[PATCH] x86_64: Add compat_printk and sysctl to turn off compat layer warnings

Sometimes e.g. with crashme the compat layer warnings can be noisy.
Add a way to turn them off by gating all output through compat_printk
that checks a global sysctl. The default is not changed.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/sysctl.c

@@ -73,6 +73,7 @@ extern int printk_ratelimit_burst;
 extern int pid_max_min, pid_max_max;
 extern int sysctl_drop_caches;
 extern int percpu_pagelist_fraction;
+extern int compat_log;
 
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
 int unknown_nmi_panic;
@@ -676,6 +677,16 @@ static ctl_table kern_table[] = {
 	 	.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#endif
+#ifdef CONFIG_COMPAT
+	{
+		.ctl_name	= KERN_COMPAT_LOG,
+		.procname	= "compat-log",
+		.data		= &compat_log,
+		.maxlen		= sizeof (int),
+	 	.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
 #endif
 	{ .ctl_name = 0 }
 };