diff --git a/sys/cddl/compat/opensolaris/sys/atomic.h b/sys/cddl/compat/opensolaris/sys/atomic.h
index 9e30f3da666..4546dd97cb7 100644
--- a/sys/cddl/compat/opensolaris/sys/atomic.h
+++ b/sys/cddl/compat/opensolaris/sys/atomic.h
@@ -43,7 +43,7 @@
 
 #if !defined(__LP64__) && !defined(__mips_n32) && \
     !defined(ARM_HAVE_ATOMIC64) && !defined(I386_HAVE_ATOMIC64)
-extern void atomic_add_64(volatile uint64_t *target, int64_t delta);
+extern void atomic_add_64(volatile uint64_t *target, uint64_t delta);
 extern void atomic_dec_64(volatile uint64_t *target);
 extern uint64_t atomic_swap_64(volatile uint64_t *a, uint64_t value);
 extern uint64_t atomic_load_64(volatile uint64_t *a);
diff --git a/sys/conf/files.powerpc b/sys/conf/files.powerpc
index 020b959f303..62fb3b0c15d 100644
--- a/sys/conf/files.powerpc
+++ b/sys/conf/files.powerpc
@@ -76,7 +76,7 @@ dev/uart/uart_cpu_powerpc.c	optional	uart
 dev/usb/controller/ehci_fsl.c	optional	ehci mpc85xx
 dev/vt/hw/ofwfb/ofwfb.c		optional	vt aim
 kern/kern_clocksource.c		standard
-#kern/subr_atomic64.c		optional	powerpc | powerpcspe
+kern/subr_atomic64.c		optional	powerpc | powerpcspe
 kern/subr_dummy_vdso_tc.c	standard
 kern/syscalls.c			optional	ktr
 kern/subr_sfbuf.c		standard
diff --git a/sys/kern/subr_atomic64.c b/sys/kern/subr_atomic64.c
index 8f7982afd23..3c725e95687 100644
--- a/sys/kern/subr_atomic64.c
+++ b/sys/kern/subr_atomic64.c
@@ -27,9 +27,11 @@
 
 #include <sys/cdefs.h>
 #include <sys/param.h>
+#include <sys/kernel.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/smp.h>
+#include <sys/systm.h>
 
 #include <machine/atomic.h>
 #include <machine/sysarch.h>
@@ -72,6 +74,15 @@ struct atomic64_sysarch_args {
 
 #define UNLOCK_A64()	if (smp_started) mtx_unlock(_amtx)
 
+#define ATOMIC64_EMU_UN(op, rt, block, ret) \
+    rt \
+    atomic_##op##_64(volatile u_int64_t *p) {			\
+	u_int64_t tmp __unused;					\
+	LOCK_A64();						\
+	block;							\
+	UNLOCK_A64();						\
+	ret; } struct hack
+
 #define	ATOMIC64_EMU_BIN(op, rt, block, ret) \
     rt \
     atomic_##op##_64(volatile u_int64_t *p, u_int64_t v) {	\
@@ -86,6 +97,7 @@ static struct mtx a64_mtx_pool[A64_POOL_SIZE];
 ATOMIC64_EMU_BIN(add, void, (*p = *p + v), return);
 ATOMIC64_EMU_BIN(clear, void, *p &= ~v, return);
 ATOMIC64_EMU_BIN(fetchadd, u_int64_t, (*p = *p + v, v = *p - v), return (v));
+ATOMIC64_EMU_UN(load, u_int64_t, (tmp = *p), return (tmp));
 ATOMIC64_EMU_BIN(set, void, *p |= v, return);
 ATOMIC64_EMU_BIN(subtract, void, (*p = *p - v), return);
 ATOMIC64_EMU_BIN(store, void, *p = v, return);
@@ -121,7 +133,7 @@ int atomic_fcmpset_64(volatile u_int64_t *p, u_int64_t *old, u_int64_t new)
 }
 
 static void
-atomic64_mtxinit(void)
+atomic64_mtxinit(void *x __unused)
 {
 	int i;
 
