clean up kernel messages

PATCH In review Matt Mackall 6 participants 9 messages Apr 1, 2005 – Apr 2, 2005

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Matt Mackall

author

2005-04-01 20:17 UTC #0 lore raw

PATCH 1/1 clean up kernel messages

This patch tidies up those annoying kernel messages. A typical kernel boot now looks like this:

Loading Linux... Uncompressing kernel...
#

See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.

Signed-off-by Matt Mackall <[email protected]>

include/linux/kernel.h +9 -0

Index: af/include/linux/kernel.h
===================================================================
@@ -115,10 +115,19 @@ extern int __kernel_text_address(unsigne
 extern int kernel_text_address(unsigned long addr);
 extern int session_of_pgrp(int pgrp);
 
+#ifdef CONFIG_PRINTK
 asmlinkage int vprintk(const char *fmt, va_list args)
 	__attribute__ ((format (printf, 1, 0)));
 asmlinkage int printk(const char * fmt, ...)
 	__attribute__ ((format (printf, 1, 2)));
+#else
+static inline int vprintk(const char *s, va_list args)
+	__attribute__ ((format (printf, 1, 0)));
+static inline int vprintk(const char *s, va_list args) { return 0; }
+static inline int printk(const char *s, ...)
+	__attribute__ ((format (printf, 1, 2)));
+static inline int printk(const char *s, ...) { return 0; }
+#endif
 
 unsigned long int_sqrt(unsigned long);

init/Kconfig +11 -0

Index: af/init/Kconfig
===================================================================
@@ -275,6 +275,17 @@ config KALLSYMS_EXTRA_PASS
 	   reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
 	   you wait for kallsyms to be fixed.
 
+ 
+config PRINTK
+	default y
+	bool "Enable support for printk" if EMBEDDED
+	help
+	  This option enables normal printk support. Removing it
+	  eliminates most of the message strings from the kernel image
+	  and makes the kernel more or less silent. As this makes it
+	  very difficult to diagnose system problems, saying N here is
+	  strongly discouraged.
+
 config BUG
 	bool "BUG() support" if EMBEDDED
 	default y

kernel/printk.c +21 -6

Index: af/kernel/printk.c
===================================================================
@@ -80,10 +80,6 @@ static int console_locked;
  */
 static DEFINE_SPINLOCK(logbuf_lock);
 
-static char __log_buf[__LOG_BUF_LEN];
-static char *log_buf = __log_buf;
-static int log_buf_len = __LOG_BUF_LEN;
-
 #define LOG_BUF_MASK	(log_buf_len-1)
 #define LOG_BUF(idx) (log_buf[(idx) & LOG_BUF_MASK])

@@ -94,7 +90,6 @@ static int log_buf_len = __LOG_BUF_LEN;
 static unsigned long log_start;	/* Index into log_buf: next char to be read by syslog() */
 static unsigned long con_start;	/* Index into log_buf: next char to be sent to consoles */
 static unsigned long log_end;	/* Index into log_buf: most-recently-written-char + 1 */
-static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
 
 /*
  *	Array of consoles built from command line options (console=)

@@ -115,6 +110,13 @@ static int preferred_console = -1;
 /* Flag: console code may call schedule() */
 static int console_may_schedule;
 
+#ifdef CONFIG_PRINTK
+
+static char __log_buf[__LOG_BUF_LEN];
+static char *log_buf = __log_buf;
+static int log_buf_len = __LOG_BUF_LEN;
+static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */
+
 /*
  *	Setup a list of consoles. Called from init/main.c
  */

@@ -530,6 +532,7 @@ __setup("time", printk_time_setup);
  * then changes console_loglevel may break. This is because console_loglevel
  * is inspected when the actual printing occurs.
  */
+
 asmlinkage int printk(const char *fmt, ...)
 {
 	va_list args;

@@ -650,6 +653,18 @@ out:
 EXPORT_SYMBOL(printk);
 EXPORT_SYMBOL(vprintk);
 
+#else
+
+asmlinkage long sys_syslog(int type, char __user * buf, int len)
+{
+	return 0;
+}
+
+int do_syslog(int type, char __user * buf, int len) { return 0; }
+static void call_console_drivers(unsigned long start, unsigned long end) {}
+
+#endif
+
 /**
  * acquire_console_sem - lock the console system for exclusive use.
  *

@@ -923,7 +938,7 @@ int unregister_console(struct console * 
 	return res;
 }
 EXPORT_SYMBOL(unregister_console);
-	
+
 /**
  * tty_write_message - write a message to a certain tty, not just the console.
  *

arch/i386/kernel/head.S +2 -0

Index: af/arch/i386/kernel/head.S
===================================================================
@@ -380,6 +380,7 @@ rp_sidt:
 	ALIGN
 ignore_int:
 	cld
+#ifdef CONFIG_PRINTK
 	pushl %eax
 	pushl %ecx
 	pushl %edx

@@ -400,6 +401,7 @@ ignore_int:
 	popl %edx
 	popl %ecx
 	popl %eax
+#endif
 	iret
 
 /*

Signature · 1 line

Mathematics is the supreme nostalgia of our time.

