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lyq 2011-10-16记录?? mail: lianyq1986@163.com
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u-boot源码中的相应开发板配置头文件中增加以下内容
//jffs2 partitions support
#define CONFIG_CMD_JFFS2?? //增加JFFS2相关命令
#if 0 //单分区
/* No command line,one static partition */
#undef? CONFIG_CMD_MTDPARTS
#define CONFIG_JFFS2_DEV?? "nor1"
#define CONFIG_JFFS2_PART_SIZE? 0x400000 //分区大小
#define CONFIG_JFFS2_PART_OFFSET 0x0 //相对于flash物理地址的偏移
#else //多分区 可传递给kernel
#define CONFIG_CMD_MTDPARTS?? //增加mtd相关命令
#define CONFIG_FLASH_CFI_MTD? /*这个很重要,初始化添加设备名信息*/
#define CONFIG_MTD_DEVICE?? /* needed for mtdparts commands */
#define MTDIDS_DEFAULT??? "nor1=flash1,nor2=flash2"
#define MTDPARTS_DEFAULT?? "mtdparts=flash1:50m@0(system-1),-(config-1);"
????????? "flash2:50m@0(system-2),-(config-2)"
#endif
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//增加相应的环境变量值
#define CONFIG_EXTRA_ENV_SETTINGS???????????
?? "netdev=eth2 "?????????????????????????????????????????????????????
?? "ethact=FCC2 ETHERNET "?????
?? "consoledev=ttyS0 "????????????????????????????????????????????????
?? "ramdiskaddr=d00000 "??????????????????????????????????????????????
?? "ramdiskfile=ramdisk.img "????
?? "updatefile="MK_STR(CONFIG_UPDATEFILE)" "
?? "mtdids=" MTDIDS_DEFAULT " "????
?? "mtdparts=" MTDPARTS_DEFAULT " "???
?? "partition=nor1,0 "
?? "mtddevnum=0 "
?? "mtddevname=system-1 "
?? "fdtaddr="MK_STR(CONFIG_FDTADDR)" "????????????
?? "fdtfile=" MK_STR(CONFIG_FDTFILE) " "
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安装mkfs.jffs2命令工具方法
方法一、http://www.linux-mtd.infradead.org/
1.获取mtd-utils-1.1.0.tar.bz2压缩包
2.解压后，make (若编译不通过则进行根据错误提示判断是否执行第三步)
3.yum install lzo-devel
4.再make
5.将mkfs.jffs、mkfs.jffs2复制到/usr/sbin/目录下即可
方法二、在宿主机上(fedora系统)运行 yum install mtd-utils
命令使用实例：
mkfs.jffs2? -b -n -s 0x1000 -e 0x20000 -p 0x03200000 -d? rootfs/ -o? jffs2.img
说明：
根据目标板cpu支持的模式选择 -l(小端) -b(大端)??? ----这个很重要，不然u-boot识别不出来
页大小0x1000?? 4k
块大小0x20000? 128k
jffs2分区总空间0x03200000即50M,生成的jffs2.img并没有一下子分配50M
? -p,--pad[=SIZE]??????? Pad output to SIZE bytes with 0xFF. If SIZE is
????????????????????????? not specified,the output is padded to the end of
????????????????????????? the final erase block
? -r,-d,--root=DIR????? Build file system from directory DIR (default: cwd)
? -s,--pagesize=SIZE???? Use page size (max data node size) SIZE (default: 4KiB)
? -e,--eraseblock=SIZE?? Use erase block size SIZE (default: 64KiB)
? -c,--cleanmarker=SIZE? Size of cleanmarker (default 12)
? -m,--compr-mode=MODE?? Select compression mode (default: priortiry)
? -x,--disable-compressor=COMPRESSOR_NAME
????????????????????????? Disable a compressor
? -X,--enable-compressor=COMPRESSOR_NAME
????????????????????????? Enable a compressor
? -y,--compressor-priority=PRIORITY:COMPRESSOR_NAME
????????????????????????? Set the priority of a compressor
? -L,--list-compressors? Show the list of the avaiable compressors
? -t,--test-compression? Call decompress and compare with the original (for test)
