作者：孫曉明，華清遠見嵌入式學院講師。

uboot源碼默認是不支持yaffs文件系統(tǒng)的，所以我們需要自己修改源碼進行支持。

首先我們進入U-Boot源碼目錄添加對yaffs鏡像燒寫的支持.

在common/cmd_nand.c里仿照jffs2來寫一些yaffs的內容：

在：

U_BOOT_CMD(nand, 5, 1, do_nand,

"nand - NAND sub-systemn",

"info - show available NAND devicesn"

"nand device [dev] - show or set current devicen"

"nand read[.jffs2] - addr off|partition sizen"

"nand write[.jffs2] - addr off|partition size - read/write `size' bytes startingn"

" at offset `off' to/from memory address `addr'n"

之后添加nand read.yaffs 的使用說明：

"nand read.yaffs - addr off|partition sizen"

"nand write.yaffs - addr off|partition size - read/write `size' bytes startingn"

然后在nand命令的處理函數(shù)里do_nand中增加對write.yaffs的支持，do_nand在common/cmd_nand.c中實現(xiàn)：

在：

if (s != NULL &&

(!strcmp(s, ".jffs2") || !strcmp(s, ".e") || !strcmp(s, ".i"))) {

…….

的判斷后面加：

else if (s != NULL &&

(!strcmp(s, ".yaffs") || !strcmp(s, ".e") || !strcmp(s, ".i"))) {

if (read) {

/* read */

nand_read_options_t opts;

memset(&opts, 0, sizeof(opts));

opts.buffer = (u_char*) addr;

opts.length = size;

opts.offset = off;

opts.readoob = 1;

opts.quiet = quiet;

ret = nand_read_opts(nand, &opts);

} else {

/* write */

nand_write_options_t opts;

memset(&opts, 0, sizeof(opts));

opts.buffer = (u_char*) addr;

opts.length = size;

opts.offset = off;

/* opts.forcejffs2 = 1; */

//opts.pad = 1;

opts.noecc = 1;

opts.writeoob = 1;

opts.blockalign = 1;

opts.quiet = quiet;

ret = nand_write_opts(nand, &opts);

}

}

由于前面設置了opts.noecc = 1,不使用ecc校驗碼，燒寫過程中會提示這個信息：

Writing data without ECC to NAND-FLASH is not recommended

Writing data without ECC to NAND-FLASH is not recommended

Writing data without ECC to NAND-FLASH is not recommended

Writing data without ECC to NAND-FLASH is not recommended

Writing data without ECC to NAND-FLASH is not recommended

可以修改driver/mtd/nand/nand_base.c文件的nand_write_page函數(shù)，將它去掉，修改如下：

case NAND_ECC_NONE:

//printk (KERN_WARNING "Writing data without ECC to NAND-FLASH is not ecommendedn");

this->write_buf(mtd, this->data_poi, mtd->oobblock);

break;

修改完這些，U－BOOT就可以支持yaffs文件鏡像的燒寫了。

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