1.1. Initramfs的制作和移植
1.1.1. 對根文件系統進行修改
根文件系統制作可以參考這篇文檔
由於制作initramfs文件系統啟動時會在根文件系統中執行第一個init程序，它對uboot傳過來的參數init=/linuxrc不予理睬，所以需要在制作的根文件系統裡的根目錄加入init程序，否則無法啟動。init程序和linuxrc程序一樣都是符號鏈接文件，它們都是指向/bin/busybox程序。
[lingyun@localhost rootfs]$ ll
total 60
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 apps
drwxr-xr-x 2 lingyun trainning 4096 Apr 26 15:16 bin
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 data
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:51 dev
drwxr-xr-x 4 lingyun trainning 4096 Apr 26 14:16 etc
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 info
drwxr-xr-x 3 lingyun trainning 4096 Apr 25 21:17 lib
lrwxrwxrwx 1 root root 11 Apr 26 15:16 linuxrc -> bin/busybox
drwxr-xr-x 6 lingyun trainning 4096 Apr 25 20:15 mnt
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 proc
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 root
drwxr-xr-x 2 lingyun trainning 4096 Apr 26 15:16 sbin
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 sys
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 tmp
drwxr-xr-x 6 lingyun trainning 4096 Apr 25 20:15 usr
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:57 var
[lingyun@localhost rootfs]$ ln -s bin/busybox init
[lingyun@localhost rootfs]$ ll
total 60
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 apps
drwxr-xr-x 2 lingyun trainning 4096 Apr 26 15:16 bin
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 data
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:51 dev
drwxr-xr-x 4 lingyun trainning 4096 Apr 26 14:16 etc
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 info
lrwxrwxrwx 1 lingyun trainning 11 Apr 27 21:19 init -> bin/busybox
drwxr-xr-x 3 lingyun trainning 4096 Apr 25 21:17 lib
lrwxrwxrwx 1 root root 11 Apr 26 15:16 linuxrc -> bin/busybox
drwxr-xr-x 6 lingyun trainning 4096 Apr 25 20:15 mnt
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 proc
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 root
drwxr-xr-x 2 lingyun trainning 4096 Apr 26 15:16 sbin
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 sys
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:15 tmp
drwxr-xr-x 6 lingyun trainning 4096 Apr 25 20:15 usr
drwxr-xr-x 2 lingyun trainning 4096 Apr 25 20:57 var
[lingyun@localhost rootfs]$
1.1.2. 添加內核支持
[lingyun@localhost kernel]$ ls
build.sh linux-3.0 linux-3.0.tar.bz2 patch
[lingyun@localhost kernel]$ cd linux-3.0
[lingyun@localhost linux-3.0]$ vt100
[lingyun@localhost linux-3.0]$ make menuconfig
。 。 。 。 。 。
General setup --->
[*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
(/opt/rootfs) Initramfs source file(s) #輸入根文件系統的所在目錄
。 。 。 。 。 。
[lingyun@localhost linux-3.0]$ ls
arch crypto fs Kbuild linuxrom-s3c2440.bin modules.builtin README security usr
block Documentation include Kconfig MAINTAINERS modules.order REPORTING-BUGS sound virt
COPYING drivers init kernel Makefile Module.symvers samples System.map vmlinux
CREDITS firmware ipc lib mm net scripts tools vmlinux.o
[lingyun@localhost linux-3.0]$ du -h linuxrom-s3c2440.bin
6.9M /tftp/linuxrom-s3c2440.bin
[lingyun@localhost linux-3.0]$ mv linuxrom-s3c2440.bin /tftp/
1.1.3. 制作映像文件
因為文件系統和內核是集成在一起的，所以不需要制作文件系統映像
1.1.4. 添加uboot支持
下面對uboot進行修改。
[ s3c2440@guowenxue ]# pri
