Subject: [patch] xen vt runtime
From: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>

This patch enables the VT console to be disabled at runtime even if it is
built into the kernel.  Arch xen needs this to avoid trying to initialise a VT
in virtual machine that doesn't have access to the console hardware.

Signed-off-by: Ian Pratt <Ian.Pratt@cl.cam.ac.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Gerd Knorr <kraxel@suse.de>
Index: linux-2.6.14/drivers/char/tty_io.c
===================================================================
--- linux-2.6.14.orig/drivers/char/tty_io.c	2005-12-02 11:58:50.000000000 +0100
+++ linux-2.6.14/drivers/char/tty_io.c	2005-12-02 12:03:13.000000000 +0100
@@ -132,6 +132,8 @@ LIST_HEAD(tty_drivers);			/* linked list
    vt.c for deeply disgusting hack reasons */
 DECLARE_MUTEX(tty_sem);
 
+int console_use_vt = 1;
+
 #ifdef CONFIG_UNIX98_PTYS
 extern struct tty_driver *ptm_driver;	/* Unix98 pty masters; for /dev/ptmx */
 extern int pty_limit;		/* Config limit on Unix98 ptys */
@@ -1825,7 +1827,7 @@ retry_open:
 		goto got_driver;
 	}
 #ifdef CONFIG_VT
-	if (device == MKDEV(TTY_MAJOR,0)) {
+	if (console_use_vt && device == MKDEV(TTY_MAJOR,0)) {
 		extern struct tty_driver *console_driver;
 		driver = console_driver;
 		index = fg_console;
@@ -3014,6 +3016,8 @@ static int __init tty_init(void)
 #endif
 
 #ifdef CONFIG_VT
+	if (!console_use_vt)
+		goto out_vt;
 	cdev_init(&vc0_cdev, &console_fops);
 	if (cdev_add(&vc0_cdev, MKDEV(TTY_MAJOR, 0), 1) ||
 	    register_chrdev_region(MKDEV(TTY_MAJOR, 0), 1, "/dev/vc/0") < 0)
@@ -3022,6 +3026,7 @@ static int __init tty_init(void)
 	class_device_create(tty_class, NULL, MKDEV(TTY_MAJOR, 0), NULL, "tty0");
 
 	vty_init();
+ out_vt:
 #endif
 	return 0;
 }