linux-kernel - [PATCH] add "notime" boot option

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Message-Id: <20070522120938.db67f1e9.randy.dunlap@oracle.com>
Date:	Tue, 22 May 2007 12:09:38 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	lkml <linux-kernel@...r.kernel.org>
Cc:	akpm <akpm@...ux-foundation.org>
Subject: [PATCH] add "notime" boot option

From: Randy Dunlap <randy.dunlap@...cle.com>

Add "notime" boot option to prevent timing data from being printed on
each printk message line.

We've seen a few cases of 'time' data locking problems (possibly
involving netconsole or net drivers).  If a kernel is built with
CONFIG_PRINTK_TIME=y, it may have a boot locking hang.  Booting
with "notime" may (i.e., could) prevent the lock hang and allow the
kernel to boot successfully, without requiring a kernel rebuild.

Signed-off-by: Randy Dunlap <randy.dunlap@...cle.com>
---
 Documentation/kernel-parameters.txt |    2 ++
 kernel/printk.c                     |   10 +++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

--- linux-2622-rc2.orig/Documentation/kernel-parameters.txt
+++ linux-2622-rc2/Documentation/kernel-parameters.txt
@@ -1227,6 +1227,8 @@ and is between 256 and 4096 characters. 
 
 	nosync		[HW,M68K] Disables sync negotiation for all devices.
 
+	notime		Do not print timing data on each printk message line.
+
 	notsc		[BUGS=IA-32] Disable Time Stamp Counter
 
 	nousb		[USB] Disable the USB subsystem
--- linux-2622-rc2.orig/kernel/printk.c
+++ linux-2622-rc2/kernel/printk.c
@@ -458,9 +458,17 @@ static int __init printk_time_setup(char
 	printk_time = 1;
 	return 1;
 }
-
 __setup("time", printk_time_setup);
 
+static int __init printk_notime_setup(char *str)
+{
+	if (*str)
+		return 0;
+	printk_time = 0;
+	return 1;
+}
+__setup("notime", printk_notime_setup);
+
 __attribute__((weak)) unsigned long long printk_clock(void)
 {
 	return sched_clock();
-
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