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 <Stefani@Seibold.net>
+ */
+
+#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
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