? -n,--no-cleanmarkers?? Don't add a cleanmarker to every eraseblock
? -o,--output=FILE?????? Output to FILE (default: stdout)
? -l,--little-endian???? Create a little-endian filesystem
? -b,--big-endian??????? Create a big-endian filesystem
? -D,--devtable=FILE???? Use the named FILE as a device table file
? -f,--faketime????????? Change all file times to '0' for regression testing
? -q,--squash??????????? Squash permissions and owners making all files be owned by root
? -U,--squash-uids?????? Squash owners making all files be owned by root
? -P,--squash-perms????? Squash permissions on all files
????? --with-xattr??????? stuff all xattr entries into image
????? --with-selinux????? stuff only SELinux Labels into jffs2 image
????? --with-posix-acl??? stuff only POSIX ACL entries into jffs2 image
? -h,--help????????????? Display this help text
? -v,--verbose?????????? Verbose operation
? -V,--version?????????? Display version information
? -i,--incremental=FILE? Parse FILE and generate appendage output for it
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其他jffs2相关信息:
在linux的PC上挂载jffs2根文件系统映像
因为jffs2是构建于MTD设备上的文件系统，所以无法通过loop设备来挂载，但是可以通过mtdram设备来挂载。mtdram是在用RAM实现的MTD设备，可以通过mtdblock设备来访问。使用mtdram设备很简单，只要加载mtdram和mtdblock两个内核模块即可。这两个内核模块一般的linux内核发行版都有编译好的，直接用modprobe命令加载。
下面是具体步骤：
(1).加载mtdblock内核模块
modprobe mtdblock
(2).加载mtdram内核模块，将该设备的大小指定为jffs2根文件系统映像的大小，块擦除大小（即flash的块大小）指定为制作该jffs2根文件系统时“-e”参数指定的大小，缺省为64KB。下面两个参数的单位都是KB。
modprobe mtdram total_size=5120 erase_size=256
(3).这时将出现MTD设备/dev/mtdblock0，使用dd命令将jffs2根文件系统拷贝到/dev/mtdblock0设备中。
dd if=jffs2.img of=/dev/mtdblock0
(4).将保存了jffs2根文件系统的MTD设备挂载到指定的目录上。
mount -t jffs2 /dev/mtdblock0 /mnt/mtd
这之后就可以到/mnt/mtd目录查看、修改挂载的jffs2根文件系统了，修改后的jffs2根文件系统可以通过dd命令拷贝为一个jffs2的映像文件
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u-boot启动信息片段
ZN=> ls
Scanning JFFS2 FS: . done.
?-rwx------???? 8094 Sun Oct 16 07:30:56 2011 mpc8541cds.dtb
?-rwx------ 31457344 Sun Oct 16 07:30:56 2011 ramdisk.img
?-rwx------? 1658805 Sun Oct 16 07:30:56 2011 uImage
ZN=> boot
### JFFS2 loading 'uImage' to 0x500000
### JFFS2 load complete: 1658805 bytes loaded to 0x500000
### JFFS2 loading 'mpc8541cds.dtb' to 0xb00000
### JFFS2 load complete: 8094 bytes loaded to 0xb00000
### JFFS2 loading 'ramdisk.img' to 0xd00000
### JFFS2 load complete: 31457344 bytes loaded to 0xd00000
## Booting kernel from Legacy Image at 00500000 ...
?? Image Name:?? Linux-2.6.28.10
?? Image Type:?? PowerPC Linux Kernel Image (gzip compressed)
?? Data Size:??? 1658741 Bytes =? 1.6 MB
?? Load Address: 00000000
?? Entry Point:? 00000000
?? Verifying Checksum ... OK
## Loading init Ramdisk from Legacy Image at 00d00000 ...
?? Image Name:?? PPC RAMDISK
?? Image Type:?? PowerPC Linux RAMDisk Image (gzip compressed)
?? Data Size:??? 31457280 Bytes = 30 MB
?? Load Address: 00000000
?? Entry Point:? 00000000
?? Verifying Checksum ... OK
## Flattened Device Tree blob at 00b00000
?? Booting using the fdt blob at 0xb00000
?? Uncompressing Kernel Image ... OK
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