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Linux version 2.6.26.5, ARM Linux Kernel on embedded device, NAND-based device. I'm at Busybox rescue shell (ash), with restricted command set. How to manually mount the virtual file systems, to copy the MTD flash partitions into /tmp? I need backup the flash partitions use nanddump.

# cat /proc/mtd dev: size erasesize name mtd0: 00004000 00004000 "NAND BootAgent" mtd1: 000fc000 00004000 "Linux Kernel" mtd2: 00d00000 00004000 "Root" mtd3: 00100000 00004000 "Config" mtd4: 00100000 00004000 "Debug" mtd5: 00000000 00004000 "Data" nanddump -f /tmp/mtd0.bin /dev/mtd0

What virtual file systems I should mount for this? Something like this

# mount -t proc proc /proc # mount -t sysfs sysfs /sys # mount -t tmpfs tmpfs /tmp # mount -t tmpfs none /dev # mknod -m 666 /dev/zero c 1 5 # mknod -m 666 /dev/null c 1 3 # mkdir /dev/pts # mount -t devpts none /dev/pts

or I need use commands like this

mount -t proc proc /proc mount -t sysfs sysfs /sys mount -t tmpfs -o size=20M,mode=0755 tmpfs /dev mdev -s cd /dev nanddump -f /tmp/mtd0.bin /dev/mtd0
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Typically, there will also be a /dev/mtdblockN device, one for each MTD partition. These are block devices you can use with nanddump, dd, mount, etc.

You need to create a mount point directory some place (mkdir -p /media/mnt) for example. Then it depends on what file system your NAND partition is using. For example, I have two UBIFS NAND partitions and would use commands like:

/usr/bin/ubiattach /dev/ubi_ctrl -m <MTD_partition> -O <block_size> /bin/mount -t ubifs ubi1:rootfs0 /media/mnt

If the partition has no file system (like a kernel image) then nanddump would work.

nanddump -f /tmp/mtd0.bin /dev/mtdblock0

If the partition is a data (NOR) flash then dd will work.

dd if=/dev/mtdblock1 of=/tmp/mtd1.bin
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  • So, I need to mount every partition in order to dump it? I mean like this, for example, for nvram file: # mknod -m 644 /dev/mtd9 c 90 9 # mknod -m 644 /dev/mtdblock9 b 31 9 # mount -t jffs2 /dev/mtdblock9 /mnt Commented Apr 19, 2019 at 22:37

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