plat->tacls:0

plat->twrph0:3

plat->twrph1:0

tacls:1

twrph0:1

twrph1:1

clkrate:100000000/*注意是8個0,實際就是是HCLK=100MHz*/

#define NS_IN_KHZ 10000000/*注意是7個0*/

static int s3c2410_nand_calc_rate(int wanted, unsigned long clk, int max)

{

int result;

result = (wanted * NS_IN_KHZ) / clk;

result++;

pr_debug("result %d from %ld, %dn", result, clk, wanted);

if (result > max) {

printk("%d ns is too big for current clock rate %ldn",

wanted, clk);

return -1;

}

if (result < 1)

result = 1;

return result;

}

s3c2410_nand_calc_rate(plat->twrph0, clkrate, 8)

即s3c2410_nand_calc_rate(3, 100000000, 8)

則wanted=3, clk=100000000,max=8

result = (wanted * NS_IN_KHZ) / clk

result =(3 * 10000000)/100000000顯然結(jié)果為0,result++;后返回值為1

按照這個函數(shù)的本意應(yīng)該是要返回4的,如果要修改的話,將它的值NS_IN_KHZ改為與HCLK相同的值,就可以了,我本來想改為100000000,想想如果uboot的FCLK改成202.8MHz,那么HCLK值為101.4MHz,則clkrate為101400000

result = (wanted * NS_IN_KHZ) / clk=(3 * 100000000)/101400000=0

還是不行啊,真該死,終于找到原因了,原來linux源碼是沒有問題的,在

linux-2.6.14linux-2.6.14archarmmach-s3c2410devs.c中

struct s3c2410_platform_nandsuperlpplatform={

tacls:0,

twrph0:30,/*原來寫的是3*/

twrph1:0,

sets:&nandset,

nr_sets:1,

};

串口打印出來內(nèi)容如下:

plat->tacls:0

plat->twrph0:30

plat->twrph1:0

tacls:1

twrph0:3

twrph1:1

clkrate:101400000

s3c2410-nand: timing: Tacls 10ns, Twrph0 30ns, Twrph1 10ns

5.Reading data from NAND FLASH without ECC is not recommended

VFS: Mounted root (cramfs filesystem) readonly.

Freeing init memory: 92K

Warning: unable to open an initial console.

Reading data from NAND FLASH without ECC is not recommended

sd_mod: version magic 2.6.8.1-ptx1 ARMv4 gcc-3.3 should be 2.6.14 ARMv4 gcc-3.4

usb_storage: version magic 2.6.8.1-ptx1 ARMv4 gcc-3.3 should be 2.6.14 ARMv4 gcc-3.4

usbvideo: version magic 2.6.8.1-ptx1 ARMv4 gcc-3.3 should be 2.6.14 ARMv4 gcc-3.4

ov511: version magic 2.6.8.1-ptx1 ARMv4 gcc-3.3 should be 2.6.14 ARMv4 gcc-3.4

說明一下:之前并沒有碰到這個問題,寫總結(jié)時故意去掉對devfs的支持,出現(xiàn)這樣的錯誤

Warning: unable to open an initial console.

原因是文件系統(tǒng)的dev目錄下沒有console節(jié)點,解決辦法有2個,

(1)制作文件系統(tǒng)時在dev目錄下建立console節(jié)點

(2)make menuconfig時加上對devfs的支持,就可以正常啟動

加上對devfs的支持,系統(tǒng)會根據(jù)需要自動創(chuàng)建所需節(jié)點

用ramdisk作根文件系統(tǒng):

(1)make menuconfig時要選擇支持ext2文件系統(tǒng)，因為ramdisk大多用ext2;

(2)make menuconfig時要選擇RAM disk support

(3)make menuconfig時還要選擇初始化ramdisk(initrd)

DeviceDrivers ->

Block Device->

<*>RAM disk support

[*]Initial RAM disk(initrd)support

(4)make menuconfig時還要設(shè)置好RAM disk的大小

DeviceDrivers ->

Block Device->

<*>RAM disk support

(16)Default number of RAM disks

(4096)Default RAM disk size(kbytes)

加載ramdisk時出現(xiàn)如下問題：

RAMDISK driver initialized:16RAM disks of4096Ksize 1024 blocksize

RAMDISK: Compressed image found at block 0

RAMDISK: incomplete write (-28 != 32768) 4194304

fs_names=ext2

root_mount_data=

VFS: Mounted root (ext2 filesystem).

