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printk: convert the format for KERN_<LEVEL> to a 2 byte pattern

Instead of "<.>", use an ASCII SOH for the KERN_<LEVEL> prefix initiator.

This saves 1 byte per printk, thousands of bytes in a normal kernel.

No output changes are produced as vprintk_emit converts these uses to
"<.>".

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 parent b778b3f commit 04d2c8c83d0e3ac5f78aeede51babb3236200112 @JoePerches JoePerches committed with torvalds Jul 30, 2012
Showing with 16 additions and 13 deletions.
  1. +14 −11 include/linux/kern_levels.h
  2. +2 −2 include/linux/printk.h
@@ -1,22 +1,25 @@
#ifndef __KERN_LEVELS_H__
#define __KERN_LEVELS_H__
-#define KERN_EMERG "<0>" /* system is unusable */
-#define KERN_ALERT "<1>" /* action must be taken immediately */
-#define KERN_CRIT "<2>" /* critical conditions */
-#define KERN_ERR "<3>" /* error conditions */
-#define KERN_WARNING "<4>" /* warning conditions */
-#define KERN_NOTICE "<5>" /* normal but significant condition */
-#define KERN_INFO "<6>" /* informational */
-#define KERN_DEBUG "<7>" /* debug-level messages */
+#define KERN_SOH "\001" /* ASCII Start Of Header */
+#define KERN_SOH_ASCII '\001'
+
+#define KERN_EMERG KERN_SOH "0" /* system is unusable */
+#define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
+#define KERN_CRIT KERN_SOH "2" /* critical conditions */
+#define KERN_ERR KERN_SOH "3" /* error conditions */
+#define KERN_WARNING KERN_SOH "4" /* warning conditions */
+#define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */
+#define KERN_INFO KERN_SOH "6" /* informational */
+#define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
+
+#define KERN_DEFAULT KERN_SOH "d" /* the default kernel loglevel */
-/* Use the default kernel loglevel */
-#define KERN_DEFAULT "<d>"
/*
* Annotation for a "continued" line of log printout (only done after a
* line that had no enclosing \n). Only to be used by core/arch code
* during early bootup (a continued line is not SMP-safe otherwise).
*/
-#define KERN_CONT "<c>"
+#define KERN_CONT KERN_SOH "c"
#endif
View
@@ -9,7 +9,7 @@ extern const char linux_proc_banner[];
static inline int printk_get_level(const char *buffer)
{
- if (buffer[0] == '<' && buffer[1] && buffer[2] == '>') {
+ if (buffer[0] == KERN_SOH_ASCII && buffer[1]) {
switch (buffer[1]) {
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
@@ -27,7 +27,7 @@ static inline const char *printk_skip_level(const char *buffer)
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
case 'c': /* KERN_CONT */
- return buffer + 3;
+ return buffer + 2;
}
}
return buffer;

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