Re: patch for suppress printk messages

[Tommy Faasen]

Can you show an example what is printed now?

Thanks
----- Original Message -----
From: "Stefani Seibold" <[e-mail]>
To: <[e-mail]>; <[e-mail]>
Cc: <[e-mail]>; <[e-mail]>
Sent: Tuesday, December 04, 2001 5:40 PM
Subject: patch for suppress printk messages

> Hi everybody,
>
> this is my new version for suppressing kernel printk messages. This will
shrink
> the kernel by an average of 10 percent (for example my desktop kernel will
shrink
> about 90K).
> It is usefull on deeply embedded systems with no human interactions and
for rescue
> discs where the diskspace is always to less.
>
> This patch has the following features:
>
> - The macro printk will evalute all parameters, than throw it away and
return 0 as
> result. So it should be do the same from the callers view, like the
original printk
> function, but all arguments will be removed by compiler optimatzion if
possible.
>
> - The macro panic will also evaluate the parameters and throw it away by
compiler
> optimatzion if possible.
>
> - No compiler warnings also on max. compiler warning level.
>
> - Up to 16 arguments will be evaluated. This can be simply extended by
adding
> additional DOARG_xx Macros.
>
> - For backward compatibility the functions printk and panic will be also
implemented and
> exported as functions with no output .
>
> - The name of the config variable is CONFIG_DEBUG_SUPPRESS.
>
> - The option for disabling the printk and panic messages in the menu
kernel
> hacking.
>
> The complexity for the printk and panic macro is still necessary, because
this
> is the only way, to evaluate a macro with variable arguments without
> compiler warnings.
>
> I hope this will it now do in the developer kernel release 2.5, because no
side
> effects should be now expect.
>
> Thanks,
> Stefani Seibold
>
> -----patch for suppress printk messages against 2.4.16 -----
>
> diff -u --recursive --new-file linux.orig/Documentation/Configure.help
linux.new/Documentation/Configure.help
> --- /home/stefani/soft/kernel/linux/Documentation/Configure.help Thu Nov
22 19:52:44 2001
> +++ linux/Documentation/Configure.help Tue Dec 4 16:40:24 2001
> @@ -23590,11 +23590,19 @@
> best used in conjunction with the NMI watchdog so that spinlock
> deadlocks are also debuggable.
>
> -Verbose BUG() reporting (adds 70K)
> -CONFIG_DEBUG_BUGVERBOSE
> - Say Y here to make BUG() panics output the file name and line number
> - of the BUG call as well as the EIP and oops trace. This aids
> - debugging but costs about 70-100K of memory.
> +Kernel debug output
> +CONFIG_DEBUG_DEFAULT
> + Which this option, you can specify the kernel verbosity.
> +
> + - default is the normal setting for most linux boxes (Server, Desktop)
> + - verbose will aids debugging and is the recommended setting for kernel
> + hackers. Say Y here to make BUG() panics output the file name and line
> + number of the BUG call as well as the EIP and oops trace.
> + (this options adds 70K-100K to your kernel)
> + - suppress wil be useful for deeply embedded system where nobody will
> + see any kernel output
> + (this option will save a lot of rom and ram space >70K)
> +
>
> Include kgdb kernel debugger
> CONFIG_KGDB
> diff -u --recursive --new-file linux.orig/kernel/panic.c
linux.new/kernel/panic.c
> --- /home/stefani/soft/kernel/linux/kernel/panic.c Tue Dec 4 16:10:36 2001
> +++ linux/kernel/panic.c Tue Dec 4 14:10:45 2001
> @@ -8,14 +8,17 @@
> * This function is used through-out the kernel (including mm and fs)
> * to indicate a major problem.
> */
> -#include <linux/config.h>
> #include <linux/sched.h>
> #include <linux/delay.h>
> #include <linux/reboot.h>
> #include <linux/notifier.h>
> -#include <linux/init.h>
> #include <linux/sysrq.h>
> -#include <linux/interrupt.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h> /* For in_interrupt() */
> +#include <linux/config.h>
> +
> +#include <asm/uaccess.h>
>
> asmlinkage void sys_sync(void); /* it's really int */
>
> @@ -31,6 +34,12 @@
>
> __setup("panic=", panic_setup);
>
> +#ifdef CONFIG_DEBUG_SUPPRESS
> +#undef panic
> +
> +NORET_TYPE void panic_nomsg(void) __attribute__ ((alias("panic")));
> +#endif
> +
> /**
> * panic - halt the system
> * @fmt: The text string to print
> @@ -43,17 +52,21 @@
>
> NORET_TYPE void panic(const char * fmt, ...)
