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Commit 04d2c8c8 authored by Joe Perches's avatar Joe Perches Committed by Linus Torvalds
Browse files

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: default avatarJoe Perches <joe@perches.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b778b3f2

include/linux/kern_levels.h

+14 −11
Original line number Diff line number Diff line 
#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

include/linux/printk.h

+2 −2
Original line number Diff line number Diff line
@@ -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;