第五部分 linux 2.6内核的移植
1 内核移植过程
1.1 下载linux内核
从http://www.kernel.org/pub/linux/kernel/v2.6/linux2.6.14.1.
tar.bz2
下载linux2.6.14.1
内核至home/arm/dev_home/kernel.
[root@localhost ~]#su arm
[arm@localhost ~]#cd $KERNEL
[arm@localhost kernel]#tar xzvf
linux2.6.14.1.
tar.gz
[arm@localhost kernel]# pwd
/home/arm/dev_home/kernel
[arm@localhost kernel]# cd linux2.6.14
进入内核解压后的目录，以后示例中，只要是相对路径全部是相对于
/home/arm/dev_home/kernel/linux2.6.14/
此目录
1.2 修改Makefile
修改内核目录树根下的的Makefile,指明交叉编译器
[arm@localhost linux2.6.14]#
vi Makefile
找到ARCH和CROSS_COMPILE，修改
ARCH ?= arm
CROSS_COMPILE ?= armlinux
然后设置你的PATH环境变量，使其可以找到你的交叉编译工具链
[arm@localhost linux2.6.14]#
echo $PATH
/usr/local/arm/3.4.4/bin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/ly/bin
如果/usr/local/arm/3.4.4/bin搜索路径, 加入下面语句在~/.bashrc中
[arm@localhost linux2.6.14]#
vi ~/.bashrc
export PATH=/usr/local/arm/3.4.4/bin:$PATH
再重新登陆.
[arm@localhost linux2.6.14]#
su arm
1.3 设置flash分区
此处一共要修改3个文件，分别是:
1.3.1指明分区信息
在arch/arm/machs3c2410/
devs.c文件中:
[arm@localhost linux2.6.14]$
vi arch/arm/machs3c2410/
devs.c
添加如下内容：
#include <linux/mtd/partitions.h>
#include <linux/mtd/nand.h>
#include <asm/arch/nand.h>
...
/* NAND Controller */
1.建立Nand Flash分区表
/* 一个Nand Flash总共64MB, 按如下大小进行分区 */
static struct mtd_partition partition_info[] ={
{ /* 1MB */
name: "bootloader",
size: 0x00100000,
offset: 0x0,
},{ /* 3MB */
name: "kernel",
size: 0x00300000,
offset: 0x00100000,
}, { /* 40MB */
name: "root",
size: 0x02800000,
offset: 0x00400000,
}, { /* 20MB */
name: "user",
size: 0x00f00000,
offset: 0x02d00000,
}
};
name: 代表分区名字
size: 代表flash分区大小(单位：字节)
offset: 代表flash分区的起始地址(相对于0x0的偏移)
目标板计划分4个区，分别存放bootloader, kernel, rootfs以及以便以后扩展使用的用户文件系统空间。
各分区在Nand flash中起始地址. 分区大小. 记录如下：
bootloader:
start: 0x00000000
len: 0x00100000
1MB
kernel:
start: 0x00100000
len: 0x00300000
3MB
rootfs:
start: 0x00400000
len: 0x02800000
40MB
User:
start: 0x02c00000
len: 0x01400000
20MB
2. 加入Nand Flash分区
struct s3c2410_nand_set nandset ={
nr_partitions: 4, /* the number of partitions */
partitions: partition_info, /* partition table */
};
nr_partitions: 指明partition_info中定义的分区数目
partitions: 分区信息表
3. 建立Nand Flash芯片支持
struct s3c2410_platform_nand superlpplatform={
tacls:0,
twrph0:30,
twrph1:0,
sets: &nandset,
nr_sets: 1,
};
tacls, twrph0, twrph1的意思见S3C2410手册的63,
这3个值最后会被设置到NFCONF中,见S3C2410手册66.
sets: 支持的分区集
nr_set:分区集的个数
4. 加入Nand Flash芯片支持到Nand Flash驱动
另外，还要修改此文件中的s3c_device_nand结构体变量,添加对dev成员的赋值
struct platform_device s3c_device_nand = {
.name = "s3c2410nand",
/* Device name */
.id = 1,
/* Device ID */
.num_resources = ARRAY_SIZE(s3c_nand_resource),
.resource = s3c_nand_resource, /* Nand Flash Controller Registers */
/* Add the Nand Flash device */
.dev = {
.platform_data = &superlpplatform
}
};
name: 设备名称
id: 有效设备编号,如果只有唯一的一个设备为1,
有多个设备从0开始计数.
