查看Flash分区情况：

root@DD-WRT:~# cat /proc/mtd

dev:    size   erasesize  name

mtd0:   "RedBoot"

mtd1: 007c0000  "linux"

mtd2:   "rootfs"

mtd3:   "ddwrt"

mtd4:   "nvram"

mtd5:   "board_config"

mtd6:   "fullflash"

mtd7:   "fullboot"

root@DD-WRT:~#

用dd备份分区（如果有fullash分区)

root@DD-WRT:~# dd if=/dev/mtd6 of=/tmp/741_fullflash.bin

+ records in

+ records out

root@DD-WRT:~#

刷成编程器固件命令(前提是有fullash分区)

root@DD-WRT:~# mtd -r write fullflash /tmp/741_fullflash.bin

+ records in

+ records out

root@DD-WRT:~#

编程openwrt固件时修改mach-tl-mr3x20.c(对应3420)增加一个fullash

}, {

  .name  = "fullflash",

  .offset  = ,

  .size  = 0x800000,

  .mask_flags = MTD_WRITEABLE,

}

  .size  = 0x800000, 这个是flash大小8M

去掉  .mask_flags = MTD_WRITEABLE,是分区可以写，否者只可读

MTD subsystem has the following interfaces.

MTD character devices - usually referred to as /dev/mtd0, /dev/mtd1, and so on. These character devices provide I/O access to the raw flash. They support a number of ioctl calls for erasing eraseblocks, marking them as bad or checking if an eraseblock is bad, getting information about MTD devices, etc.

The sysfs interface is relatively newer and it provides full information about each MTD device in the system. This interface is easily extensible and developers are encouraged to use the sysfs interface instead of older ioctl or /proc/mtd interfaces, when possible. The sysfs interface for the mtd subsystem is documentated in the kernel, and currently can be found at Documentation/ABI/testing/sysfs-class-mtd.

The /proc/mtd proc file system file provides general MTD information. This is a legacy interface and the sysfs interface provides more information.