Little console problem in 2.5.30

[Pete Zaitcev <zaitcev@redhat.com>]

Hi, all:

I would appreciate if someone would explain me if the attached patch
does the right thing. The problem is that I do not use the framebuffer,
and use a serial console. Whenever a legacy /sbin/init tries to
open /dev/tty0, the system oopses dereferencing conswitchp in
visual_init().

-- Pete

diff -ur -X dontdiff linux-2.5.30-sp_pbk/drivers/char/console.c linux-2.5.30-sparc/drivers/char/console.c
--- linux-2.5.30-sp_pbk/drivers/char/console.c	Thu Aug  1 14:16:34 2002
+++ linux-2.5.30-sparc/drivers/char/console.c	Sun Aug 18 23:14:20 2002
@@ -652,7 +652,7 @@
 
 int vc_allocate(unsigned int currcons)	/* return 0 on success */
 {
-	if (currcons >= MAX_NR_CONSOLES)
+	if (currcons >= MAX_NR_CONSOLES || conswitchp == NULL)
 		return -ENXIO;
 	if (!vc_cons[currcons].d) {
 	    long p, q;