
 static __inline__ int
@@ -307,7 +268,7 @@ bus_space_map2(t, a, s, f, v, hp)
 	vaddr_t		v;
 	bus_space_handle_t *hp;
 {
-	_BS_CALL(t, sparc_bus_map)(t, a, s, f, v, hp);
+	return (*t->sparc_bus_map)(t, a, s, f, v, hp);
 }
 
 static __inline__ int
@@ -316,7 +277,7 @@ bus_space_unmap(t, h, s)
 	bus_space_handle_t h;
 	bus_size_t	s;
 {
-	_BS_CALL(t, sparc_bus_unmap)(t, h, s);
+	return (*t->sparc_bus_unmap)(t, h, s);
 }
 
 static __inline__ int
@@ -327,7 +288,7 @@ bus_space_subregion(t, h, o, s, hp)
 	bus_size_t	s;
 	bus_space_handle_t *hp;
 {
-	_BS_CALL(t, sparc_bus_subregion)(t, h, o, s, hp);
+	return (*t->sparc_bus_subregion)(t, h, o, s, hp);
 }
 
 static __inline__ paddr_t
@@ -338,7 +299,7 @@ bus_space_mmap(t, a, o, p, f)
 	int		p;
 	int		f;
 {
-	_BS_CALL(t, sparc_bus_mmap)(t, a, o, p, f);
+	return (*t->sparc_bus_mmap)(t, a, o, p, f);
 }
 
 static __inline__ void *
@@ -349,7 +310,7 @@ bus_intr_establish(t, p, l, h, a)
 	int	(*h)__P((void *));
 	void	*a;
 {
-	_BS_CALL(t, sparc_intr_establish)(t, p, l, h, a, NULL);
+	return (*t->sparc_intr_establish)(t, p, l, h, a, NULL);
 }
 
 static __inline__ void *
@@ -361,7 +322,7 @@ bus_intr_establish2(t, p, l, h, a, v)
 	void	*a;
 	void	(*v)__P((void));
 {
-	_BS_CALL(t, sparc_intr_establish)(t, p, l, h, a, v);
+	return (*t->sparc_intr_establish)(t, p, l, h, a, v);
 }
 
 static __inline__ void
@@ -372,7 +333,7 @@ bus_space_barrier(t, h, o, s, f)
 	bus_size_t s;
 	int f;
 {
-	_BS_CALL(t, sparc_bus_barrier)(t, h, o, s, f);
+	(*t->sparc_bus_barrier)(t, h, o, s, f);
 }
 
 
@@ -452,18 +413,13 @@ static u_int64_t bus_space_read_8 __P((bus_space_tag_t,
 					bus_space_handle_t,
 					bus_size_t));
 
-#if __FULL_SPARC_BUS_SPACE
-
 static __inline__ u_int8_t
 bus_space_read_1(t, h, o)
 	bus_space_tag_t		t;
 	bus_space_handle_t	h;
 	bus_size_t		o;
 {
-	__insn_barrier();
-	return t->sparc_read_1 ?
-		(*t->sparc_read_1)(t, h, o) :
-		bus_space_read_1_real(t, h, o);
+	return (*t->sparc_read_1)(t, h, o);
 }
 
 static __inline__ u_int16_t
@@ -472,10 +428,7 @@ bus_space_read_2(t, h, o)
 	bus_space_handle_t	h;
 	bus_size_t		o;
 {
-	__insn_barrier();
-	return t->sparc_read_2 ?
-		(*t->sparc_read_2)(t, h, o) :
-		bus_space_read_2_real(t, h, o);
+	return (*t->sparc_read_2)(t, h, o);
 }
 
 static __inline__ u_int32_t
@@ -484,10 +437,7 @@ bus_space_read_4(t, h, o)
 	bus_space_handle_t	h;
 	bus_size_t		o;
 {
-	__insn_barrier();
-	return t->sparc_read_4 ?
-		(*t->sparc_read_4)(t, h, o) :
-		bus_space_read_4_real(t, h, o);
+	return (*t->sparc_read_4)(t, h, o);
 }
 
 static __inline__ u_int64_t
@@ -496,14 +446,10 @@ bus_space_read_8(t, h, o)
 	bus_space_handle_t	h;
 	bus_size_t		o;
 {
-	__insn_barrier();
-	return t->sparc_read_8 ?
-		(*t->sparc_read_8)(t, h, o) :
-		bus_space_read_8_real(t, h, o);
+	return (*t->sparc_read_8)(t, h, o);
 }
 
