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: linus-2.6/drivers/block/systemsim_bd.c
===================================================================
--- linus-2.6.orig/drivers/block/systemsim_bd.c
+++ linus-2.6/drivers/block/systemsim_bd.c
@@ -45,6 +45,7 @@
 #include <net/sock.h>
 
 #include <asm/systemsim.h>
+#include <asm/prom.h>
 
 #include <linux/devfs_fs_kernel.h>
 
@@ -210,11 +211,26 @@ static struct block_device_operations mb
 
 static spinlock_t mbd_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 mbd_init(void)
 {
 	int err = -ENOMEM;
 	int i;
 
+	if (!mambo_detect())
+		return -ENODEV;
+
 	for (i = 0; i < MAX_MBD; i++) {
 		struct gendisk *disk = alloc_disk(1);
 		if (!disk)