> {
> - static char buf[1024];
> - va_list args;
> #if defined(CONFIG_ARCH_S390)
> unsigned long caller = (unsigned long) __builtin_return_address(0);
> #endif
> +#ifndef CONFIG_DEBUG_SUPPRESS
> + static char buf[1024];
> + va_list args;
>
> - bust_spinlocks(1);
> va_start(args, fmt);
> vsprintf(buf, fmt, args);
> va_end(args);
> printk(KERN_EMERG "Kernel panic: %s\n",buf);
> +#else
> + (void)(fmt);
> +#endif
> + bust_spinlocks(1);
> if (in_interrupt())
> printk(KERN_EMERG "In interrupt handler - not syncing\n");
> else if (!current->pid)
> @@ -100,7 +113,9 @@
> }
> }
>
> -/**
> +EXPORT_SYMBOL(panic);
> +
> +/*
> * print_tainted - return a string to represent the kernel taint state.
> *
> * The string is overwritten by the next call to print_taint().
> diff -u --recursive --new-file linux.orig/kernel/printk.c
linux.new/kernel/printk.c
> --- /home/stefani/soft/kernel/linux/kernel/printk.c Tue Dec 4 16:10:36
2001
> +++ linux/kernel/printk.c Tue Dec 4 16:07:20 2001
> @@ -371,6 +371,22 @@
> _call_console_drivers(start_print, end, msg_level);
> }
>
> +#ifdef CONFIG_DEBUG_SUPPRESS
> +
> +/*
> + * Disable printk function calls
> + * This is useful for deeply embedded system where nobody will see the
> + * kernel output
> + * Stefani Seibold <[e-mail]>
> + */
> +
> +#undef printk
> +asmlinkage int printk(const char *fmt, ...)
> +{
> + (void)(fmt);
> + return 0;
> +}
> +#else
> static void emit_log_char(char c)
> {
> LOG_BUF(log_end) = c;
> @@ -456,6 +472,8 @@
> }
> return printed_len;
> }
> +#endif
> +
> EXPORT_SYMBOL(printk);
>
> /**
> diff -u --recursive --new-file linux.orig/kernel/ksyms.c
linux.new/kernel/ksyms.c
> --- /home/stefani/soft/kernel/linux/kernel/ksyms.c Tue Dec 4 16:10:36 2001
> +++ linux/kernel/ksyms.c Tue Dec 4 14:03:53 2001
> @@ -449,7 +449,6 @@
> EXPORT_SYMBOL(nr_running);
>
> /* misc */
> -EXPORT_SYMBOL(panic);
> EXPORT_SYMBOL(sprintf);
> EXPORT_SYMBOL(snprintf);
> EXPORT_SYMBOL(sscanf);
> diff -u --recursive --new-file linux.orig/kernel/Makefile
linux.new/kernel/Makefile
> --- /home/stefani/soft/kernel/linux/kernel/Makefile Tue Dec 4 16:10:36
2001
> +++ linux/kernel/Makefile Tue Dec 4 13:52:24 2001
> @@ -9,7 +9,7 @@
>
> O_TARGET := kernel.o
>
> -export-objs = signal.o sys.o kmod.o context.o ksyms.o pm.o exec_domain.o
printk.o
> +export-objs = signal.o sys.o kmod.o context.o ksyms.o pm.o exec_domain.o
printk.o panic.o
>
> obj-y = sched.o dma.o fork.o exec_domain.o panic.o printk.o \
> module.o exit.o itimer.o info.o time.o softirq.o resource.o \
> diff -u --recursive --new-file linux.orig/include/linux/kernel.h
linux.new/include/linux/kernel.h
> --- /home/stefani/soft/kernel/linux/include/linux/kernel.h Tue Dec 4
16:10:36 2001
> +++ linux/include/linux/kernel.h Tue Dec 4 16:31:23 2001
> @@ -49,8 +49,16 @@
> struct completion;
>
> extern struct notifier_block *panic_notifier_list;
> +
> NORET_TYPE void panic(const char * fmt, ...)
