Subject: systemsim: don't load systemsim_bd when running on real HW

If we don't do this, we crash during bootup

Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
---

Index: linux-2.6/drivers/block/systemsim_bd.c
===================================================================
--- linux-2.6.orig/drivers/block/systemsim_bd.c
+++ linux-2.6/drivers/block/systemsim_bd.c
@@ -45,6 +45,7 @@
 #include <net/sock.h>
 #include <asm/prom.h>
 #include <asm/systemsim.h>
+#include <asm/prom.h>
 
 #include <asm/uaccess.h>
 #include <asm/types.h>
@@ -208,6 +209,18 @@ static struct block_device_operations sy
 
 static spinlock_t systemsim_bd_lock = SPIN_LOCK_UNLOCKED;
 
+static int mambo_detect(void)
+{
+	struct device_node *n;
+
+	n = of_find_node_by_path("/mambo");
+	if (n) {
+		of_node_put(n);
+		return 1;
+	}
+	return 0;
+}
+
 static int __init systemsim_bd_init(void)
 {
 	struct device_node *systemsim;
@@ -221,6 +234,9 @@ static int __init systemsim_bd_init(void
 		return -1;
 	}
 
+	if (!mambo_detect())
+		return -ENODEV;
+
 	/*
 	 * We could detect which disks are configured in openfirmware
 	 * but I think this unnecessarily limits us from being able to