1、Linux 内核裁剪的自动化方法Linux 内核裁剪的自动化方法随着广泛地获得使用并被移植到不同的平台，Linux 内核源代码正在越来越大，比如, Linux 2.6.28 中， 文件数有 25282 个，大小有 350M。 对于某一个平台，真正需要的的文件其实不到 10%, 为了提高研发效率，我们应当删除或者暂时删除那些永远也不会用到的文件， 比如，可以使内核的文件数缩减到 5000， 从而节约拷贝、查找等的时间，提高研发效率。本文提出一种高效、干净的进行内核裁剪的办法。以往，我们是通过手工删除某些目录来完成这个任务的。 手工删除的缺点有：1.花时间，每次裁剪都要花 1 2 天， 才能将文件
2、数目删除到 5000 以下。2.不够干净。 内核代码的 Makefile 以及 Kconfig 配置文件彼此的依赖性比较大， 即使某个目录下的功能不被使用，直接删除也会导致编译出错， 从而， 不得不修改相应的 Makefile 以及 Kconfig 才能使编译通过。 这留下一下隐患。3.恢复困难。 根据 2）的描述，在我们对外发布完整版本而需要将以前删除、修改的文件复原时，需要使用比较工具，仔细地比对，才能完整恢复， 这也非常花时间。在经历了手工操作的痛苦之后，我们提出了一种自动化的方法。具体为：1.只删除文件，不删除目录，保留 Makefile 及 Kconfig2.使用时，只需要填充一个配
3、置表，其中，可以指定：1.删除某个文件， 比如：drivers/macintosh/adbhid.c2.删除某个目录下的匹配文件, 比如：include/asm-arm/hardware/*.h3.删除某个目录及其子目录下的匹配文件，比如：drivers/block/#.c4.删除某个目录及其子目录下的适合删除文件, 比如：arch/alpha/#3.脚本会根据配置表，将相关的文件移动到一备份目录，并保持原有的目录结构4.需要恢复时，只需要将备份目录下的文件拷贝到原来的目录，既可。优点如下：1.配置文件一次指定，可反复使用， 对同一内核，不需要更改就可以再次运行。对不同内核，只要稍作修改(内核
4、的目录结构不怎么变化)，既可复用。2.配置文件指定后，裁剪及备份内核的操作可以在几秒内完成，大大提高的效率。3.由于我们只删除 *.c, *.h, *.txt 等文件，而不删除编译相关的配置文件，裁剪后的内核特别干净，不会影响编译。打外部 patch 也特别容易。4.需要对外发布版本时，可以直接运行 restore.sh 脚本，瞬间完成。5.由于操作的可反复性，我们可以不断优化裁剪列表，得到最小内核。最大程度地提高研发效率。以下为例子配置文件：# README #here to specify which files(unused in your project) to move#you ca
5、n specify a relative directory with file name followed#you can specify # *.c to mean all c files below the dir # #.c to mean all c files below the dir and subdir# # to mean all files of known type below the dir and subdir# # Example:# drivers/macintosh/adbhid.c# drivers/dio/*.c# drivers/block/#.c# d
6、rivers/dio/#*kernel version: 2.6.25# arch/#arch/alpha/#arch/avr32/#arch/blackfin/#arch/cris/#arch/frv/#arch/h8300/#arch/ia64/#arch/m32r/#arch/m68k/#arch/m68knommu/#arch/mips/#arch/mn10300/#arch/parisc/#arch/powerpc/#arch/ppc/#arch/s390/#arch/sh/#arch/sparc/#arch/sparc64/#arch/v850/#arch/x86/#arch/xt
7、ensa/# arch/arm#arch/arm/mach-s3c2442/#arch/arm/mach-imx/#arch/arm/mach-s3c2440/#arch/arm/mach-omap2/#arch/arm/mach-clps711x/#arch/arm/mach-s3c2443/#arch/arm/plat-iop/#arch/arm/mach-davinci/#arch/arm/mach-ixp2000/#arch/arm/mach-iop13xx/#arch/arm/mach-integrator/#arch/arm/mach-iop33x/#arch/arm/plat-s
8、3c24xx/#arch/arm/plat-s3c/#arch/arm/plat-omap/#arch/arm/mach-sa1100/#arch/arm/mach-omap1/#arch/arm/mach-aaec2000/#arch/arm/mach-ixp23xx/#arch/arm/mach-mx3/#arch/arm/mach-l7200/#arch/arm/mach-ixp4xx/#arch/arm/mach-at91/#arch/arm/mach-clps7500/#arch/arm/mach-rpc/#arch/arm/mach-s3c2400/#arch/arm/plat-m
9、xc/#arch/arm/mach-iop32x/#arch/arm/mach-footbridge/#arch/arm/mach-h720x/#arch/arm/mach-ep93xx/#arch/arm/mach-ebsa110/#arch/arm/mach-realview/#arch/arm/mach-s3c2412/#arch/arm/mach-ns9xxx/#arch/arm/mach-orion/#arch/arm/mach-shark/#arch/arm/mach-netx/#arch/arm/mach-pnx4008/#arch/arm/mach-s3c2410/#arch/
