[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: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 44 insertions, 16 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index ed31638bd75c..3610c5729553 100644
--- a/drivers/char/Kconfig
+++ b/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---
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 037d8a3f5882..714d95ff2f1e 100644
--- a/drivers/char/vt.c
+++ b/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 @@ err:
         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)