num_resource: 有几个寄存器区
resource: 寄存器区数组首地址
dev: 支持的Nand Flash设备
1.3.2 指定启动时初始化
kernel启动时依据我们对分区的设置进行初始配置
修改arch/arm/machs3c2410/
machsmdk2410.
c文件
[arm@localhost linux2.6.14]$
vi arch/arm/machs3c2410/
machsmdk2410.
c
修改smdk2410_devices[].指明初始化时包括我们在前面所设置的flash分区信息
static struct platform_device *smdk2410_devices[] __initdata = {
&s3c_device_usb,
&s3c_device_lcd,
&s3c_device_wdt,
&s3c_device_i2c,
&s3c_device_iis,
/* 添加如下语句即可 */
&s3c_device_nand,
};
保存,退出。
1.3.3 禁止Flash ECC校验
我们的内核都是通过UBOOT写到Nand Flash的, UBOOT通过的软件ECC算法产生ECC校验码, 这与内核
校验的ECC码不一样, 内核中的ECC码是由S3C2410中Nand Flash控制器产生的. 所以, 我们在这里选择禁止
内核ECC校验.
修改drivers/mtd/nand/s3c2410.c 文件:
[arm@localhost linux2.6.14]$
vi drivers/mtd/nand/s3c2410.c
找到s3c2410_nand_init_chip()函数，在该函数体最后加上一条语句:
chip>
eccmode = NAND_ECC_NONE;
保存,退出。
OK.我们的关于flash分区的设置全部完工.
1.4 配置内核
1.4.1 支持启动时挂载devfs
为了我们的内核支持devfs以及在启动时并在/sbin/init运行之前能自动挂载/dev为devfs文件系统，修改
fs/Kconfig文件
[arm@localhost linux2.6.14]$
vi fs/Kconfig
找到menu "Pseudo filesystems"
添加如下语句：
config DEVFS_FS
bool "/dev file system support (OBSOLETE)"
default y
config DEVFS_MOUNT
bool "Automatically mount at boot"
default y
depends on DEVFS_FS
1.4.2配置内核产生.config文件
[arm@localhost linux2.6.14]$
cp arch/arm/configs/smdk2410_defconfig .config
[arm@localhost linux2.6.14]$
make menuconfig
在smdk2410_defconfig基础上，我所增删的内核配置项如下：
Loadable module support >
[*] Enable loadable module support
[*] Automatic kernel module loading
System Type >
[*] S3C2410 DMA support
Boot options >
Default kernel command string:
noinitrd root=/dev/mtdblock2 init=/linuxrc console=ttySAC0,115200
#说明：mtdblock2代表我的第3个flash分区，它是我的rootfs
# console=ttySAC0,115200使kernel启动期间的信息全部输出到串口0上.
# 2.6内核对于串口的命名改为ttySAC0，但这不影响用户空间的串口编程。
# 用户空间的串口编程针对的仍是/dev/ttyS0等
Floating point emulation >
[*] NWFPE math emulation
This is necessary to run most binaries!!!
#接下来要做的是对内核MTD子系统的设置
Device Drivers >
Memory Technology Devices (MTD) >
[*] MTD partitioning support
#支持MTD分区，这样我们在前面设置的分区才有意义
[*] Command line partition table parsing
#支持从命令行设置flash分区信息，灵活
RAM/ROM/Flash chip drivers >
<*> Detect flash chips by Common Flash
Interface (CFI) probe
<*> Detect nonCFI
AMD/JEDECcompatible
flash chips
<*> Support for Intel/Sharp flash chips
<*> Support for AMD/Fujitsu flash chips
<*> Support for ROM chips in bus mapping
NAND Flash Device Drivers >
<*> NAND Device Support
<*> NAND Flash support for S3C2410/S3C2440 SoC
Character devices >
[*] Nonstandard
serial port support
[*] S3C2410 RTC Driver
#接下来做的是针对文件系统的设置，本人实验时目标板上要上的文件系统是cramfs,故做如下配置
File systems >
<> Second extended fs support #去除对ext2的支持
Pseudo filesystems >
[*] /proc file system support
[*] Virtual memory file system support (former shm fs)
[*] /dev file system support (OBSOLETE)
[*] Automatically mount at boot (NEW)
#这里会看到我们前先修改fs/Kconfig的成果，devfs已经被支持上了
Miscellaneous filesystems >
<*> Compressed ROM file system support (cramfs)
#支持cramfs
Network File Systems >
<*> NFS file system support
保存退出，产生.config文件.
.config文件能从提供的2.4.14.1的内核包中找到,文件名为config.back.
