Clarification on multiple mtdram devices - HowTo

MikeW mw_phil at
Wed Mar 21 08:39:54 EDT 2007

MikeW <mw_phil <at>> writes:

>From a (much) earlier post, I note that the mtdram driver can emulate
>several /dev/mtd's by "loading the driver more than once".
>Does this mean modprobing *once* but then setting up multiple
>device nodes with the same major number and different minor numbers ?
>I presume this also implies that each device must have the same
size & erasesize.
> Regards,
> MikeW

Found out about doing this here:

(I would like a section doing this properly on the MTD website FAQ
written by an authoritative person - please !)
To start we load a few modules, creating a fake 32M flash device
 in RAM and ensure we have appropriate /dev/ entries:

# modprobe mtdcore
# modprobe mtdram total_size=32768 erase_size=256
# mkdir /dev/mtdblock ; for i in 0 1 2 3 ;
 do mknod /dev/mtdblock/$i b 31 $i; done

Then we write the contents of one of the JFFS2 images
to the MTD RAM device, and take a look:

# dd if=gpe-image-h3600-20050407124742.rootfs.jffs2 of=/dev/mtdblock/0
# mkdir -p /mnt/ipaq/
# mount -t jffs2 /dev/mtdblock/0 /mnt/ipaq
# cd /mnt/ipaq; ls;

The output will be something like:

	bin  boot  dev  etc  home  lib  media  mnt  proc  sbin
  sys  tmp  usr  var

More information about the linux-mtd mailing list