-#else /* __FULL_SPARC_BUS_SPACE */
-
+#if __SLIM_SPARC_BUS_SPACE
 static __inline__ u_int8_t
 bus_space_read_1(t, h, o)
 	bus_space_tag_t		t;
@@ -544,7 +490,7 @@ bus_space_read_8(t, h, o)
 	return bus_space_read_8_real(t, h, o);
 }
 
-#endif /* __FULL_SPARC_BUS_SPACE */
+#endif /* __SLIM_SPARC_BUS_SPACE */
 
 #define bus_space_read_stream_1 bus_space_read_1_real
 #define bus_space_read_stream_2 bus_space_read_2_real
@@ -596,8 +542,6 @@ static void bus_space_write_8 __P((bus_space_tag_t,
 				   bus_size_t,
 				   const u_int64_t));
 
-#if __FULL_SPARC_BUS_SPACE
-
 static __inline__ void
 bus_space_write_1(t, h, o, v)
 	bus_space_tag_t		t;
@@ -605,11 +549,7 @@ bus_space_write_1(t, h, o, v)
 	bus_size_t		o;
 	u_int8_t		v;
 {
-	__insn_barrier();
-	if (t->sparc_write_1)
-		(*t->sparc_write_1)(t, h, o, v);
-	else
-		bus_space_write_1_real(t, h, o, v);
+	(*t->sparc_write_1)(t, h, o, v);
 }
 
 static __inline__ void
@@ -619,11 +559,7 @@ bus_space_write_2(t, h, o, v)
 	bus_size_t		o;
 	u_int16_t		v;
 {
-	__insn_barrier();
-	if (t->sparc_write_2)
-		(*t->sparc_write_2)(t, h, o, v);
-	else
-		bus_space_write_2_real(t, h, o, v);
+	(*t->sparc_write_2)(t, h, o, v);
 }
 
 static __inline__ void
@@ -633,11 +569,7 @@ bus_space_write_4(t, h, o, v)
 	bus_size_t		o;
 	u_int32_t		v;
 {
-	__insn_barrier();
-	if (t->sparc_write_4)
-		(*t->sparc_write_4)(t, h, o, v);
-	else
-		bus_space_write_4_real(t, h, o, v);
+	(*t->sparc_write_4)(t, h, o, v);
 }
 
 static __inline__ void
@@ -647,14 +579,10 @@ bus_space_write_8(t, h, o, v)
 	bus_size_t		o;
 	u_int64_t		v;
 {
-	__insn_barrier();
-	if (t->sparc_write_8)
-		(*t->sparc_write_8)(t, h, o, v);
-	else
-		bus_space_write_8_real(t, h, o, v);
+	(*t->sparc_write_8)(t, h, o, v);
 }
 
-#else /* __FULL_SPARC_BUS_SPACE */
+#if __SLIM_SPARC_BUS_SPACE
 
 static __inline__ void
 bus_space_write_1(t, h, o, v)
@@ -700,7 +628,7 @@ bus_space_write_8(t, h, o, v)
 	bus_space_write_8_real(t, h, o, v);
 }
 
-#endif /* __FULL_SPARC_BUS_SPACE */
+#endif /* __SLIM_SPARC_BUS_SPACE */
 
 #define bus_space_write_stream_1 bus_space_write_1_real
 #define bus_space_write_stream_2 bus_space_write_2_real
@@ -785,14 +713,6 @@ bus_space_read_multi_8(t, h, o, a, c)
 		*a++ = bus_space_read_8(t, h, o);
 }
 
