[PATCH] VT binding: Make VT binding a Kconfig option

To enable this feature, CONFIG_VT_HW_CONSOLE_BINDING must be set to 'y'.  This
feature will default to 'n' to minimize users accidentally corrupting their
virtual terminals.
Signed-off-by: NAntonino Daplas <adaplas@pol.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/char/Kconfig

@@ -62,6 +62,23 @@ config HW_CONSOLE
 	depends on VT && !S390 && !UML
 	default y
 
+config VT_HW_CONSOLE_BINDING
+       bool "Support for binding and unbinding console drivers"
+       depends on HW_CONSOLE
+       default n
+       ---help---
+         The virtual terminal is the device that interacts with the physical
+         terminal through console drivers. On these systems, at least one
+         console driver is loaded. In other configurations, additional console
+         drivers may be enabled, such as the framebuffer console. If more than
+         1 console driver is enabled, setting this to 'y' will allow you to
+         select the console driver that will serve as the backend for the
+         virtual terminals.
+
+	 See <file:Documentation/console/console.txt> for more
+	 information. For framebuffer console users, please refer to
+	 <file:Documentation/fb/fbcon.txt>.
+
 config SERIAL_NONSTANDARD
 	bool "Non-standard serial port support"
 	---help---

drivers/char/vt.c

@@ -2691,22 +2691,6 @@ int __init vty_init(void)
 
 static struct class *vtconsole_class;
 
-static int con_is_graphics(const struct consw *csw, int first, int last)
-{
-	int i, retval = 0;
-
-	for (i = first; i <= last; i++) {
-		struct vc_data *vc = vc_cons[i].d;
-
-		if (vc && vc->vc_mode == KD_GRAPHICS) {
-			retval = 1;
-			break;
-		}
-	}
-
-	return retval;
-}
-
 static int bind_con_driver(const struct consw *csw, int first, int last,
 			   int deflt)
 {
@@ -2808,6 +2792,23 @@ static int bind_con_driver(const struct consw *csw, int first, int last,
 	return retval;
 };
 
+#ifdef CONFIG_VT_HW_CONSOLE_BINDING
+static int con_is_graphics(const struct consw *csw, int first, int last)
+{
+	int i, retval = 0;
+
+	for (i = first; i <= last; i++) {
+		struct vc_data *vc = vc_cons[i].d;
+
+		if (vc && vc->vc_mode == KD_GRAPHICS) {
+			retval = 1;
+			break;
+		}
+	}
+
+	return retval;
+}
+
 static int unbind_con_driver(const struct consw *csw, int first, int last,
 			     int deflt)
 {
@@ -2984,6 +2985,16 @@ static int vt_unbind(struct con_driver *con)
 err:
 	return 0;
 }
+#else
+static inline int vt_bind(struct con_driver *con)
+{
+	return 0;
+}
+static inline int vt_unbind(struct con_driver *con)
+{
+	return 0;
+}
+#endif /* CONFIG_VT_HW_CONSOLE_BINDING */
 
 static ssize_t store_bind(struct class_device *class_device,
 			  const char *buf, size_t count)