android linux基础知识总结
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
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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。
#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
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解决办法是打开 applets/applets.c 将其中的错误注释掉
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其他的busybox选项根据需要进行选择！
#make
#make install
这样就在./_install目录下生成了busybox
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二、ramdisk文件系统生成
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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
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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
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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
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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
=> 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 ...
#p#副标题#e#
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][email protected][/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
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