linux-kernel - [PATCH] printk timestamp post-boot suppression, v2

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Date:	Wed, 27 Aug 2008 13:04:25 -0400
From:	Joe Korty <joe.korty@...r.com>
To:	Mark Brown <broonie@...ena.org.uk>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Simon Farnsworth <simon.farnsworth@...lan.com>
Subject: [PATCH] printk timestamp post-boot suppression, v2

On Wed, Aug 27, 2008 at 12:16:30PM -0400, Mark Brown wrote:
> It'd be nicer if this were optional - syslog typically only logs at
> second resolution and not all systems are going to have logfiles.


Optionally suppress printk timestamping after system boot.

A new config option is introduced, which if selected
suppresses printk timestamping after the boot sequence
is completed.

Signed-off-by: Joe Korty <joe.korty@...r.com>

Index: 2.6.27-rc4-git4/kernel/printk.c
===================================================================
--- 2.6.27-rc4-git4.orig/kernel/printk.c	2008-08-27 09:37:52.000000000 -0400
+++ 2.6.27-rc4-git4/kernel/printk.c	2008-08-27 12:35:14.000000000 -0400
@@ -560,6 +560,12 @@
 #endif
 module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
 
+#if defined(CONFIG_PRINTK_TIME_BOOTONLY)
+#define printk_time_bootonly (system_state == SYSTEM_BOOTING)
+#else
+#define printk_time_bootonly (1)
+#endif
+
 /* Check if we have any console registered that can be called early in boot. */
 static int have_callable_console(void)
 {
@@ -730,7 +736,7 @@
 			printed_len += 3;
 			new_text_line = 0;
 
-			if (printk_time) {
+			if (printk_time && printk_time_bootonly) {
 				/* Follow the token with the time */
 				char tbuf[50], *tp;
 				unsigned tlen;
Index: 2.6.27-rc4-git4/lib/Kconfig.debug
===================================================================
--- 2.6.27-rc4-git4.orig/lib/Kconfig.debug	2008-08-26 16:28:41.000000000 -0400
+++ 2.6.27-rc4-git4/lib/Kconfig.debug	2008-08-27 12:29:34.000000000 -0400
@@ -9,6 +9,17 @@
 	  operations.  This is useful for identifying long delays
 	  in kernel startup.
 
+config PRINTK_TIME_BOOTONLY
+	bool "Only show printk timing during kernel startup"
+	depends on PRINTK_TIME
+	help
+	  If Y is selected, then timing information will
+	  be prefixed to printk output lines only as long
+	  as the kernel startup phase is in operation.
+
+	  If N is selected, then every printk line will
+	  be prefixed with timing information.
+
 config ENABLE_WARN_DEPRECATED
 	bool "Enable __deprecated logic"
 	default y
--
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