一. 內核啓動流程，據此配置內核(機器ID)
1. 獲取內核源碼 www.kernel.org
https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.4.2.tar.bz2
2. 解壓內核
# tar xjvf linux-3.4.2.tar.bz2
3. 修改頂層Makefile，指定交叉編譯器
ARCH ?= arm
CROSS_COMPILE ?= arm-linux-
4. 使用默認配置編譯內核，可使用如下命令查看內核有哪些默認配置
# find -name “*defconfig”
使用缺省內核配置文件,s3c2410_defconfig 是SMDK2410 的缺省配置文件
# make s3c2410_defconfig
編譯、測試
# make uImage
拷貝uImage到tftpboot目錄
# cp arch/arm/boot/uImage /work/tftpboot/uImage_3.4.2
下載、啓動內核
# tftp 32000000 uImage_3.4.2
# bootm 32000000
結果，啓動後會產生亂碼，原因是bootargs參數並未指定串口波特率，修改bootargs如下即可正常啓動看到輸出
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3
5. 修改晶振頻率
# vim arch/arm/mach-s3c24xx/mach-smdk2440.c
–s3c24xx_init_clocks(16934400);
++s3c24xx_init_clocks(12000000);
編譯、測試
# make s3c2410_defconfig //支持內核較多
# make uImage
# set machid 16a //SMDK2440的機器ID
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3
# tftp 32000000 uImage_3.4.2
# bootm 32000000
可正常輸出內核啓動信息，說明串口工作正常
二. 修改分區, 製作新的文件系統
2.1 修改分區，和我修改後的u-boot-2012.04.01一致，參考友善之臂文檔《Mini2440 Linux移植開發實戰指南.pdf》
0x00000000-0x00060000 : “bootloader”
0x00060000-0x00080000 : “params”
0x00050000-0x00580000 : “kernel”
0x00580000- : “root”
# vim arch/arm/mach-s3c24xx/common-smdk.c
點擊(此處)摺疊或打開
static struct mtd_partition smdk_default_nand_part[] = {
[0] = {
.name = “bootloader”,
.size = SZ_256K + SZ_128K,
.offset = 0,
},
[1] = {
.name = “params”,
.offset = SZ_256K + SZ_128K,
.size = SZ_128K,
},
[2] = {
.name = “kernel”,
.offset = SZ_512K,
.size = 0x00500000,
},
[3] = {
.name = “root”,
.offset = SZ_512K + 0x00500000,
.size = MTDPART_SIZ_FULL,
},
};
編譯、測試
# make uImage
# cp arch/arm/boot/uImage /work/tftpboot/uImage_3.4.2
# setenv bootcmd 'tftp 32000000 uImage_3.4.2;bootm 32000000'
# boot
可看到打印出如下分區信息
點擊(此處)摺疊或打開
List of all partitions:
1f00 384 mtdblock0 (driver?)
1f01 128 mtdblock1 (driver?)
1f02 5120 mtdblock2 (driver?)
1f03 1042944 mtdblock3 (driver?)
燒寫文件系統、測試fs_mini_mdev.yaffs2<該文件系統來自韋東山老師的教程>
# tftp 32000000 fs_mini_mdev.yaffs2
# nand erase.part root
# nand write.yaffs 32000000 0x580000 $filesize
測試
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3
# setenv bootcmd 'tftp 32000000 uImage_3.4.2;bootm 32000000'
# boot
結果：
No filesystem could mount root, tried: ext3 ext2 cramfs vfat msdos iso9660 romfs
測試jffs2
# tftp 32000000 fs_mini_mdev.jffs2
# nand erase.part root
# nand write.jffs2 32000000 580000 $filesize
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3 rootfstype=jffs2
# boot
不能使用
2.2 製作根文件系統
① 編譯安裝busybox
編譯 busybox-1.20.0.tar.bz2
# tar xjvf busybox-1.20.0.tar.bz2
# cd busybox-1.20.0
# make menuconfig
Busybox Settings --->
Build Options --->
() Cross Compiler prefix
填入arm-linux-
保存、退出，執行make
# make
創建文件系統目錄
# cd /work/nfsroot
# mkdir fs_mini_mdev_new
安裝
# make install CONFIG_PREFIX=/work/nfsroot/fs_mini_mdev_new
② 安裝libc庫，使用arm-linux-gcc 4.3.2 中的庫文件
# cd /work/nfsroot/fs_mini_mdev_new
# mkdir lib
# cd lib
# cp /usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/lib/*so* ./ -d
# cd ../
# mkdir usr/lib -p
# cd usr/lib
# cp /usr/local/arm/4.3.2/arm-none-linux-gnueabi/libc/armv4t/usr/lib/*so* ./ -d
③ 構建etc目錄
# cp -rf ../fs_mini_mdev/etc ./
修改inttab
# vim inittab
將s3c2410_serial0改爲console
④ 構建dev目錄
# mkdir dev
# cd dev
# mknod console c 5 1
# mknod null c 1 3
⑤ 創建其他目錄
# mkdir proc tmp mnt sys root
⑥ 製作jffs2根文件系統，參考《嵌入式Linux應用開發完全手冊》
# mkfs.jffs2 -n -s 2048 -e 128KiB -d fs_mini_mdev_new -o fs_mini_mdev_new.jffs2
⑦ 燒寫測試
# cp fs_mini_mdev_new.jffs2 /work/tftpboot
# tftp 32000000 fs_mini_mdev_new.jffs2
# nand erase.part root
# nand write.jffs2 32000000 580000 $filesize
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3 rootfstype=jffs2
# boot
⑧ 結果
Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
出錯、退出
解決方法
配置內核
# make menuconfig
Kernel Features --->
[*] Use the ARM EABI to compile the kernel //選中該項
# make uImage
# cp arch/arm/boot/uImage /work/tftpboot/uImage_3.4.2_eabi
測試
# tftp 32000000 uImage_3.4.2_eabi
# bootm 32000000
可正常啓動
Please press Enter to activate this console.
