[patch] defer panic for too many items in boot parameter line

[Werner Almesberger <werner@almesberger.net>]

When passing too many unrecognized boot command line options (which
become arguments or environment variables), the 2.6 kernel panics
(unlike 2.4, which just ignores the extra items). Unfortunately,
this happens before the console is initialized, so all you get is a
kernel that dies quickly, for no apparent reason.

This is particularly irritating if using UML with
init=something wi th a lot of ar gu men t s

The patch below delays the panic until after console_init.
It's for 2.6.2 and also works for 2.6.1. Tested on i386 and um.

- Werner

--- linux-2.6.2/init/main.c.orig	2004-02-08 17:13:20.000000000 -0300
+++ linux-2.6.2/init/main.c	2004-02-08 18:06:49.000000000 -0300
@@ -141,6 +141,7 @@
 
 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
+static const char *panic_later, *panic_param;
 
 __setup("profile=", profile_setup);
 
@@ -253,20 +254,27 @@
 		return 0;
 	}
 
+	if (panic_later)
+		return 0;
+
 	if (val) {
 		/* Environment option */
 		unsigned int i;
 		for (i = 0; envp_init[i]; i++) {
-			if (i == MAX_INIT_ENVS)
-				panic("Too many boot env vars at `%s'", param);
+			if (i == MAX_INIT_ENVS) {
+				panic_later = "Too many boot env vars at `%s'";
+				panic_param = param;
+			}
 		}
 		envp_init[i] = param;
 	} else {
 		/* Command line option */
 		unsigned int i;
 		for (i = 0; argv_init[i]; i++) {
-			if (i == MAX_INIT_ARGS)
-				panic("Too many boot init vars at `%s'",param);
+			if (i == MAX_INIT_ARGS) {
+				panic_later = "Too many boot init vars at `%s'";
+				panic_param = param;
+			}
 		}
 		argv_init[i] = param;
 	}
@@ -424,6 +432,8 @@
 	 * this. But we do want output early, in case something goes wrong.
 	 */
 	console_init();
+	if (panic_later)
+		panic(panic_later, panic_param);
 	profile_init();
 	local_irq_enable();
 #ifdef CONFIG_BLK_DEV_INITRD

-- 
  _________________________________________________________________________
 / Werner Almesberger, Buenos Aires, Argentina     werner@almesberger.net /
/_http://www.almesberger.net/____________________________________________/