> __attribute__ ((NORET_AND format (printf, 1, 2)));
> +
> +#ifdef CONFIG_DEBUG_SUPPRESS
> +#define panic(format ,args...) (DOARG_0(format, ## args
,0),panic_nomsg())
> +
> +NORET_TYPE void panic_nomsg(void) ATTRIB_NORET;
> +#endif
> +
> asmlinkage NORET_TYPE void do_exit(long error_code)
> ATTRIB_NORET;
> NORET_TYPE void complete_and_exit(struct completion *, long)
> @@ -79,8 +87,35 @@
>
> extern int session_of_pgrp(int pgrp);
>
> +#ifdef CONFIG_DEBUG_SUPPRESS
> +static __inline__ int printk_nomsg(void)
> +{
> + return 0;
> +}
> +
> +#define DOARG_15(arg, args...) ((void)(arg))
> +#define DOARG_14(arg, args...) (DOARG_15(args,0),((void)(arg)))
> +#define DOARG_13(arg, args...) (DOARG_14(args,0),((void)(arg)))
> +#define DOARG_12(arg, args...) (DOARG_13(args,0),((void)(arg)))
> +#define DOARG_11(arg, args...) (DOARG_12(args,0),((void)(arg)))
> +#define DOARG_10(arg, args...) (DOARG_11(args,0),((void)(arg)))
> +#define DOARG_9(arg, args...) (DOARG_10(args,0),((void)(arg)))
> +#define DOARG_8(arg, args...) (DOARG_9(args,0),((void)(arg)))
> +#define DOARG_7(arg, args...) (DOARG_8(args,0),((void)(arg)))
> +#define DOARG_6(arg, args...) (DOARG_7(args,0),((void)(arg)))
> +#define DOARG_5(arg, args...) (DOARG_6(args,0),((void)(arg)))
> +#define DOARG_4(arg, args...) (DOARG_5(args,0),((void)(arg)))
> +#define DOARG_3(arg, args...) (DOARG_5(args,0),((void)(arg)))
> +#define DOARG_2(arg, args...) (DOARG_3(args,0),((void)(arg)))
> +#define DOARG_1(arg, args...) (DOARG_2(args,0),((void)(arg)))
> +#define DOARG_0(arg, args...) (DOARG_1(args,0),((void)(arg)))
> +
> +#define printk(format ,args...) (DOARG_0(format, ## args
,0),printk_nomsg())
> +#else
> +
> asmlinkage int printk(const char * fmt, ...)
> __attribute__ ((format (printf, 1, 2)));
> +#endif
>
> extern int console_loglevel;
>
> diff -u --recursive --new-file linux.orig/include/asm-i386/spinlock.h
linux.new/include/asm-i386/spinlock.h
> --- /home/stefani/soft/kernel/linux/include/asm-i386/spinlock.h Tue Dec 4
16:10:36 2001
> +++ linux/include/asm-i386/spinlock.h Tue Dec 4 14:12:00 2001
> @@ -6,8 +6,12 @@
> #include <asm/page.h>
> #include <linux/config.h>
>
> +#ifdef CONFIG_DEBUG_SUPPRESS
> +inline int printk(const char * fmt, ...) { (void)(fmt); }
> +#else
> extern int printk(const char * fmt, ...)
> __attribute__ ((format (printf, 1, 2)));
> +#endif
>
> /* It seems that people are forgetting to
> * initialize their spinlocks properly, tsk tsk.
> diff -u --recursive --new-file linux.orig/arch/i386/kernel/head.S
linux.new/arch/i386/kernel/head.S
> --- /home/stefani/soft/kernel/linux/arch/i386/kernel/head.S Tue Dec 4
16:10:36 2001
> +++ linux/arch/i386/kernel/head.S Tue Dec 4 16:11:19 2001
> @@ -324,6 +324,7 @@
> .long __KERNEL_DS
>
> /* This is the default interrupt "handler" :-) */
> +#ifndef CONFIG_DEBUG_SUPPRESS
> int_msg:
> .asciz "Unknown interrupt\n"
> ALIGN
> @@ -345,6 +346,11 @@
> popl %edx
> popl %ecx
> popl %eax
> +#else
> +ignore_int:
> + ALIGN
> + cld
> +#endif
> iret
>
> /*
> diff -u --recursive --new-file linux.orig/arch/i386/config.in
linux.new/arch/i386/config.in
> --- /home/stefani/soft/kernel/linux/arch/i386/config.in Tue Dec 4 16:10:36
2001
> +++ linux/arch/i386/config.in Tue Dec 4 16:37:02 2001
> @@ -406,7 +406,10 @@
> bool ' Memory mapped I/O debugging' CONFIG_DEBUG_IOVIRT
> bool ' Magic SysRq key' CONFIG_MAGIC_SYSRQ
> bool ' Spinlock debugging' CONFIG_DEBUG_SPINLOCK
> - bool ' Verbose BUG() reporting (adds 70K)' CONFIG_DEBUG_BUGVERBOSE
> + choice 'Kernel debug output' \
> + "default CONFIG_DEBUG_DEFAULT \
> + verbose CONFIG_DEBUG_BUGVERBOSE \
> + suppress CONFIG_DEBUG_SUPPRESS" default
> fi
>
> endmenu
> diff -u --recursive --new-file linux.orig/arch/ppc/config.in
linux.new/arch/ppc/config.in
> --- /home/stefani/soft/kernel/linux/arch/ppc/config.in Tue Dec 4 16:10:36
2001
> +++ linux/arch/ppc/config.in Tue Dec 4 14:42:33 2001
> @@ -392,4 +392,8 @@
> bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ
> bool 'Include kgdb kernel debugger' CONFIG_KGDB
> bool 'Include xmon kernel debugger' CONFIG_XMON
> +choice 'Kernel debug output' \
> + "default CONFIG_DEBUG_DEFAULT \
> + verbose CONFIG_DEBUG_BUGVERBOSE \
> + suppress CONFIG_DEBUG_SUPPRESS" default
> endmenu
>