Andrew Morton

2005-04-01 20:30 UTC #1 lore raw

Quoted 10 lines · Matt Mackall

This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.

heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.

One problem was that

	printk("foo");

will still cause the string "foo\0" to appear in the kernel image. That was fixed in later gcc's, but it would be interesting to know which compilers get it right.

Quoted 9 lines

Index: af/include/linux/kernel.h
===================================================================
--- af.orig/include/linux/kernel.h 2005-04-01 00:32:18.000000000 -0800
+++ af/include/linux/kernel.h 2005-04-01 10:38:43.000000000 -0800
@@ -115,10 +115,19 @@ extern int __kernel_text_address(unsigne
extern int kernel_text_address(unsigned long addr); extern int session_of_pgrp(int pgrp);

Quoted 13 lines

+#ifdef CONFIG_PRINTK
asmlinkage int vprintk(const char *fmt, va_list args)
__attribute__ ((format (printf, 1, 0)));
asmlinkage int printk(const char * fmt, ...)
__attribute__ ((format (printf, 1, 2)));
+#else
+static inline int vprintk(const char *s, va_list args)
+ __attribute__ ((format (printf, 1, 0)));
+static inline int vprintk(const char *s, va_list args) { return 0; } +static inline int printk(const char *s, ...)
+ __attribute__ ((format (printf, 1, 2)));
+static inline int printk(const char *s, ...) { return 0; } +#endif

Actually printk() is supposed to return the number of chars which it printed. So if someone is doing:

	while (len < 40)
		len += printk("something");

you've gone and made them lock up.

But I think the number of places where we examine the printk return value is near zero.

Matt Mackall

author

2005-04-01 20:48 UTC #2 lore raw

Quoted 8 lines · Andrew Morton

Quoted 7 lines · Matt Mackall
This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#

Quoted 7 lines

Quoted 3 lines
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.
heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.

He's got a bunch of stuff that's not strictly related in there and stuff I've already dealt with (vprintk and the like) and stuff that's still forthcoming (panic tweaks, etc.). I also leave in all the APIs like dmesg, they just no longer do anything.

Quoted 7 lines

One problem was that
	printk("foo");
will still cause the string "foo\0" to appear in the kernel image. That was fixed in later gcc's, but it would be interesting to know which compilers get it right.

Haven't encountered this. I think it should be fine for any compiler that can handle 2.6. This has been in -tiny for nearly a year and a half and no one's complained.

Quoted 5 lines

Quoted 1 line
+static inline int printk(const char *s, ...) { return 0; }
Actually printk() is supposed to return the number of chars which it printed. So if someone is doing:

Quoted 7 lines

	while (len < 40)
		len += printk("something");
you've gone and made them lock up.
But I think the number of places where we examine the printk return value is near zero.

Well in some sense 0 is the proper return but I suppose this could be made to return 1. Small enough not break anything, big enough so that things like the above get unstuck.

Signature · 1 line

Mathematics is the supreme nostalgia of our time.

Steven Rostedt

2005-04-01 21:21 UTC #3 lore raw

Quoted 13 lines · Matt Mackall

Quoted 12 lines · Andrew Morton
Quoted 10 lines · Matt Mackall
This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.

Quoted 8 lines

Quoted 3 lines
heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.
He's got a bunch of stuff that's not strictly related in there and stuff I've already dealt with (vprintk and the like) and stuff that's still forthcoming (panic tweaks, etc.). I also leave in all the APIs like dmesg, they just no longer do anything.

Looking at your other patches, I'm assuming that this is just another April 1st type of patch. Is it?

-- Steve

Steven Rostedt

2005-04-01 21:54 UTC #4 lore raw

Quoted 18 lines · Steven Rostedt

Quoted 17 lines · Matt Mackall
Quoted 15 lines · Andrew Morton
Quoted 10 lines · Matt Mackall
This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.
heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.

