Messages in this thread Patch in this message | | | Date | Wed, 10 Apr 2002 17:38:58 +0200 | From | Jan-Benedict Glaw <> | Subject | Re: Reducing root filesystem |
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On Wed, 2002-04-10 19:38:09 +0530, Amol Kumar Lad <amolk@ishoni.com> wrote in message <7CFD7CA8510CD6118F950002A519EA3001067D06@leonoid.in.ishoni.com>: > Hi, > I am porting Linux to an embedded system. Currently my rootfilesystem is > around 2.5 MB (after keeping it to minimal and adding tools like busybox). I > want to furthur reduce it to say maximum of 1.5 MB. > Please suggest some link/references where I can find the details to optimise > my root filesystem
I really can't help you with the root filesystem, but you can do sth like this:
diff -Nur test-remove-me/linux-2.2.19-clean/Documentation/Configure.help linux-schlecker-2.2.19/Documentation/Configure.help --- test-remove-me/linux-2.2.19-clean/Documentation/Configure.help Sun Mar 25 18:37:29 2001 +++ linux-schlecker-2.2.19/Documentation/Configure.help Mon Nov 5 12:42:46 2001 @@ -4942,6 +4942,14 @@ important data. This is primarily of use to people trying to debug the middle and upper layers of the SCSI subsystem. If unsure, say N. +Smaller kernel by omitting most messages +CONFIG_NO_PRINTK + Enabling this option will result in a smaller kernel by removing + most text strings. This is only useful for emdedded systems where + you've got to live with <= 4MB of RAM. I386-only for now... + + If unsure, say no. + Fibre Channel support CONFIG_FC4 This is an experimental support for storage arrays connected to @@ -210,5 +221,6 @@ #bool 'Debug kmalloc/kfree' CONFIG_DEBUG_MALLOC bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ +bool 'Eleminate *most* printk()s' CONFIG_NO_PRINTK endmenu diff -Nur test-remove-me/linux-2.2.19-clean/arch/i386/kernel/head.S linux-schlecker-2.2.19/arch/i386/kernel/head.S --- test-remove-me/linux-2.2.19-clean/arch/i386/kernel/head.S Sun Mar 25 18:31:45 2001 +++ linux-schlecker-2.2.19/arch/i386/kernel/head.S Fri Nov 2 11:21:42 2001 @@ -315,7 +315,7 @@ movl %ax,%ds movl %ax,%es pushl $int_msg - call SYMBOL_NAME(printk) + call SYMBOL_NAME(real_printk) popl %eax popl %ds popl %es diff -Nur test-remove-me/linux-2.2.19-clean/include/asm-i386/system.h linux-schlecker-2.2.19/include/asm-i386/system.h --- test-remove-me/linux-2.2.19-clean/include/asm-i386/system.h Sun Mar 25 18:31:05 2001 +++ linux-schlecker-2.2.19/include/asm-i386/system.h Mon Dec 17 14:32:03 2001 @@ -135,21 +135,15 @@ switch (size) { case 1: __asm__("xchgb %b0,%1" - :"=q" (x) - :"m" (*__xg(ptr)), "0" (x) - :"memory"); + :"+q" (x),"=m" (*__xg(ptr))); break; case 2: __asm__("xchgw %w0,%1" - :"=r" (x) - :"m" (*__xg(ptr)), "0" (x) - :"memory"); + :"+r" (x),"=m" (*__xg(ptr))); break; case 4: __asm__("xchgl %0,%1" - :"=r" (x) - :"m" (*__xg(ptr)), "0" (x) - :"memory"); + :"+r" (x), "=m" (*__xg(ptr))); break; } return x; diff -Nur test-remove-me/linux-2.2.19-clean/include/linux/kernel.h linux-schlecker-2.2.19/include/linux/kernel.h --- test-remove-me/linux-2.2.19-clean/include/linux/kernel.h Sun Mar 25 18:31:03 2001 +++ linux-schlecker-2.2.19/include/linux/kernel.h Fri Dec 14 14:53:14 2001 @@ -9,6 +9,7 @@ #include <stdarg.h> #include <linux/linkage.h> +#include <linux/config.h> /* Optimization barrier */ /* The "volatile" is due to gcc bugs */ @@ -54,8 +55,16 @@ extern int session_of_pgrp(int pgrp); -asmlinkage int printk(const char * fmt, ...) +asmlinkage int real_printk(const char * fmt, ...) __attribute__ ((format (printf, 1, 2))); + +#ifdef CONFIG_NO_PRINTK +# define printk(format, arg...) do {} while(0) +#else +# define printk(format, arg...) real_printk(format, ## arg) +#endif /* CONFIG_NO_PRINTK */ + +#define oops_printk(format, arg...) real_printk(format, ## arg) #if DEBUG #define pr_debug(fmt,arg...) \ diff -Nur test-remove-me/linux-2.2.19-clean/kernel/ksyms.c linux-schlecker-2.2.19/kernel/ksyms.c --- test-remove-me/linux-2.2.19-clean/kernel/ksyms.c Sun Mar 25 18:31:02 2001 +++ linux-schlecker-2.2.19/kernel/ksyms.c Fri Dec 14 15:24:52 2001 @@ -357,7 +357,7 @@ /* misc */ EXPORT_SYMBOL(panic); -EXPORT_SYMBOL(printk); +EXPORT_SYMBOL(real_printk); EXPORT_SYMBOL(sprintf); EXPORT_SYMBOL(vsprintf); EXPORT_SYMBOL(kdevname); diff -Nur test-remove-me/linux-2.2.19-clean/kernel/printk.c linux-schlecker-2.2.19/kernel/printk.c --- test-remove-me/linux-2.2.19-clean/kernel/printk.c Sun Mar 25 18:31:02 2001 +++ linux-schlecker-2.2.19/kernel/printk.c Fri Dec 14 14:52:50 2001 @@ -249,7 +249,7 @@ return do_syslog(type, buf, len); } -asmlinkage int printk(const char *fmt, ...) +asmlinkage int real_printk(const char *fmt, ...) { va_list args; int i;
This is for i386, but it can be implemented like this for other architectures. Please note:
- The patch to system.h is only neccessary because gcc will magically miscompile the code if there's no printk() resulting (at least) in a broken DMA (de)registering functions rendering the floppy.o module useless. Maybe you don't need this patch. It was _not_ developed by me but send by Momchil Velikov <velco@fadata.bg>. - In 2.4.x, EXPORT_SYMBOL((real)printk) is not in kernel/ksyms.c, but in kernel/printk.c - BigFatWarning: It shouldn't be, but there might be code fragments that do more than only printing in a printk call (like 'printk(KERN_ERR "%d\n", a=func(a))') Things like this _will_ break!!!
MfG, JBG
-- Jan-Benedict Glaw . jbglaw@lug-owl.de . +49-172-7608481 -- New APT-Proxy written in shell script -- http://lug-owl.de/~jbglaw/software/ap2/ [unhandled content-type:application/pgp-signature] | |