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研发客服linux内核最小系统，使用内核版本：
1，FL2440板子的基本硬件：晶振12MHZ
CPU |
型号为S3C2440，基于ARM920T,指令集ARMV4,时钟主频400MHz |
SDRAM |
H57V2562GTR-75C 2片*32MB=64MB,挂载于nGCS6 (0x3000 0000) |
NANDFLASH |
型号：K9F2G08U0B 大小：256MB |
Network Adapter |
DM9000AEP 10/100M自适应，挂载于nGCS4 (0x2000 0000) |
|
5个LED(LED0~3)I/O口指示灯,LED5电源指示灯，LED9核心板3.3V指示灯 LED0~LED3分别接GPB6，GPB6，GPB8，GPB10 |
|
BEEP（蜂鸣器） |
接在GPB0/TOUT0 |
2，首先说明make menuconfig，Kconfig，.config之间的关系：
1）make menuconfig首先读取顶层Kconfig文件，生成选择界面。
2）使能arch/$SRCARCH/Kconfig，最终生成.config（控制编译）
Kconfig文件：
#
# For a description of the syntax of this configuration file,
# see Documentation/kbuild/kconfig-language.txt.
#
mainmenu "Linux/$ARCH $KERNELVERSION Kernel Configuration"
config SRCARCH
string
option env="SRCARCH"
source "arch/$SRCARCH/Kconfig"
相当于使能arch/arm/Kconfig，并且递归进入各个目录Kconfig，生成选项界面。
3）当make编译，就会读出生成的.config文件，根据其中的选项编译相应模块。
若选择
3，linux-3.8内核配置
1）修改顶层Makefile
# CROSS_COMPILE specify the prefix used for all executables used
# during compilation. Only gcc and related bin-utils executables
# are prefixed with $(CROSS_COMPILE).
# CROSS_COMPILE can be set on the command line
# make CROSS_COMPILE=ia64-linux-
# Alternatively CROSS_COMPILE can be set in the environment.
# A third alternative is to store a setting in .config so that plain
# "make" in the configured kernel build directory always uses that.
# Default value for CROSS_COMPILE is not to prefix executables
# Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
export KBUILD_BUILDHOST := $(SUBARCH)
ARCH ?= arm
CROSS_COMPILE ?= /opt/buildroot-2011.11/arm920t/usr/bin/arm-linux-
# Architecture as present in compile.h
UTS_MACHINE := $(ARCH)
SRCARCH := $(ARCH)
# Additional ARCH settings for x86
ifeq ($(ARCH),i386)
2)修改分区arch/arm/mach-s3c24xx/common-smdk.c,以下供参考，也可按自己想法修改。修改分区要与根文件系统指定快设备对应。
static struct mtd_partition smdk_default_nand_part[] = {
[0] = {
.name = "mtdblock0_u-Boot 1MB ",
.size = SZ_1M,
.offset = 0,
},
[1] = {
.name = "mtdbolck1_kernel 15MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 15,
},
[2] = {
.name = "mtdbolck2_ramdisk 20MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 20,
},
[3] = {
.name = "mtdblock3_cramfs 20MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 20,
},
[4] = {
.name = "mtdblock4_jffs2 40MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 40,
},
[5] = {
.name = "mtdblock5_yaffs2 40MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 40,
},
[6] = {
.name = "mtdblock6_ubifs 40MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 40,
},
[7] = {
.name = "mtdblock7_apps 40MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 40,
},
[8] = {
.name = "mtdblock8_data 40MB",
.offset = MTDPART_OFS_NXTBLK,
.size = SZ_1M * 40,
},
};
4)修改板子时钟参数arch/arm/mach-s3c24xx/mach-smdk2440.c
s3c24xx_init_clocks(16934400)修改为s3c24xx_init_clocks(12000000);
5）修改机器代码和u-boot相对应。有u-boot使用的是MACH_TYPE_MINI2440，
机器代码号为1999。修改arch/arm/tools/mach-types如下：
s3c2440 ARCH_S3C2440 S3C2440 1999
mini2440 MACH_MINI2440 MINI2440 362
6）修改drivers/mtd/onenand/onenand_bbt.c如下：
static struct nand_bbt_descr largepage_memorybased = {
.options = 0,
.offs = 0,
.len = 1,
.pattern = scan_ff_pattern,
};
7) 修改串口：drivers/tty/serial/samsung.c
#define S3C24XX_SERIAL_NAME "ttyS"
8）make menuconfig选项配置。FL2440板子使用的s3c2440的cpu与s3c2410类似，
所以选择内核中arch/arm/configs目录下的s3c2410_defconfig为模板修改。
[zhouguangfeng@localhost linux-3.8]$ cp arch/arm/configs/s3c2410_defconfig .
[zhouguangfeng@localhost linux-3.8]$ mv s3c2410_defconfig .config
[zhouguangfeng@localhost linux-3.8]$ make menuconfig
在根文件系统已经制作好的前提下，将根文件系统编译入内核：
General setup --->
[*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
(../../rootfs/rootfs) Initramfs source file(s)
红色字体指明根文件系统的目录。make编译。。。（机器不给力的，这时候可以喝杯咖啡。。。）
当编译结束之后，在arch/arm/boot下有一个zImage文件，它是ARM Linux常用的一种压缩
映像文件，uImage是U-boot专用的映像文件，它是在zImage之前加上一个长度为0x40的“头”，
说明这个映像文件的类型、加载位置、生成时间、大小等信息。就是，直接从uImage的
0x40位置开始执行，zImage和uImage没有任何区别。由于最后是由u-boot引导启动，
需要使用u-boot编译后tools目录下mkimage工具，加上一个header。也可以将mkimage放到
/usr/bin下，这里就直接指定它的路径。
修改在Makefile
# This allow a user to issue only 'make' to build a kernel including modules
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
cp -f arch/arm/boot/zImage .