-#ifndef __FULL_SPARC_BUS_SPACE
-#define bus_space_read_multi_stream_1 bus_space_read_multi_1
-#define bus_space_read_multi_stream_2 bus_space_read_multi_2
-#define bus_space_read_multi_stream_4 bus_space_read_multi_4
-#define bus_space_read_multi_stream_8 bus_space_read_multi_8
-
-#else
-
 #define bus_space_read_multi_stream_1 bus_space_read_multi_1
 
 static void bus_space_read_multi_stream_2 __P((bus_space_tag_t,
@@ -846,8 +766,6 @@ bus_space_read_multi_stream_8(t, h, o, a, c)
 		*a++ = bus_space_read_8_real(t, h, o);
 }
 
-#endif	/* __FULL_SPARC_BUS_SPACE */
-
 /*
  *	void bus_space_write_multi_N __P((bus_space_tag_t tag,
  *	    bus_space_handle_t bsh, bus_size_t offset,
@@ -920,15 +838,6 @@ bus_space_write_multi_8(t, h, o, a, c)
 		bus_space_write_8(t, h, o, *a++);
 }
 
-#ifndef __FULL_SPARC_BUS_SPACE
-
-#define bus_space_write_multi_stream_1 bus_space_write_multi_1
-#define bus_space_write_multi_stream_2 bus_space_write_multi_2
-#define bus_space_write_multi_stream_4 bus_space_write_multi_4
-#define bus_space_write_multi_stream_8 bus_space_write_multi_8
-
-#else
-
 #define bus_space_write_multi_stream_1 bus_space_write_multi_1
 
 static void bus_space_write_multi_stream_2 __P((bus_space_tag_t,
@@ -980,7 +889,6 @@ bus_space_write_multi_stream_8(t, h, o, a, c)
 		bus_space_write_8_real(t, h, o, *a++);
 }
 
-#endif	/* __FULL_SPARC_BUS_SPACE */
 
 /*
  *	void bus_space_set_multi_N __P((bus_space_tag_t tag,
diff --git a/sys/arch/sparc/sparc/cpuunit.c b/sys/arch/sparc/sparc/cpuunit.c
index 5341a5a4ff6b..480e2ac64ead 100644
--- a/sys/arch/sparc/sparc/cpuunit.c
+++ b/sys/arch/sparc/sparc/cpuunit.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: cpuunit.c,v 1.10 2004/03/17 17:04:59 pk Exp $	*/
+/*	$NetBSD: cpuunit.c,v 1.11 2004/06/27 18:24:46 pk Exp $	*/
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cpuunit.c,v 1.10 2004/03/17 17:04:59 pk Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cpuunit.c,v 1.11 2004/06/27 18:24:46 pk Exp $");
 
 #include <sys/param.h>
 #include <sys/malloc.h>
@@ -93,6 +93,7 @@ cpuunit_attach(struct device *parent, struct device *self, void *aux)
 	struct cpuunit_softc *sc = (void *) self;
 	struct mainbus_attach_args *ma = aux;
 	int node, error;
+	bus_space_tag_t sbt;
 
 	sc->sc_node = ma->ma_node;
 	sc->sc_st = ma->ma_bustag;
@@ -105,19 +106,18 @@ cpuunit_attach(struct device *parent, struct device *self, void *aux)
 	/*
 	 * Initialize the bus space tag we pass on to our children.
 	 */
-	sc->sc_bustag = malloc(sizeof(*sc->sc_bustag), M_DEVBUF,
-	    M_WAITOK|M_ZERO);
-	sc->sc_bustag->cookie = sc;
-	sc->sc_bustag->parent = sc->sc_st;
-	sc->sc_bustag->sparc_bus_map = sc->sc_st->sparc_bus_map;
-	sc->sc_bustag->sparc_bus_mmap = sc->sc_st->sparc_bus_mmap;
+	sbt = sc->sc_bustag = malloc(sizeof(*sbt), M_DEVBUF, M_WAITOK);
+	memcpy(sbt, sc->sc_st, sizeof(*sbt));
+	sbt->cookie = sc;
+	sbt->parent = sc->sc_st;
+	sbt->nranges = 0;
+	sbt->ranges = NULL;
 