/ #
三. 移植YAFFS文件系統
獲取yaffs2源碼
# git clone git://www.aleph1.co.uk/yaffs2
給內核打yaffs2補丁，參考readme
# cd yaffs2
# ./patch-ker.sh c m /work/kernel/linux-3.4.2
配置內核使其支持yaffs2文件系統
# make menuconfig
File systems —>
[*]Miscellaneous filesystems —>
<*> yaffs2 file system support
# make uImage
製作yaffs2根文件系統
# mkyaffs2image fs_mini_mdev_new fs_mini_mdev_new.yaffs2
# mv fs_mini_mdev_new.yaffs2 /work/tftpboot/
# cp arch/arm/boot/uImage /work/tftpboot/uImage_3.4.2_yaffs2
燒寫Yaffs2文件系統
# tftp 32000000 fs_mini_mdev_new.yaffs2
# nand erase.part root //擦除root分區
# nand write.yaffs 32000000 580000 $filesize //親測用nand write.jffs2會出錯，找不到init進程
啓動內核
# tftp 32000000 uImage_3.4.2_yaffs2
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3
# bootm 32000000
可修改bootcmd參數便捷啓動
# setenv bootcmd ‘tftp 32000000 uImage_3.4.2_yaffs2;bootm 32000000’
四. 裁剪內核
查看現在內核大小
# ls arch/arm/boot/uImage -l
-rw-r–r– 1 root root 2486104 Dec 30 22:41 arch/arm/boot/uImage
# make menuconfig //去掉不需要的項
a. 去掉不需要支持的單板
System Type —>
SAMSUNG S3C24XX SoCs Support —>
* S3C24XX SoCs *
[ ] SAMSUNG S3C2410
[ ] SAMSUNG S3C2412
[ ] SAMSUNG S3C2416/S3C2450
[*] SAMSUNG S3C2440
[ ] SAMSUNG S3C2442
[ ] SAMSUNG S3C2443
* S3C2440 Boards *
[ ] Simtec Electronics ANUBIS
[ ] Avantech AT2440EVB development board
[*] MINI2440 development board
[ ] NexVision NEXCODER 2440 Light Board
[ ] Simtec IM2440D20 (OSIRIS) module
[ ] HP iPAQ rx3715
[*] SMDK2440
[*] SMDK2440 with S3C2440 CPU module
b. 裁剪對文件系統的支持
File systems --->
< > Second extended fs support //去掉對ext2的支持
< > Ext3 journalling file system support //去掉對ext3的支持
DOS/FAT/NT Filesystems ---> //不作修改，對U盤的支持需要
c. 裁剪對驅動的支持
Device Drivers --->
Input device support --->
[ ] Provide legacy /dev/psaux device //delete
[ ] Mice ---> //delete
[ ] Keyboards ---> //delete
d.繼續裁剪
File systems --->
CD-ROM/DVD Filesystems --->
< > ISO 9660 CDROM file system support //去掉對光盤的支持
[*] Miscellaneous filesystems --->
< > Compressed ROM file system support (cramfs) //delete
[ ] Include support for ZLIB compressed file systems //delete
< > ROM file system support //delete
Device Drivers --->
Input device support --->
[*] Touchscreens --->
<*> Samsung S3C2410/generic touchscreen input driver //配置上該項
< > USB Touchscreen Driver //delete
Device Drivers --->
<*> Sound card support --->
<*> Advanced Linux Sound Architecture --->
[ ] USB sound devices ---> //delete
Device Drivers --->
[*] USB support --->
[ ] The shared table of common (or usual) storage devices //delete
保存、退出編譯內核
# make uImage
# cp arch/arm/boot/uImage /work/tftpboot/uImage_3.4.2_sm
燒寫內核
# tftp 30000000 uImage_3.4.2_sm
# nand erase.part kernel; nand write 30000000 kernel
啓動內核
# set bootcmd 'nand read 30000000 kernel;bootm 30000000'
# set bootargs console=ttySAC0,115200 root=/dev/mtdblock3
# set machid 16a
# save
# boot