../../systools/mkimage -A arm -O linux -T kernel -C none -a 30008000 -e 30008040
-n "Linux Kernel" -d zImage linuxrom-s3c2440_zhou.bin
rm -f zImage
ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
KBUILD_CFLAGS += -Os
蓝色标记为mkimage路径，具体每个参数说明，参考http://blog.csdn.net/lusehu/article/details/6438512
完成之后将其拷贝到tftp目录下
[zhouguangfeng@localhost linux-3.8]$ du -h /tftp/linuxrom-s3c2440_zhou.bin
3.4M /tftp/linuxrom-s3c2440_zhou.bin
[zhouguangfeng@localhost linux-3.8]$ mv linuxrom-s3c2440_zhou.bin /tftp
4，添加u-boot参数支持（u-boot-2010.09）：
[ s3c2440@zhou]# set bkr 'tftp 30008000 linuxrom-s3c2440_zhou.bin;nanderase 100000 800000;nand write 30008000 100000 800000'
[ s3c2440@zhou]# set bootcmd_initramfs 'nand read 30008000 100000 800000;bootm 30008000'
[ s3c2440@zhou]# set bootargs 'console=ttyS0,115200 mem=64M init=/linuxrc rw loglevel=7'
[ s3c2440@zhou]# set bootcmd 'run bootcmd_initramfs'
[ s3c2440@zhou]# save
Saving Environment to NAND...
Erasing Nand...
Erasing at 0x60000 -- 100% complete.
Writing to Nand... Done
[ s3c2440@zhou ]# pri
cpu=s3c2440
bbl=tftp 30008000 u-boot-$cpu.bin;nand erase 0 100000;nand write 30008000 0 $filesize
norbbl=erase bank 1; tftp 30008000 u-boot-$cpu.bin;cp.b 30008000 0 $filesize
blx=tftp 30008000 linuxrom-$cpu.bin;nand erase 100000 F00000;nand write 30008000 100000 $filesize
bramdisk=tftp 30800000 ramdisk-$cpu.rootfs;nand erase 1000000 1400000;nand write 30800000 1000000 $filesize
bcramfs=tftp 30800000 cramfs-$cpu.rootfs;nand erase 2400000 1400000;nand write 30800000 2400000 $filesize
bubifs=tftp 30800000 ubifs-$cpu.rootfs;nand erase 8800000 2800000;nand write 30800000 8800000 $filesize
bootcmd_ramdisk=nand read 30008000 100000 F00000;nand read 30800000 1000000 1400000;bootm 30008000
tb=tftp 30008000 linuxrom-$cpu.bin;bootm 30008000
bootargs_ramdisk=console=ttyS0,115200 root=/dev/ram0 initrd=0x30800000,16M init=/linuxrc mem=64M rw loglevel=7
bootargs_cramfs=console=ttyS0,115200 root=/dev/mtdblock3 rootfstype=cramfs init=/linuxrc mem=64M noinitrd loglevel=7
bootargs_jffs2=console=ttyS0,115200 root=/dev/mtdblock4 rootfstype=jffs2 init=/linuxrc mem=64M rw noinitrd loglevel=7
bootargs_ubifs=console=ttyS0,115200 ubi.mtd=6 root=ubi0:rootfs rootwait rootfstype=ubifs init=/linuxrc mem=64M noinitrd rw loglevel=7
mtdparts=mtdparts=nand0:1m(uboot),15m(kernel),20m(ramdisk),20m(cramfs),20m(jffs2),20m(yaffs2),20m(ubifs),-(users)
baudrate=115200
ethaddr=08:08:11:18:12:27
ethact=dm9000
bootcmd_yaffs=nand read 30008000 100000 800000;bootm 30008000
bootcmd_yaffs2=nand read 30008000 100000 800000;bootm 30008000
bootdelay=1
bootcmd=run bootcmd_rootfs
bootcmd_rootfs=nand read 30008000 100000 800000;bootm 30008000
byaffs2=tftp 30008000 rootfs_yaffs2.bin;nand erase 6000000 2800000;nand write 30008000 6000000 400000
bkr=tftp 30008000 linuxrom-s3c2440_zhou.bin;nand erase 100000 f00000;nand write 30008000 100000 800000
filesize=350440
fileaddr=30008000
gatewayip=192.168.1.1
netmask=255.255.255.0
ipaddr=192.168.1.224
serverip=192.168.1.3
bootargs=console=ttyS0,115200 mem=64M rw loglevel=7 init=/linuxrc
bootargs_initramfs=console=ttyS0,115200 mem=64M rw loglevel=7 init=/linuxrc
stdin=serial
stdout=serial
stderr=serial
Environment size: 2144/131068 bytes
[ s3c2440@zhou ]# OK!
[ s3c2440@zhou ]# run bkr
dm9000 i/o: 0x20000300, id: 0x90000a46
DM9000: running in 16 bit mode
MAC: 08:08:11:18:12:27
operating at 100M full duplex mode
Using dm9000 device
TFTP from server 192.168.1.3; our IP address is 192.168.1.224
Filename 'linuxrom-s3c2440_zhou.bin'.
Load address: 0x30008000
Loading: #################################################################
#################################################################
#################################################################
##########################################
done
Bytes transferred = 3474496 (350440 hex)
NAND erase: device 0 offset 0x100000, size 0xf00000
Erasing at 0xfe0000 -- 100% complete.
OK
NAND write: device 0 offset 0x100000, size 0x800000
8388608 bytes written: OK
[ s3c2440@zhou ]# boot