Mounted devfs on /dev

Freeing init memory: 92K

attempt to access beyond end of device

ram0: rw=0, want=16518, limit=8192

EXT2-fs error (device ram0): ext2_get_inode: unable to read inode block - inode=1944, block=8258

Failed to execute /linuxrc.Attempting defaults...

attempt to access beyond end of device

ram0: rw=0, want=16514, limit=8192

EXT2-fs error (device ram0): ext2_get_inode: unable to read inode block - inode=1922, block=8256

Kernel panic - not syncing: No init found.Try passing init= option to kernel.

解決辦法：修改內(nèi)核關(guān)于Ramdisk的設(shè)置

make menuconfig

DeviceDrivers ->

Block Device->

<*>RAM disk support

(16)Default number of RAM disks16改為8

(4096)Default RAM disk size(kbytes)4096改為8192

板子的SDRAM是64M,16*4096kB = 8*8192kB = 64M

問題依然：

RAMDISK driver initialized:8RAM disks of8192K size 1024 blocksize

Mounted devfs on /dev

Freeing init memory: 92K

attempt to access beyond end of device

ram0: rw=0, want=16518, limit=16384

EXT2-fs error (device ram0): ext2_get_inode: unable to read inode block - inode=1944, block=8258

Failed to execute /linuxrc.Attempting defaults...

attempt to access beyond end of device

ram0: rw=0, want=16514, limit=16384

EXT2-fs error (device ram0): ext2_get_inode: unable to read inode block - inode=1922, block=8256

Kernel panic - not syncing: No init found.Try passing init= option to kernel.

修改

Default number of RAM disks值改為4

Default RAM disk size(kbytes)值改為16384

問題解決

為什么是16384呢?16384kb=16M,我制作的ramdisk鏡像大小為15M,這里的15M是未用gzip壓縮前的大小.

另外關(guān)于commandline的值:initrd=0x30800040,0x400000 root=/dev/ram init=/linuxrc console=ttySAC0

initrd=0x30800040是ramdisk在SDRAM中的地址,我用mkimage將ramdisk加了64(0x40)字節(jié)頭信息,制作成uboot可以識別的uRamdisk,然后下載到0x30800000,所以ramdisk的正真地址為0x30800040

0x400000(4M)為ramdisk的大小,要大于壓縮后的大小,我制作好的ramdisk大小為15M，壓縮后1.2M

root=/dev/ram也可以是root=/dev/ram0

我在nand flash的第四個分區(qū)下載了cramfs文件系統(tǒng),可以通過mount命令掛載該分區(qū)到tmp目錄下

# cd dev

# ls

consolekmemmmcptmxrdttyvcc

fbkmsgmtdblockptsrooturandomzero

fullmemnullptyshmusb

inputmiscportrandomttsvc

#mount /dev/mtdblock/3/tmp

另一種方法可以在系統(tǒng)啟動時就掛載該分區(qū)

修改/etc/init.d/rcS文件

內(nèi)容如下(藍(lán)色字體為添加的內(nèi)容):

#!/bin/sh

echo "mount cramfs from mtdblock/3"

/bin/mount /dev/mtdblock/3/tmp

echo "mount all"

/bin/mount –a

說明:/etc/init.d/rcS是可執(zhí)行的二進(jìn)制文件,系統(tǒng)啟動時被執(zhí)行