x86: Emit "mem=nopentium ignored" warning when not supported

Emit warning when "mem=nopentium" is specified on any arch other
than x86_32 (the only that arch supports it).
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
BugLink: http://bugs.launchpad.net/bugs/553464
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
LKML-Reference: <1296783486-23033-2-git-send-email-kamal@canonical.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>

arch/x86/kernel/e820.c

@@ -847,12 +847,15 @@ static int __init parse_memopt(char *p)
 	if (!p)
 		return -EINVAL;
 
-#ifdef CONFIG_X86_32
 	if (!strcmp(p, "nopentium")) {
+#ifdef CONFIG_X86_32
 		setup_clear_cpu_cap(X86_FEATURE_PSE);
 		return 0;
-	}
+#else
+		printk(KERN_WARNING "mem=nopentium ignored! (only supported on x86_32)\n");
+		return -EINVAL;
 #endif
+	}
 
 	userdef = 1;
 	mem_size = memparse(p, &p);