running out of space dd'ing JFFS2 image to /dev/mtdblock/0

[Robert P. J. Day]

  just for curiosity's sake, after i build a JFFS2 image using
mkfs.jffs2, i want to mount out to verify its contents.  to do that, i
use a recipe i patched together a while back involving loading the
appropriate modules, creating /dev/mtdblock/0, dd'ing the image to
that device, then mounting it.

  however, this morning, in trying this with a larger-than-normal
JFFS2 image, i get:

  # dd bs=4096 if=soefsimage of=/dev/mtdblock/0
  # dd: writing `/dev/mtdblock/0': No space left on device
  1025+0 records in
  1024+0 records out

IOW, it dies after 4M.  is this a limit imposed by the ramdisk limit
in the kernel configuration?  is this a configurable parameter at
module load time?  thanks for any pointers.

rday