1.4.3编译内核
[arm@localhost linux2.6.14]$
make zImage
注意：若编译内核出现如下情况
LD .tmp_vmlinux1
armlinuxld:
arch/arm/kernel/vmlinux.lds:1439: parse error
make: *** [.tmp_vmlinux1] Error 1
解决方法：修改arch/arm/kernel/vmlinux.lds
[arm@localhost linux2.6.14]$
vi arch/arm/kernel/vmlinux.lds
将文件尾2条的ASSERT注释掉（1439行）
/* ASSERT((__proc_info_end __
proc_info_begin), "missing CPU support") */
/* ASSERT((__arch_info_end __
arch_info_begin), "no machine record defined") */
然后重新make zImage即可
1.4.4 下载zImage到开发板
CRANE2410 # tftp 0x30008000 zImage
TFTP from server 192.168.1.6; our IP address is 192.168.1.5
Filename 'zImage'.
Load address: 0x30008000
Loading: #################################################################
#################################################################
#################################################################
#############################
done
Bytes transferred = 1142856 (117048 hex)
CRANE2410 # bootm 0x30008000
1.4.5 目标板启动信息如下
IRQ Stack: 33fc149c
FIQ Stack: 33fc249c
1
1
DRAM Configuration:
Bank #0: 30000000 64 MB
1
NAND:64 MB
In: serial
Out: serial
Err: serial
Hit any key to stop autoboot: 0
zImage magic = 0x016f2818
NOW, Booting Linux......
Uncompressing Linux............................................................................ don.Linux version 2.6.14.1 (arm@dozec) (gcc
version 3.3.2) #15 Thu Jul 6 14:26:29 CST 2006
CPU: ARM920Tid(wb) [41129200] revision 0 (ARMv4T)
Machine: SMDK2410
Warning: bad configuration page, trying to continue
Memory policy: ECC disabled, Data cache writeback
CPU S3C2410A (id 0x32410002)
S3C2410: core 202.800 MHz, memory 101.400 MHz, peripheral 50.700 MHz
S3C2410 Clocks, (c) 2004 Simtec Electronics
CLOCK: Slow mode (1.500 MHz), fast, MPLL on, UPLL on
CPU0: D VIVT writeback
cache
CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
Built 1 zonelists
Kernel command line: noinitrd root=/dev/mtdblock2 init=/linuxrc console=ttySAC0,115200
irq: clearing subpending status 00000002
PID hash table entries: 128 (order: 7, 2048 bytes)
timer tcon=00500000, tcnt a509, tcfg 00000200,00000000, usec 00001e4c
Console: colour dummy device 80x30
Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
Inodecache
hash table entries: 2048 (order: 1, 8192 bytes)
Memory: 16MB = 16MB total
Memory: 13712KB available (1927K code, 422K data, 104K init)
Mountcache
hash table entries: 512
CPU: Testing write buffer coherency: ok
softlockup thread 0 started up.
NET: Registered protocol family 16
S3C2410: Initialising architecture
SCSI subsystem initialized
usbcore: registered new driver usbfs
usbcore: registered new driver hub
S3C2410 DMA Driver, (c) 20032004
Simtec Electronics
DMA channel 0 at c1800000, irq 33
DMA channel 1 at c1800040, irq 34
DMA channel 2 at c1800080, irq 35
DMA channel 3 at c18000c0, irq 36
NetWinder Floating Point Emulator V0.97 (double precision)
devfs: 20040131
Richard Gooch (rgooch@atnf.csiro.au)
devfs: boot_options: 0x1
Console: switching to colour frame buffer device 80x25
fb0: Virtual frame buffer device, using 1024K of video memory
S3C2410 RTC, (c) 2004 Simtec Electronics
s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2410
s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2410
s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2410
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
Cirrus Logic CS8900A driver for Linux (Modified for SMDK2410)
eth0: CS8900A rev E at 0xe0000300 irq=53, no eeprom , addr: 08: 0:3E:26:0A:5B
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c2410nand:
mapped registers at c1980000
s3c2410nand:
timing: Tacls 10ns, Twrph0 30ns, Twrph1 10ns
NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V 8bit)
NAND_ECC_NONE selected by board driver. This is not recommended !!
Scanning device for bad blocks
Creating 4 MTD partitions on "NAND 64MiB 3,3V 8bit":
0x000000000x00100000
: "bootloader"
0x001000000x00500000
: "kernel"
0x005000000x02d00000
: "root"
0x02d000000x03c00000
: "User"
usbmon: debugfs
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