[3/7] Xen VMM patch set : runtime disable of VT console

[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@cl.cam.ac.uk

---


diff -Nurp pristine-linux-2.6.10-rc2/drivers/char/tty_io.c tmp-linux-2.6.10-rc2-xen.patch/drivers/char/tty_io.c
--- pristine-linux-2.6.10-rc2/drivers/char/tty_io.c	2004-11-15 01:27:52.000000000 +0000
+++ tmp-linux-2.6.10-rc2-xen.patch/drivers/char/tty_io.c	2004-11-18 20:10:26.000000000 +0000
@@ -131,6 +131,8 @@ 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 */
@@ -2964,14 +2966,19 @@ static int __init tty_init(void)
 #endif
 
 #ifdef CONFIG_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)
-		panic("Couldn't register /dev/tty0 driver\n");
-	devfs_mk_cdev(MKDEV(TTY_MAJOR, 0), S_IFCHR|S_IRUSR|S_IWUSR, "vc/0");
-	class_simple_device_add(tty_class, MKDEV(TTY_MAJOR, 0), NULL, "tty0");
+	if (console_use_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)
+			panic("Couldn't register /dev/tty0 driver\n");
+		devfs_mk_cdev(MKDEV(TTY_MAJOR, 0), S_IFCHR|S_IRUSR|S_IWUSR,
+			      "vc/0");
+		class_simple_device_add(tty_class, MKDEV(TTY_MAJOR, 0), NULL,
+					"tty0");
 
-	vty_init();
+		vty_init();
+	}
 #endif
 	return 0;
 }