10、arm/mach-lh7a40x/#arch/arm/mach-ks8695/#arch/arm/mach-versatile/#arch/arm/mach-msm/# Documetation#Documentation/# drivers #drivers/acorn/#drivers/acpi/#drivers/amba/#drivers/ata/#drivers/atm/#drivers/auxdisplay/#drivers/cdrom/#drivers/dca/#drivers/dio/#drivers/edac/#drivers/eisa/#drivers/ide/#driver
11、s/ieee1394/#drivers/infiniband/#drivers/isdn/#drivers/macintosh/#drivers/mca/#drivers/md/#drivers/memstick/#drivers/nubus/#drivers/of/#drivers/parisc/#drivers/parport/#drivers/pci/#drivers/pcmcia/#drivers/pnp/#drivers/ps3/#drivers/rapidio/#drivers/s390/#drivers/sbus/#drivers/sh/#drivers/sn/#drivers/
12、ssb/#drivers/telephony/#drivers/thermal/#drivers/xen/#drivers/zorro/# drivers/char #drivers/char/agp/#drivers/char/mwave/#drivers/char/pcmcia/#drivers/char/rio/#drivers/char/drm/# drivers/net #drivers/net/appletalk/#drivers/net/ibm_emac/#drivers/net/ibm_newemac/#drivers/net/ixp2000/#drivers/net/pcmc
13、ia/#drivers/net/tokenring/# drivers/scsi #drivers/scsi/aic7xxx/#drivers/scsi/aic7xxx_old/#drivers/scsi/aic94xx/#drivers/scsi/lpfc/#drivers/scsi/pcmcia/#drivers/scsi/qla2xxx/#drivers/scsi/qla4xxx/#drivers/scsi/sym53c8xx_2/# drivers/media #drivers/media/dvb/# drivers/media/video #drivers/media/video/b
14、t8xx/#drivers/media/video/cpia2/#drivers/media/video/cx23885/#drivers/media/video/cx25840/#drivers/media/video/em28xx/#drivers/media/video/ivtv/#drivers/media/video/pvrusb2/#drivers/media/video/saa7134/#drivers/media/video/sn9c102/#drivers/media/video/zc0301/# fs #fs/9p/#fs/afs/#fs/adfs/#fs/affs/#fs
15、/bfs/#fs/befs/#fs/coda/#fs/dlm/#fs/freevxfs/#fs/gfs2/#fs/hfs/#fs/hfsplus/#fs/hpfs/#fs/isofs/#fs/jbd/#fs/jbd2/#fs/jfs/#fs/minix/#fs/ntfs/#fs/ncpfs/#fs/ocfs2/#fs/qnx4/#fs/udf/#fs/ufs/#fs/xfs/# include #include/acpi/#include/asm-alpha/#include/asm-avr32/#include/asm-blackfin/#include/asm-cris/#include/
16、asm-frv/#include/asm-h8300/#include/asm-ia64/#include/asm-m32r/#include/asm-m68k/#include/asm-m68knommu/#include/asm-mips/#include/asm-mn10300/#include/asm-parisc/#include/asm-powerpc/#include/asm-ppc/#include/asm-s390/#include/asm-sh/#include/asm-sparc/#include/asm-sparc64/#include/asm-um/#include/
17、asm-v850/#include/asm-x86/#include/asm-xtensa/#include/pcmcia/# include/asm-arm #include/asm-arm/arch-ks8695/#include/asm-arm/arch-iop33x/#include/asm-arm/arch-mxc/#include/asm-arm/arch-iop32x/#include/asm-arm/arch-ep93xx/#include/asm-arm/arch-h720x/#include/asm-arm/arch-iop13xx/#include/asm-arm/arc
