嵌入式Linux Ramdisk文件系统制作(u-boot, busybox)

本文以mpc8247主板上移植Linux为例，详细讲解了嵌入式Linux Ramdisk文件系统制作过程，

图文并茂，并有排错方法，涉及u-boot和busybox

一、busybox的编译

    首先是交叉编译设置，打开busybox根目录下的Makefile，进行修改


一般情况下，为了让busybox能够独立于其他的库文件而可以单独运行，需要将busybox编译成静态的。

CODE:

#make menuconfig
Busybox Settings --->
    Build Options --->
        Build BusyBox as a static binary (no shared libs)        //静态
    Installation Options --->
        Don't use /usr        //make install的时候不会安装到根目录，而是安装到./_install
Linux System Utilities --->
    mdev        //相当于udev
    Support /etc/mdev.conf
    Support command execution at device addition/removal
Shells --->   
    Choose your default shell (msh)        //具有ash没有的功能，比如支持tab补齐，历史纪录等等的高级功能

而编译成静态的分为glibc和uclibc，如果系统没有安装uclibc的话，那就会报下面的错



解决办法是打开 applets/applets.c 将其中的错误注释掉



其他的busybox选项根据需要进行选择！

CODE:

#make
#make install

这样就在./_install目录下生成了busybox


二、ramdisk文件系统生成

上图中首先创见了一个10M的文件系统映象

然后使用losetup命令将此镜像与块设备/dev/loop0进行挂接

如果出现"ioctl: LOOP_SET_FD:设备或资源忙"，说明/dev/loop0设备还和一文件联系，可用losetup /dev/loop0查看地，并可用-d 删除


上图是用命令mke2fs来格式化此块设备/dev/loop0，其实就是格式化我们刚生成的那个文件系统镜像，ext2格式

上图是挂载文件系统镜像，可见经过刚才格式化之后的文件系统镜像里面只有lost+found这个文件夹

之后可以将步骤一中生成的_install目录下的所有文件拷贝进来即可，

/et/init.d/rcS文件如下修改



其他的系统配置文件可以根据需要进行更改

三、u-boot加载内核和文件系统

CODE:

=> tftp 800000 uImage; tftp a00000 rootfs.img; bootm 800000 a00000
Using FCC1 ETHERNET device
TFTP from server 192.168.0.102; our IP address is 192.168.0.20
Filename 'uImage'.
Load address: 0x800000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ###########################################
done
Bytes transferred = 1880231 (1cb0a7 hex)
Using FCC1 ETHERNET device
TFTP from server 192.168.0.102; our IP address is 192.168.0.20
Filename 'rootfs.img'.
Load address: 0xa00000
Loading: #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         ###################################
done
Bytes transferred = 3170368 (306040 hex)
## Booting image at 00800000 ...
   Image Name:   Linux-2.6.11
   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
   Data Size:    1880167 Bytes =  1.8 MB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
## cmdline at 0x007FFF00 ... 0x007FFF14
memstart    = 0x00000000
memsize     = 0x08000000
flashstart  = 0xFE000000
flashsize   = 0x01000000
flashoffset = 0x00033000
sramstart   = 0x00000000
sramsize    = 0x00000000
immr_base   = 0xF0000000
bootflags   = 0x00000001
vco         =    400 MHz
sccfreq     =    100 MHz
brgfreq     =    100 MHz
intfreq     =    400 MHz
cpmfreq     =    200 MHz
busfreq     =    100 MHz
ethaddr     = 00:08:02:06:10:00
IP addr     = 192.168.0.20
baudrate    = 115200 bps
## Loading RAMDisk Image at 00a00000 ...
   Image Name:   
   Image Type:   PowerPC Linux RAMDisk Image (uncompressed)
   Data Size:    3170304 Bytes =  3 MB
   Load Address: 00000000
   Entry Point:  00000000
   Verifying Checksum ... OK
   Loading Ramdisk to 07880000, end 07b86000 ... OK
Linux version 2.6.11 (root@Embedded001) (gcc version 3.4.3) #1 Fri Sep 26 11:08:35 CST 2008
Motorola PQ2 ADS PowerPC port
arch/ppc/syslib/m82xx_pci.c: The PCI bus is 33333333 Mhz.
Waiting 1 second after deasserting RST...
Built 1 zonelists
Kernel command line: console=ttyS0,115200
PID hash table entries: 1024 (order: 10, 16384 bytes)
Warning: real time clock seems stuck!
Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
Memory: 122272k available (2660k kernel code, 1524k data, 116k init, 0k highmem)
Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
checking if image is initramfs...it isn't (bad gzip magic numbers); looks like an initrd
Freeing initrd memory: 3096k freed
NET: Registered protocol family 16
PCI: Probing PCI hardware
dev = 0, pin = 1
slot = 0, dev = 0, pin = 1
dev = a0, pin = 1
slot = 20, dev = a0, pin = 1
dev = b8, pin = 1
slot = 23, dev = b8, pin = 1
dev = b9, pin = 1
slot = 23, dev = b9, pin = 1
PCI: Cannot allocate resource region 0 of device 0000:00:00.0
PCI: Cannot allocate resource region 1 of device 0000:00:00.0
SCSI subsystem initialized
Sangoma WANPIPE Router v1.1 (c) 1995-2000 Sangoma Technologies Inc.
devfs: 2004-01-31 Richard Gooch ([email][e-mail][/email])
devfs: boot_options: 0x1
Initializing Cryptographic API
Serial: CPM driver $Revision: 0.01 $
ttyS0 at MMIO 0xf0011a80 (irq = 4) is a CPM UART
ttyS1 at MMIO 0xf0011a00 (irq = 40) is a CPM UART
ttyS2 at MMIO 0xf0011a60 (irq = 43) is a CPM UART
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered
RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize
loop: loaded (max 8 devices)
nbd: registered device at major 43
Intel(R) PRO/1000 Network Driver - version 5.6.10.1-k2
Copyright (c) 1999-2004 Intel Corporation.
e100: Intel(R) PRO/100 Network Driver, 3.3.6-k2-NAPI
e100: Copyright(c) 1999-2004 Intel Corporation
ipddp.c:v0.01 8/28/97 Bradford W. Johnson <[email][e-mail][/email]>
ipddp0: Appletalk-IP Encap. mode by Bradford W. Johnson <[email][e-mail][/email]>
i2c /dev entries driver
eth0: FCC ENET Version 0.3, 00:08:02:86:10:00
eth1: FCC ENET Version 0.3, 00:08:02:46:10:00
NET: Registered protocol family 26
NET: Registered protocol family 2
IP: routing cache hash table of 1024 buckets, 8Kbytes
TCP established hash table entries: 8192 (order: 4, 65536 bytes)
TCP bind hash table entries: 8192 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 8192 bind 8192)
IPv4 over IPv4 tunneling driver
GRE over IPv4 tunneling driver
ip_conntrack version 2.1 (1024 buckets, 8192 max) - 248 bytes per conntrack
ip_tables: (C) 2000-2002 Netfilter core team
ipt_recent v0.3.1: Stephen Frost <[email][e-mail][/email]>.  [url][/url]
ClusterIP Version 0.6 loaded successfully
arp_tables: (C) 2002 David S. Miller
IPVS: Registered protocols (TCP, UDP, AH, ESP)
IPVS: Connection hash table configured (size=4096, memory=32Kbytes)
IPVS: ipvs loaded.
IPVS: [rr] scheduler registered.
IPVS: [wrr] scheduler registered.
IPVS: [lc] scheduler registered.
IPVS: [wlc] scheduler registered.
IPVS: [lblc] scheduler registered.
IPVS: [lblcr] scheduler registered.
IPVS: [dh] scheduler registered.
IPVS: [sh] scheduler registered.
IPVS: [sed] scheduler registered.
IPVS: [nq] scheduler registered.
Initializing IPsec netlink socket
NET: Registered protocol family 1
NET: Registered protocol family 17
NET: Registered protocol family 15
Bridge firewalling registered
Ebtables v2.0 registered
NET: Registered protocol family 4
NET: Registered protocol family 5
NET: Registered protocol family 9
X.25 for Linux. Version 0.2 for Linux 2.1.15
NET: Registered protocol family 8
NET: Registered protocol family 20
lec.c: Sep 26 2008 11:07:03 initialized
mpoa: /proc/mpoa initialized
mpc.c: Sep 26 2008 11:07:01 initialized
NET4: DECnet for Linux: V.2.5.68s (C) 1995-2003 Linux DECnet Project Team
DECnet: Routing cache hash table of 1024 buckets, 8Kbytes
NET: Registered protocol family 12
NET: Registered protocol family 19
802.1Q VLAN Support v1.8 Ben Greear <[email][e-mail][/email]>
All bugs added by David S. Miller <[email][e-mail][/email]>
SCTP: Hash tables configured (established 4096 bind 8192)
RAMDISK: ext2 filesystem found at block 0
RAMDISK: Loading 3096KiB [1 disk] into ram disk... done.
VFS: Mounted root (ext2 filesystem) readonly.
Mounted devfs on /dev
init started: BusyBox v1.7.2 (2008-09-26 10:46:55 CST)
starting pid 810, tty '': '/etc/init.d/rcS'
mdev: /sys/block: No such file or directory
mdev: /sys/class: No such file or directory
starting pid 813, tty '': '/bin/sh'
Processing /etc/profile... Done