[PATCH 2.6.12] printk: add sysctl to control printk_time

[Mark Whittington <markc@liquidev.com>]

Added a sysctl (KERN_PRINTK_TIME) and by proxy an entry in 
/proc/sys/kernel to enable and disable printk interval information when 
CONFIG_PRINTK_TIME is compiled in.

Signed-off-by: Mark Whittington <markc@liquidev.com>

diff -ruN linux-2.6.12/Documentation/sysctl/kernel.txt linux-2.6.12-work/Documentation/sysctl/kernel.txt
--- linux-2.6.12/Documentation/sysctl/kernel.txt	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.12-work/Documentation/sysctl/kernel.txt	2005-07-20 14:58:15.000000000 -0400
@@ -39,6 +39,7 @@
 - pid_max
 - powersave-nap               [ PPC only ]
 - printk
+- printk_time                 [ CONFIG_PRINTK_TIME=y ]
 - real-root-dev               ==> Documentation/initrd.txt
 - reboot-cmd                  [ SPARC only ]
 - rtsig-max
@@ -260,6 +261,14 @@

 ==============================================================

+printk_time:
+
+If CONFIG_PRINTK_TIME is on at compile time, you can enable
+and disable time printing by echoing 1 or 0 to this file.  You
+can also read the current value from this file.
+
+==============================================================
+
 reboot-cmd: (Sparc only)

 ??? This seems to be a way to give an argument to the Sparc
diff -ruN linux-2.6.12/include/linux/sysctl.h linux-2.6.12-work/include/linux/sysctl.h
--- linux-2.6.12/include/linux/sysctl.h	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.12-work/include/linux/sysctl.h	2005-07-20 14:54:29.000000000 -0400
@@ -136,6 +136,9 @@
 	KERN_UNKNOWN_NMI_PANIC=66, /* int: unknown nmi panic flag */
 	KERN_BOOTLOADER_TYPE=67, /* int: boot loader type */
 	KERN_RANDOMIZE=68, /* int: randomize virtual address space */
+#if defined(CONFIG_PRINTK_TIME)
+	KERN_PRINTK_TIME=69, /* int: printk times enabled */
+#endif
 };


diff -ruN linux-2.6.12/kernel/printk.c linux-2.6.12-work/kernel/printk.c
--- linux-2.6.12/kernel/printk.c	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.12-work/kernel/printk.c	2005-07-20 15:32:03.000000000 -0400
@@ -473,7 +473,8 @@
 }

 #if defined(CONFIG_PRINTK_TIME)
-static int printk_time = 1;
+int printk_time = 1;
+EXPORT_SYMBOL(printk_time);
 #else
 static int printk_time = 0;
 #endif
diff -ruN linux-2.6.12/kernel/sysctl.c linux-2.6.12-work/kernel/sysctl.c
--- linux-2.6.12/kernel/sysctl.c	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.12-work/kernel/sysctl.c	2005-07-20 14:53:54.000000000 -0400
@@ -63,6 +63,7 @@
 extern int pid_max;
 extern int min_free_kbytes;
 extern int printk_ratelimit_jiffies;
+extern int printk_time;
 extern int printk_ratelimit_burst;
 extern int pid_max_min, pid_max_max;

@@ -589,6 +590,16 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec,
 	},
+#if defined(CONFIG_PRINTK_TIME)
+	{
+		.ctl_name	= KERN_PRINTK_TIME,
+		.procname	= "printk_time",
+		.data		= &printk_time,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+	},
+#endif
 	{
 		.ctl_name	= KERN_PRINTK_RATELIMIT,
 		.procname	= "printk_ratelimit",
diff -ruN linux-2.6.12/lib/Kconfig.debug linux-2.6.12-work/lib/Kconfig.debug
--- linux-2.6.12/lib/Kconfig.debug	2005-06-17 15:48:29.000000000 -0400
+++ linux-2.6.12-work/lib/Kconfig.debug	2005-07-20 15:09:07.000000000 -0400
@@ -6,7 +6,9 @@
 	  included in printk output.  This allows you to measure
 	  the interval between kernel operations, including bootup
 	  operations.  This is useful for identifying long delays
-	  in kernel startup.
+	  in kernel startup.  If this option is enabled, you can turn
+          off and on the timing information by echoing a 1 or 0 to
+          /proc/kernel/sys/printk_time.


 config DEBUG_KERNEL
-
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