Quoted 7 lines

Quoted 4 lines
He's got a bunch of stuff that's not strictly related in there and stuff I've already dealt with (vprintk and the like) and stuff that's still forthcoming (panic tweaks, etc.). I also leave in all the APIs like dmesg, they just no longer do anything.
Looking at your other patches, I'm assuming that this is just another April 1st type of patch. Is it?

Arg! I'm too tired. I took another look at your other patches and they look more legit now. On first glance, I thought you were just bluntly removing BUGs and error messages to quiet things down. But after taking another look, I see that they are more than that. I wouldn't of thought about that on any other day.

Sorry,

-- Steve

Richard B. Johnson

2005-04-01 22:14 UTC #5 lore raw

Quoted 33 lines · Steven Rostedt

Quoted 18 lines · Steven Rostedt
Quoted 17 lines · Matt Mackall
Quoted 15 lines · Andrew Morton
Quoted 10 lines · Matt Mackall
This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.
heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.
Quoted 7 lines
Quoted 4 lines
He's got a bunch of stuff that's not strictly related in there and stuff I've already dealt with (vprintk and the like) and stuff that's still forthcoming (panic tweaks, etc.). I also leave in all the APIs like dmesg, they just no longer do anything.
Looking at your other patches, I'm assuming that this is just another April 1st type of patch. Is it?
Arg! I'm too tired. I took another look at your other patches and they look more legit now. On first glance, I thought you were just bluntly removing BUGs and error messages to quiet things down. But after taking another look, I see that they are more than that. I wouldn't of thought about that on any other day.

Quoted 4 lines

Sorry,
-- Steve

Methinks he still is kidding. We have "quiet" as a parameter now to quiet things down on a boot. Now if he would just get rid of the annoying...

Quoted 1 line

Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Loading Linux... Uncompressing kernel...

He'd have something.

Cheers,
Dick Johnson
Penguin : Linux version 2.6.11 on an i686 machine (5537.79 BogoMips).
Notice : All mail here is now cached for review by Dictator Bush.
98.36% of all statistics are fiction.

Denis Vlasenko

2005-04-02 10:35 UTC #6 lore raw

Quoted 12 lines · Richard B. Johnson

Quoted 12 lines
Quoted 2 lines
Looking at your other patches, I'm assuming that this is just another April 1st type of patch. Is it?
Arg! I'm too tired. I took another look at your other patches and they look more legit now. On first glance, I thought you were just bluntly removing BUGs and error messages to quiet things down. But after taking another look, I see that they are more than that. I wouldn't of thought about that on any other day.
Sorry,

Quoted 7 lines

Quoted 1 line
-- Steve
Methinks he still is kidding. We have "quiet" as a parameter now to quiet things down on a boot. Now if he would just get rid of the annoying...
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Quoted 1 line
Loading Linux... Uncompressing kernel...
He'd have something.

I suppose this is intended for embedded builds for devices with no means whatsoever to send kernel log anywhere humanly visible. --
vda

Matt Mackall

author

2005-04-01 21:54 UTC #7 lore raw

In reply to Steven Rostedt

Quoted 18 lines · Steven Rostedt

Quoted 17 lines · Matt Mackall
Quoted 15 lines · Andrew Morton
Quoted 10 lines · Matt Mackall
This patch tidies up those annoying kernel messages. A typical kernel
boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.
heh. Please take a look at
http://www.uwsg.iu.edu/hypermail/linux/kernel/0004.2/0709.html, see if Graham did anything which you missed.

Quoted 7 lines

Quoted 4 lines
He's got a bunch of stuff that's not strictly related in there and stuff I've already dealt with (vprintk and the like) and stuff that's still forthcoming (panic tweaks, etc.). I also leave in all the APIs like dmesg, they just no longer do anything.
Looking at your other patches, I'm assuming that this is just another April 1st type of patch. Is it?

Both this and the previous one are in active use by various embedded systems folks and I hope to get them integrated into mainline. Comments welcome.

Signature · 1 line

Mathematics is the supreme nostalgia of our time.

Jan-Benedict Glaw

2005-04-01 20:31 UTC #8 lore raw

In reply to Matt Mackall

On Fri, 2005-04-01 12:08:51 -0800, Matt Mackall <[email protected]> wrote in message <[email protected]>:

Quoted 8 lines

This patch tidies up those annoying kernel messages. A typical kernel boot now looks like this:
Loading Linux... Uncompressing kernel...
#
See? Much nicer. This patch saves about 375k on my laptop config and nearly 100k on minimal configs.

Please also notice these space-savings in the Kconfig help text.

MfG, JBG

Signature · 4 lines

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