Porting of Linux file systems-making JFFS2 file systems

The full name of the JFFS2 is the journalling Flash file system Version2, which was developed by Redhat Corporation (flash memory; English: Flash memory), and ^{its predecessor was jffs, The earliest support is nor Flash, since the 2.6 version of the support NAND flash, very suitable for use in embedded systems.}

The JFFS2 functions are as follows:

• Support NAND flash device.
• Hard links. This is a feature that jffs is unable to support in the file format.
• Compression. There are three kinds of algorithms: Zlib, Rubin and Rtime.
• Better performance.

Disadvantages:

• JFFS2 on Mount (Mount) will scan all the data, and then the file system directory stored in system memory, will be linear multiple growth, consuming a lot of time.
• JFFS2 does not have a write-back mechanism to temporarily store data in cache so that flash I/O is frequently active.
• JFFS2 design mechanism is too complex, code is difficult to read.

First, the transplant environment:

1. Ubuntu 10.10 Release

2, U-boot.bin

3. Target machine: fs_s5pc100 platform

4. Cross compiler ARM-CORTEX_A8-LINUX-GNUEABI-GCC

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second, the production JFFS2 File System

1. Configuration kernel supports JFFS2 file system

$ make Menuconfig

File system---> [*] Miscellaneous filesystems---> <*> journalling Flash File System v2 (JFFS2 ) Support

2, the compilation of zlib

       unzip zlib-1.2.3.tar.bz2 and go to zlib-1.2.3 configuration compilation installation

$ tar xvf zlib-1.2. 3 . tar.bz2 $ cd zlib-1.2. 3  $ . /Configure $ make $ make install

3. MTD Tool Compilation

Unzip the mtd-snapshot-20050519.tar.bz2 and enter Mtd/util to compile the installation

$ tar xvf  mtd-snapshot-20050519. tar.bz2 $ cd MTD/util $ make $ make install

So we have the MKFS.JFFS2 tool in our system.

4, JFFS2 file system image production

0x4000 --pad=0x800000  -/tftpboot

5, JFFS2 file system burn Write

30008000   ROOTFS.JFFS2 # NAND erase   500000  800000   # NAND write  30008000  Span style= "margin:0px; padding:0px; line-height:1.5; Color: #800080; " >500000  800000  

6. Set U-boot startup Parameters

# setenv Bootcmd  tftp  3300000033000000  # setenv Bootargs root=/dev/mtdblock2 init= /LINUXRC rootfstype=jffs2 rw console=ttysac0,115200  # savenv

Restart the development Board to see if it is successful.

Porting of Linux file systems-making JFFS2 file systems