bbl=nand erase 0 100000;tftp 30008000 u-boot-$cpu.bin;nand write 30008000 0 $filesize
norbbl=erase bank 1;tftp 30008000 u-boot-$cpu.bin;cp.b 30008000 0 $filesize
bkr=tftp 30008000 uImage-$cpu.gz;nand erase 100000 400000;nand write 30008000 100000 $filesize
bootcmd_rootfs=nand read 30008000 100000 400000;bootm 30008000
tpb=tftp 30008000 uImage-$cpu.gz;tftp 30800000 ramdisk-$cpu.gz;bootm 30008000
mtdids=nand0=nand0
mtdparts=mtdparts=nand0:1M@0x0(u-boot),5M@0x100000(kernel),10M@0x600000(ramdisk),10M@0x1000000(cramfs),20M@0x1a00000(yaffs2),20M@0x2e00000(ubifs),-(users)
bootdelay=1
baudrate=115200
ethaddr=08:00:3e:26:0a:6b
ethact=dm9000
bcramfs=tftp 30800000 rootfs.cramfs;nand erase f00000 600000;nand write 30800000 f00000 600000
bjffs2=tftp 30008000 rootfs.jffs2;nand erase 1e00000 1400000;nand write.jffs2 30008000 1e00000 1400000
bootargs_jffs2=noinitrd root=/dev/mtdblock4 rootfstype=jffs2 init=/linuxrc console=ttyS0,115200
bootargs_cramfs=noinitrd root=/dev/mtdblock3 rootfstype=cramfs init=/linuxrc console=ttyS0,115200
bootargs_ubifs=console=ttyS0,115200 mem=64M ubi.mtd=6 root=ubi0:rootfs rootwait rootfstype=ubifs rw
bubifs=tftp 30008000 ubifs-$cpu.img;nand erase 6e00000 900000;nand write 30008000 6e00000 900000
cpu=arm920t
brdfs=tftp 30008000 ramdisk.gz;nand erase 500000 a00000;nand write 30008000 500000 500000
bootcmd_ramdisk=nand read 30008000 100000 400000;nand read 30800000 500000 500000;bootm 30008000
bootargs_ramdisk=console=ttyS0,115200 mem=64M initrd=0x30800000,16M root=/dev/ram0 rw loglevel=7
ip=192.168.1.111:192.168.1.3:192.168.1.1:255.255.255.0:localhost.com:eth0:off
bootargs_nfs=noinitrd console=ttyS0,115200 init=/linuxrc mem=64M loglevel=7 root=/dev/nfs rw nfsroot=192.168.1.3:/opt/rootfs ip=192.168.1.111:192.168.1.3:192.168.1.1:255.255.255.0:localhost.com:eth0:off
bootargs=noinitrd root=/dev/mtdblock3 rootfstype=cramfs init=/linuxrc console=ttyS0,115200
filesize=4DF000
fileaddr=30800000
netmask=255.255.255.0
ipaddr=192.168.1.111
serverip=192.168.1.3
bootcmd=run bootcmd_rootfs
stdin=serial
stdout=serial
stderr=serial
Environment size: 2064/131068 bytes
[ s3c2440@guowenxue ]#
[ s3c2440@guowenxue ]# set bkr 'tftp 30008000 linuxrom-s3c2440.bin;nand erase 100000 800000;nand write 30008000 100000 800000'
[ s3c2440@guowenxue ]# set bootargs 'console=ttyS0,115200 mem=64M init=/linuxrc rw loglevel=7'
[ s3c2440@guowenxue ]# set bootcmd_initramdisk 'nand read 30008000 100000 800000;bootm 30008000'
[ s3c2440@guowenxue ]# set bootcmd 'run bootcmd_initramdisk'
[ s3c2440@guowenxue ]# save
Saving Environment to NAND...
Erasing Nand...
Erasing at 0x60000 -- 100% complete.
Writing to Nand... Done
[ s3c2440@guowenxue ]# run bkr
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:00:3e:26:0a:6b
could not establish link
operating at 100M full duplex mode
Using dm9000 device
TFTP from server 192.168.1.3; our IP address is 192.168.1.111
Filename 'linuxrom-s3c2440.bin'.
Load address: 0x30008000
Loading: T T #################################################################
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done
Bytes transferred = 7187832 (6dad78 hex)
NAND erase: device 0 offset 0x100000, size 0x800000
Erasing at 0x8e0000 -- 100% complete.
OK
NAND write: device 0 offset 0x100000, size 0x800000
8388608 bytes written: OK