 	/*
 	 * Collect address translations from the OBP.
 	 */
 	error = prom_getprop(sc->sc_node, "ranges",
-	    sizeof(struct openprom_range), &sc->sc_bustag->nranges,
-	    &sc->sc_bustag->ranges);
+	    sizeof(struct openprom_range), &sbt->nranges, &sbt->ranges);
 	if (error) {
 		printf("%s: error %d getting \"ranges\" property\n",
 		    sc->sc_dev.dv_xname, error);
@@ -129,7 +129,7 @@ cpuunit_attach(struct device *parent, struct device *self, void *aux)
 	     node = nextsibling(node)) {
 		struct cpuunit_attach_args cpua;
 
-		if (cpuunit_setup_attach_args(sc, sc->sc_bustag, node, &cpua))
+		if (cpuunit_setup_attach_args(sc, sbt, node, &cpua))
 			panic("cpuunit_attach: failed to set up attach args");
 
 		(void) config_found(&sc->sc_dev, &cpua, cpuunit_print);
diff --git a/sys/arch/sparc/sparc/machdep.c b/sys/arch/sparc/sparc/machdep.c
index 6eba0751bb79..0c82d7268e71 100644
--- a/sys/arch/sparc/sparc/machdep.c
+++ b/sys/arch/sparc/sparc/machdep.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: machdep.c,v 1.248 2004/04/27 11:25:24 pk Exp $ */
+/*	$NetBSD: machdep.c,v 1.249 2004/06/27 18:24:46 pk Exp $ */
 
 /*-
  * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
@@ -78,7 +78,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.248 2004/04/27 11:25:24 pk Exp $");
+__KERNEL_RCSID(0, "$NetBSD: machdep.c,v 1.249 2004/06/27 18:24:46 pk Exp $");
 
 #include "opt_compat_netbsd.h"
 #include "opt_compat_sunos.h"
@@ -2142,9 +2142,9 @@ static void     sparc_bus_barrier __P(( bus_space_tag_t, bus_space_handle_t,
  */
 int
 bus_translate_address_generic(struct openprom_range *ranges, int nranges,
-    bus_addr_t addr, bus_addr_t *addrp)
+    bus_addr_t *bap)
 {
-	int i, space = BUS_ADDR_IOSPACE(addr);
+	int i, space = BUS_ADDR_IOSPACE(*bap);
 
 	for (i = 0; i < nranges; i++) {
 		struct openprom_range *rp = &ranges[i];
@@ -2153,8 +2153,8 @@ bus_translate_address_generic(struct openprom_range *ranges, int nranges,
 			continue;
 
 		/* We've found the connection to the parent bus. */
-		*addrp = BUS_ADDR(rp->or_parent_space,
-		    rp->or_parent_base + BUS_ADDR_PADDR(addr));
+		*bap = BUS_ADDR(rp->or_parent_space,
+		    rp->or_parent_base + BUS_ADDR_PADDR(*bap));
 		return (0);
 	}
 
@@ -2172,17 +2172,28 @@ sparc_bus_map(t, ba, size, flags, va, hp)
 	vaddr_t v;
 	paddr_t pa;
 	unsigned int pmtype;
+	bus_space_tag_t pt;
 static	vaddr_t iobase;
 
-	if (t->ranges != NULL) {
-		bus_addr_t addr;
-		int error;
+	/*
+	 * This base class bus map function knows about address range
+	 * translation so bus drivers that need no other special
+	 * handling can just keep this method in their tags.
+	 *
+	 * We expect to resolve range translations iteratively, but allow
+	 * for recursion just in case.
+	 */
+	while ((pt = t->parent) != NULL) {
+		if (t->ranges != NULL) {
+			int error;
 
