[PATCH] clean up kernel messages

[PATCH] clean up kernel messages

[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.

Signed-off-by: Matt Mackall <mpm@selenic.com>

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);
 
+#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);
 
Index: af/init/Kconfig
===================================================================
--- af.orig/init/Kconfig	2005-04-01 00:40:27.000000000 -0800
+++ af/init/Kconfig	2005-04-01 11:02:18.000000000 -0800
@@ -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
Index: af/kernel/printk.c
===================================================================
--- af.orig/kernel/printk.c	2005-04-01 00:32:18.000000000 -0800
+++ af/kernel/printk.c	2005-04-01 10:30:30.000000000 -0800
@@ -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.
  *
Index: af/arch/i386/kernel/head.S
===================================================================
--- af.orig/arch/i386/kernel/head.S	2005-03-02 22:51:03.000000000 -0800
+++ af/arch/i386/kernel/head.S	2005-04-01 10:30:30.000000000 -0800
@@ -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
 
 /*


-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCH] clean up kernel messages

[Andrew Morton]

Matt Mackall <mpm@selenic.com> wrote:
>
> 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.

> 
>  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);
>   
>  +#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.

Re: [PATCH] clean up kernel messages

[Jan-Benedict Glaw]

[-- Attachment #1: Type: text/plain, Size: 798 bytes --]

On Fri, 2005-04-01 12:08:51 -0800, Matt Mackall <mpm@selenic.com>
wrote in message <20050401200851.GG15453@waste.org>:
> 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

-- 
Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481             _ O _
"Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur | Gegen Krieg  _ _ O
 fuer einen Freien Staat voll Freier Bürger" | im Internet! |   im Irak!   O O O
ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [PATCH] clean up kernel messages

[Matt Mackall]

On Fri, Apr 01, 2005 at 12:26:41PM -0800, Andrew Morton wrote:
> Matt Mackall <mpm@selenic.com> wrote:
> >
> > 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.

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.

> 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.
 
> >  +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:
> 
> 	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.

-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCH] clean up kernel messages

[Steven Rostedt]

On Fri, 2005-04-01 at 12:46 -0800, Matt Mackall wrote:
> On Fri, Apr 01, 2005 at 12:26:41PM -0800, Andrew Morton wrote:
> > Matt Mackall <mpm@selenic.com> wrote:
> > >
> > > 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.
> 
> 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

Re: [PATCH] clean up kernel messages

[Steven Rostedt]

On Fri, 2005-04-01 at 16:18 -0500, Steven Rostedt wrote:
> On Fri, 2005-04-01 at 12:46 -0800, Matt Mackall wrote:
> > On Fri, Apr 01, 2005 at 12:26:41PM -0800, Andrew Morton wrote:
> > > Matt Mackall <mpm@selenic.com> wrote:
> > > >
> > > > 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.
> > 
> > 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

Re: [PATCH] clean up kernel messages

[Matt Mackall]

On Fri, Apr 01, 2005 at 04:18:42PM -0500, Steven Rostedt wrote:
> On Fri, 2005-04-01 at 12:46 -0800, Matt Mackall wrote:
> > On Fri, Apr 01, 2005 at 12:26:41PM -0800, Andrew Morton wrote:
> > > Matt Mackall <mpm@selenic.com> wrote:
> > > >
> > > > 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.
> > 
> > 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.

-- 
Mathematics is the supreme nostalgia of our time.

Re: [PATCH] clean up kernel messages

[Richard B. Johnson]

On Fri, 1 Apr 2005, Steven Rostedt wrote:

> On Fri, 2005-04-01 at 16:18 -0500, Steven Rostedt wrote:
>> On Fri, 2005-04-01 at 12:46 -0800, Matt Mackall wrote:
>>> On Fri, Apr 01, 2005 at 12:26:41PM -0800, Andrew Morton wrote:
>>>> Matt Mackall <mpm@selenic.com> wrote:
>>>>>
>>>>> 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.
>>>
>>> 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

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...
>>>>>  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.

Re: [PATCH] clean up kernel messages

[Denis Vlasenko]

On Saturday 02 April 2005 01:08, Richard B. Johnson wrote:
> >> 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
> 
> 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...
> >>>>>  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