Index: arch/macppc/include/autoconf.h
===================================================================
RCS file: /cvsroot/src/sys/arch/macppc/include/autoconf.h,v
retrieving revision 1.18
diff -p -u -r1.18 autoconf.h
--- arch/macppc/include/autoconf.h	1 Jul 2011 21:02:15 -0000	1.18
+++ arch/macppc/include/autoconf.h	8 Jan 2019 07:17:13 -0000
@@ -34,7 +34,9 @@
 #ifndef _MACHINE_AUTOCONF_H_
 #define _MACHINE_AUTOCONF_H_
 
-#include <sys/bus.h>	/* for bus_space_tag_t */
+#include <sys/bus.h>
+
+#include <prop/proplib.h>
 
 struct confargs {
 	const char *ca_name;
Index: arch/ofppc/include/autoconf.h
===================================================================
RCS file: /cvsroot/src/sys/arch/ofppc/include/autoconf.h,v
retrieving revision 1.15
diff -p -u -r1.15 autoconf.h
--- arch/ofppc/include/autoconf.h	1 Jul 2011 21:02:15 -0000	1.15
+++ arch/ofppc/include/autoconf.h	8 Jan 2019 07:17:13 -0000
@@ -5,6 +5,8 @@
 
 #include <sys/bus.h>
 
+#include <prop/proplib.h>
+
 struct confargs {
 	const char	*ca_name;
 	u_int		ca_node;
Index: arch/powerpc/include/types.h
===================================================================
RCS file: /cvsroot/src/sys/arch/powerpc/include/types.h,v
retrieving revision 1.56
diff -p -u -r1.56 types.h
--- arch/powerpc/include/types.h	27 Jan 2017 17:22:39 -0000	1.56
+++ arch/powerpc/include/types.h	8 Jan 2019 07:17:13 -0000
@@ -87,6 +87,8 @@ typedef __uint32_t tlb_asid_t;		/* for b
 #define	__HAVE___LWP_GETTCB_FAST
 #define	__HAVE___LWP_SETTCB
 #define	__HAVE_TLS_VARIANT_I
+#define	__OPENFIRMIO_OPEN_CHECK_BROKEN
+int __openfirmio_open_check_broken(void);
 
 #if defined(_KERNEL) || defined(_KMEMUSER)
 #define	PCU_FPU		0	/* FPU */
Index: arch/powerpc/powerpc/openfirm.c
===================================================================
RCS file: /cvsroot/src/sys/arch/powerpc/powerpc/openfirm.c,v
retrieving revision 1.26
diff -p -u -r1.26 openfirm.c
--- arch/powerpc/powerpc/openfirm.c	3 Sep 2018 16:29:26 -0000	1.26
+++ arch/powerpc/powerpc/openfirm.c	8 Jan 2019 07:17:13 -0000
@@ -42,6 +42,7 @@ __KERNEL_RCSID(0, "$NetBSD: openfirm.c,v
 #include <uvm/uvm_extern.h>
 
 #include <machine/psl.h>
+#include <machine/autoconf.h>
 
 #include <dev/ofw/openfirm.h>
 
@@ -757,3 +758,11 @@ ofbcopy(const void *src, void *dst, size
 	while (len-- > 0)
 		*dp++ = *sp++;
 }
+
+#ifdef __OPENFIRMIO_OPEN_CHECK_BROKEN
+int
+__openfirmio_open_check_broken(void)
+{
+	return strncmp(model_name, "Pegasos", 7) == 0 ? ENXIO : 0;
+}
+#endif
Index: dev/ofw/openfirmio.c
===================================================================
RCS file: /cvsroot/src/sys/dev/ofw/openfirmio.c,v
retrieving revision 1.13
diff -p -u -r1.13 openfirmio.c
--- dev/ofw/openfirmio.c	25 Jul 2014 08:10:37 -0000	1.13
+++ dev/ofw/openfirmio.c	8 Jan 2019 07:17:13 -0000
@@ -63,10 +63,11 @@ static int openfirmgetstr (int, char *, 
 
 void openfirmattach (int);
 
-dev_type_ioctl(openfirmioctl);
+static dev_type_open(openfirmopen);
+static dev_type_ioctl(openfirmioctl);
 
 const struct cdevsw openfirm_cdevsw = {
-	.d_open = nullopen,
+	.d_open = openfirmopen,
 	.d_close = nullclose,
 	.d_read = noread,
 	.d_write = nowrite,
@@ -117,7 +118,17 @@ openfirmgetstr(int len, char *user, char
 	return (error);
 }
 
-int
+static int
+openfirmopen(dev_t dev, int flag, int mode, struct lwp *l)
+{
+#ifdef __OPENFIRMIO_OPEN_CHECK_BROKEN
+	return __openfirmio_open_check_broken();
+#else
+	return 0;
+#endif
+}
+
+static int
 openfirmioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
 {
 	struct ofiocdesc *of;