-		error = bus_translate_address_generic(t->ranges, t->nranges,
-		    ba, &addr);
-		if (error)
-			return (error);
-		return (bus_space_map2(t->parent, addr, size, flags, va, hp));
+			if ((error = bus_translate_address_generic(
+					t->ranges, t->nranges, &ba)) != 0)
+				return (error);
+		}
+		if (pt->sparc_bus_map != sparc_bus_map)
+			return (bus_space_map2(pt, ba, size, flags, va, hp));
+		t = pt;
 	}
 
 	if (iobase == 0)
@@ -2256,16 +2267,22 @@ sparc_bus_mmap(t, ba, off, prot, flags)
 {
 	u_int pmtype;
 	paddr_t pa;
+	bus_space_tag_t pt;
 
-	if (t->ranges != NULL) {
-		bus_addr_t addr;
-		int error;
+	/*
+	 * Base class bus mmap function; see also sparc_bus_map
+	 */
+	while ((pt = t->parent) != NULL) {
+		if (t->ranges != NULL) {
+			int error;
 
-		error = bus_translate_address_generic(t->ranges, t->nranges,
-		    ba, &addr);
-		if (error)
-			return (-1);
-		return (bus_space_mmap(t->parent, addr, off, prot, flags));
+			if ((error = bus_translate_address_generic(
+					t->ranges, t->nranges, &ba)) != 0)
+				return (-1);
+		}
+		if (pt->sparc_bus_mmap != sparc_bus_mmap)
+			return (bus_space_mmap(pt, ba, off, prot, flags));
+		t = pt;
 	}
 
 	pmtype = PMAP_IOENC(BUS_ADDR_IOSPACE(ba));
@@ -2336,6 +2353,58 @@ void sparc_bus_barrier (t, h, offset, size, flags)
 	return;
 }
 
+static u_int8_t
+sparc_bus_space_read_1(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o)
+{
+	return bus_space_read_1_real(t, h, o);
+}
+
+static u_int16_t
+sparc_bus_space_read_2(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o)
+{
+	return bus_space_read_2_real(t, h, o);
+}
+
+static u_int32_t
+sparc_bus_space_read_4(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o)
+{
+	return bus_space_read_4_real(t, h, o);
+}
+
+static u_int64_t
+sparc_bus_space_read_8(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o)
+{
+	return bus_space_read_8_real(t, h, o);
+}
+
+static void
+sparc_bus_space_write_1(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+			u_int8_t v)
+{
+	bus_space_write_1_real(t, h, o, v);
+}
+
+static void
+sparc_bus_space_write_2(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+			u_int16_t v)
+{
+	bus_space_write_2_real(t, h, o, v);
+}
+
+static void
+sparc_bus_space_write_4(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+			u_int32_t v)
+{
+	bus_space_write_4_real(t, h, o, v);
+}
+
+static void
+sparc_bus_space_write_8(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
+			u_int64_t v)
+{
+	bus_space_write_8_real(t, h, o, v);
+}
+
 struct sparc_bus_space_tag mainbus_space_tag = {
 	NULL,				/* cookie */
 	NULL,				/* parent bus tag */
@@ -2347,14 +2416,13 @@ struct sparc_bus_space_tag mainbus_space_tag = {
 	sparc_bus_barrier,		/* bus_space_barrier */
 	sparc_bus_mmap,			/* bus_space_mmap */
 	sparc_mainbus_intr_establish,	/* bus_intr_establish */
-#if __FULL_SPARC_BUS_SPACE
-	NULL,				/* read_1 */
-	NULL,				/* read_2 */
-	NULL,				/* read_4 */
-	NULL,				/* read_8 */
-	NULL,				/* write_1 */
-	NULL,				/* write_2 */
-	NULL,				/* write_4 */
-	NULL				/* write_8 */
-#endif
+
+	sparc_bus_space_read_1,		/* bus_space_read_1 */
+	sparc_bus_space_read_2,		/* bus_space_read_2 */
+	sparc_bus_space_read_4,		/* bus_space_read_4 */
+	sparc_bus_space_read_8,		/* bus_space_read_8 */
+	sparc_bus_space_write_1,	/* bus_space_write_1 */
+	sparc_bus_space_write_2,	/* bus_space_write_2 */
+	sparc_bus_space_write_4,	/* bus_space_write_4 */
+	sparc_bus_space_write_8		/* bus_space_write_8 */
 };