18、h-ns9xxx/#include/asm-arm/arch-ebsa285/#include/asm-arm/arch-orion/#include/asm-arm/arch-ixp2000/#include/asm-arm/arch-s3c2400/#include/asm-arm/arch-msm/#include/asm-arm/arch-ixp4xx/#include/asm-arm/arch-lh7a40x/#include/asm-arm/arch-ebsa110/#include/asm-arm/arch-netx/#include/asm-arm/arch-imx/#incl
19、ude/asm-arm/arch-ixp23xx/#include/asm-arm/arch-davinci/#include/asm-arm/arch-sa1100/#include/asm-arm/plat-s3c24xx/#include/asm-arm/plat-s3c/#include/asm-arm/arch-l7200/#include/asm-arm/arch-versatile/#include/asm-arm/arch-clps711x/#include/asm-arm/arch-aaec2000/#include/asm-arm/arch-cl7500/#.h inclu
20、de/asm-arm/arch-pnx4008/#include/asm-arm/arch-integrator/#include/asm-arm/arch-at91/#include/asm-arm/arch-shark/#include/asm-arm/arch-rpc/#include/asm-arm/arch-s3c2410/#include/asm-arm/arch-realview/# net/#net/ax25/#net/can/#net/decnet/#net/ipv6/#net/x25/# sound/#sound/aoa/#sound/isa/#sound/mips/#so
21、und/oss/#sound/parisc/#sound/pci/#sound/pcmcia/#sound/ppc/#sound/sh/#sound/sparc/#以下为备份脚本：#! /bin/bash#name: move.sh#function: move unused files from kernel to make size smaller#set -xfunction usage()echo “Usage:“ $0 “filename“echo “ filename is the file that includes files to be deleted“echo “ if n
22、ot provided, filename default to to_delete_files“if $# -ne “1“ ; thenINPUT_FILE=“to_cutoff_files“echo inputfile default to $INPUT_FILEelseif $1 = “-h“ ; thenusageexit 0fiINPUT_FILE=$1fiBASE_ORIG=cd ; pwd/BASE_NEW=cd files; pwd/FILES_LIST=.$INPUT_FILE_detailedrm -f $FILES_LIST#echo “restore files“#cp
23、 -a files/* / 2/dev/null#rm -rf files/* 2 /dev/nullecho “generate detailed file list.“cat $INPUT_FILE | grep -v # | while read LINEdoif ! -z $LINE ; thenif expr index $LINE “#“ != “0“ ; thenDIR_ORIG=$BASE_ORIG$LINEDIR_ORIG=$DIR_ORIG%/*find $DIR_ORIG -name *.h $FILES_LISTfind $DIR_ORIG -name *.c $FIL
24、ES_LISTfind $DIR_ORIG -name *.S $FILES_LISTfind $DIR_ORIG -name *.txt $FILES_LISTfind $DIR_ORIG -name *_defconfig $FILES_LISTelif expr index $LINE “#“ != “0“ ; thenDIR_ORIG=$BASE_ORIG$LINEDIR_ORIG=$DIR_ORIG%/*FILE_EXT=$LINE#*.find $DIR_ORIG -name *.$FILE_EXT $FILES_LISTelif expr index $LINE “*“ != “
25、0“ ; thenDIR_ORIG=$BASE_ORIG$LINEDIR_ORIG=$DIR_ORIG%/*FILE_EXT=$LINE#*.find $DIR_ORIG -name *.$FILE_EXT -maxdepth 1 $FILES_LISTelse echo $BASE_ORIG$LINE $FILES_LISTfifidoneecho “move files.“INPUT_FILE=$FILES_LISTcat $INPUT_FILE 2/dev/null | grep -v # | while read LINEdoif ! $LINE = “ ; thenFILE_ORIG=$LINELINE2=$LINE#$BASE_ORIGFILE_NEW=$BASE_NEW$LINE2DIR_NEW=$FILE_NEW%/*if ! -d $DIR_NEW ; thenmkdir -p $DIR_NEWfiif -f $FILE_ORIG ; then mv -f $FILE_ORIG $DIR_NEWfifidone以下为恢复脚本：#! /bin/bashcp -a files/* /rm -rf files/*
