[PATCH 2.6.20-rc2-git1] start_kernel: Test if irq's got enabled early, barf, and disable them again

[Ard -kwaak- van Breemen <ard@telegraafnet.nl>]

The calls made by parse_parms to other initialization code might
enable interrupts again way too early.
Having interrupts on this early can make systems PANIC when they
initialize the IRQ controllers (which happens later in the code).
This patch detects that irq's are enabled again, barfs about it
and disables them again as a safety net.

Signed-off-by: Ard van Breemen <ard@telegraafnet.nl>

--- linux-2.6.20-rc2-git1/init/main.c.orig	2006-12-30 17:41:13.000000000 +0000
+++ linux-2.6.20-rc2-git1/init/main.c	2006-12-30 17:44:02.000000000 +0000
@@ -538,6 +538,10 @@ asmlinkage void __init start_kernel(void
 	parse_args("Booting kernel", command_line, __start___param,
 		   __stop___param - __start___param,
 		   &unknown_bootoption);
+	if (!irqs_disabled()) {
+		printk(KERN_WARNING "start_kernel(): bug: interrupts were enabled *very* early, fixing it\n");
+		local_irq_disable();
+	}
 	sort_main_extable();
 	trap_init();
 	rcu_init();