dm368 ecc 移植ubifs到dm368成功(2)

root@dm368-evm:~# ubiattach/dev/ubi_ctrl -m 3

UBI: attaching mtd3 to ubi0

UBI: physical eraseblock size: 131072 bytes (128 KiB)

UBI: logical eraseblock size: 129024 bytes

UBI: smallest flash I/O unit: 2048

UBI: sub-page size:512

UBI: VID header offset: 512 (aligned 512)

UBI: data offset: 2048

分析下UBI写数据的过程，

UBI DBG (pid 1484): ubi_io_write:write 512 bytes to PEB 57:0

int ubi_io_write(struct ubi_device*ubi, const void *buf, int pnum, int offset,

int len)

addr= (loff_t)pnum * ubi->peb_size + offset;

err= ubi->mtd->write(ubi->mtd, addr, len, &written, buf);

在io_init函数中可以看到几个变量的赋值；

ubi->peb_size = ubi->mtd->erasesize;

ubi->peb_count = mtd_div_by_eb(ubi->mtd->size,ubi->mtd);

ubi->flash_size= ubi->mtd->size;

从debug log来看，这里一次写了512字节，从某个block的起始page开始，offset是0；

那么到了nand mtd底层驱动，行为就是；

nand_write->nand_do_write_ops:

subpage= column || (writelen & (mtd->writesize - 1));

这里，subpage就是writelen，512；

也可以得知一点，ubifs没有使用oob，这跟jffs2和yaffs2是不同的；

/*Partial page write ? */

if(unlikely(column || writelen

writesize - 1))) {

cached= 0;

bytes= min_t(int, bytes - column, (int) writelen);

chip->pagebuf= -1;

memset(chip->buffers->databuf,0xff, mtd->writesize);

memcpy(&chip->buffers->databuf[column],buf, bytes);

wbuf= chip->buffers->databuf;

}

ret= chip->write_page(mtd, chip, wbuf, page, cached,

(ops->mode == MTD_OOB_RAW));

下面是write_page函数的代码；

static int nand_write_page(structmtd_info *mtd, struct nand_chip *chip,

const uint8_t *buf, int page, int cached,int raw)

{

intstatus;

chip->cmdfunc(mtd,NAND_CMD_SEQIN, 0x00, page);

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