@@ -137,7 +149,7 @@ int
 sysarch_atomic64(void *args)
 {
 	struct atomic64_sysarch_args a64_args;
-	u_int64_t p, fv;
+	u_int64_t p;
 	int err;
 
 	err = copyin(args, &a64_args, sizeof(a64_args));
@@ -145,44 +157,45 @@ sysarch_atomic64(void *args)
 	    return (err);
 
 	mtx_lock(&atomic64_user_mtx);
-	err = copyin(a64_args, &p, sizeof(p));
+	err = copyin(a64_args.p, &p, sizeof(p));
 	if (err < 0) {
 		mtx_unlock(&atomic64_user_mtx);
 		goto err;
 	}
-	switch (a64_args->type) {
+	switch (a64_args.type) {
 	case ATOMIC64_ADD:
-		atomic_add_64(&p, a64_args->v);
+		atomic_add_64(&p, a64_args.v);
 		break;
 	case ATOMIC64_CLEAR:
-		atomic_clear_64(&p, a64_args->v);
+		atomic_clear_64(&p, a64_args.v);
 		break;
 	case ATOMIC64_CMPSET:
-		a64_args->rval =
-		    atomic_cmpset_64(p, a64_args->v, a64_args->arg2);
+		a64_args.rval =
+		    atomic_cmpset_64(&p, a64_args.v, a64_args.arg2);
 		break;
 	case ATOMIC64_FCMPSET:
-		a64_args->rval =
-		    atomic_fcmpset_64(p, &a64_args->v, a64_args->arg2);
+		/* XXX arg2 is a pointer */
+		a64_args.rval =
+		    atomic_fcmpset_64(&p, &a64_args.v, a64_args.arg2);
 		break;
 	case ATOMIC64_FETCHADD:
-		atomic_fetchadd_64(&p, a64_args->v);
+		atomic_fetchadd_64(&p, a64_args.v);
 		break;
 	case ATOMIC64_LOAD:
-		a64_args->rval = p;
+		a64_args.rval = p;
 		break;
 	case ATOMIC64_SET:
-		atomic_set_64(&p, a64_args->v);
+		atomic_set_64(&p, a64_args.v);
 		break;
 	case ATOMIC64_SUBTRACT:
-		atomic_subtract_64(&p, a64_args->v);
+		atomic_subtract_64(&p, a64_args.v);
 		break;
 	case ATOMIC64_STORE:
-		copyout(&a64_args->v, a64_args->p, sizeof(a64_args->p));
+		copyout(&a64_args.v, a64_args.p, sizeof(a64_args.p));
 		break;
 	case ATOMIC64_SWAP:
-		a64_args->rval = p;
-		copyout(&a64_args->v, a64_args->p, sizeof(a64_args->p));
+		a64_args.rval = p;
+		copyout(&a64_args.v, a64_args.p, sizeof(a64_args.p));
 		break;
 	};
 
diff --git a/sys/powerpc/powerpc/sys_machdep.c b/sys/powerpc/powerpc/sys_machdep.c
index ab5527ad69e..17edc2659a4 100644
--- a/sys/powerpc/powerpc/sys_machdep.c
+++ b/sys/powerpc/powerpc/sys_machdep.c
@@ -32,6 +32,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/systm.h>
 #include <sys/errno.h>
 #include <sys/sysproto.h>
+#include <machine/sysarch.h>
 
 #ifdef COMPAT_FREEBSD32
 #include <compat/freebsd32/freebsd32_proto.h>
diff --git a/sys/sys/_atomic64e.h b/sys/sys/_atomic64e.h
index e195113ad2d..b48f299cf40 100644
--- a/sys/sys/_atomic64e.h
+++ b/sys/sys/_atomic64e.h
@@ -55,7 +55,7 @@ int	atomic_fcmpset_64(volatile u_int64_t *, u_int64_t *, u_int64_t);
 
 u_int64_t atomic_fetchadd_64(volatile u_int64_t *, u_int64_t);
 
-void	atomic_load_64(volatile u_int64_t *);
+u_int64_t	atomic_load_64(volatile u_int64_t *);
 #define	atomic_load_acq_64	atomic_load_64
 
 void	atomic_readandclear_64(volatile u_int64_t *);