UM0851 datasheet(135/245 Pages) STMICROELECTRONICS

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UM0851

Non-volatile memory device drivers

Doc ID 16604 Rev 2

135/245

5.1.5

NAND Flash file system image creation

YAFFS2 image creation

To create the YAFFS2 file system image for 512 byte page NAND Flash, use the command:

# mkyaffsimage <layout no> <dir name> <image name>

To create the YAFFS2 file system image for 2048 byte page NAND Flash, use the

command:

# mkyaffs2image <layout no> <dir name > <image name >

These commands create the image, which contains OOB. Hence for a 512 byte page NAND

Flash, the image size must be divisible by 528 (512 byte data + 16 byte OOB).

JFFS2 image creation

To create the JFFS2 file system image for a 512 byte page NAND Flash, use the command:

# mkfs.jffs2 -n -p -l -s 0x200 -e 0x4000 -r <dir name > -o <image name >

To create the JFFS2 file system image for a 2048 byte page NAND Flash, use the

command:

# mkfs.jffs2 -n -p -l -s 0x800 -e 0x20000 -r <dir name > -o <image name >

-n: don't add a cleanmarker to every eraseblock

-p: add pad bytes to the end of the final erase block

-l: create a little-endian file-system

-s: page size

-e: erase block size

These commands create the image, which does not contain OOB. Hence for 512 byte page

NAND Flash, the image size must be divisible by 512 (512 byte data).

5.1.6

NAND device driver performance

The performance measurement has been performed using:

●

Hardware: ARM926EJS (333 MHz), STMicroelectronics NAND 512W3A2CZA6 Flash.

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Test file system on the NAND Flash: YAFFS2 and JFFS2 (for /dev/mtdblock7)

●

Kernel: Linux-2.6.27.

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Driver: DMA was disabled

Results for YAFFS2

Mount YAFFS2 fs and write/read to a file. The sequence is as follows:

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