Can you really write a jffs2 image with nandwrite?
pgrayson at realmsys.com
Tue Mar 1 13:11:51 EST 2005
On Tue, 2005-03-01 at 03:47 +0100, Thomas Gleixner wrote:
> On Mon, 2005-02-28 at 19:14 -0700, Peter Grayson wrote:
> > From reading the mkfs.jffs2 code, it seems that mkfs.jffs2 has no
> > concept of out-of-bounds data. Consequently, it appears that the
> > nandwrite expects to find out-of-bounds data immediately after the in-
> > bounds data for every page. I have looked at the bits of the jffs2 image
> > produced by mkfs.jffs2 and I can see that it does not really produce out
> > of bounds data.
> nandwrite does not expect oob data for jffs2 images.
But it appears nandwrite can accept oob data. It does have the --oob
option and when this option is set nandwrite reads the oob data from the
image and does an ioctl() to the mtd character device to write it.
> > Below is the mkfs.jffs2 command line I am using. I have tried many other
> > combinations of options, but they do not yield appreciably different
> > results.
> > mkfs.jffs2
> > --pagesize=2048 \
> > --eraseblock=128 \
> This one if definitely wrong. You meant 128kiB or 131072.
mkfs.jffs2 interprets "128" as "128KiB", but I should be more explicit.
> > --pad \
> > --output=image.jffs2 \
> > --compression-mode none \
> Why do you switch off compression ?
I have made images both ways -- in this case I was looking at hex dumps
of images and sans compression the dumps were a little more human-
readable. In the end, I do want to use compression.
> > --no-cleanmarkers \
> > --big-endian \
> > --squash \
> > --verbose \
> > --root=$ROOT_DIR
> > When I try using this image with "nandwrite -j", the image appears to be
> > written successfully, but when I try to mount the new filesystem, mount
> > fails with the following error message:
> > mount: Mounting /dev/mtdblock0 on /mnt failed: Invalid argument
> Did you ?
> mount -t jffs2 /dev/mtdblock0 /mnt
> > If I try to use "nandwrite -j -o", nandwrite complains about the image
> > not being aligned:
> JFFS2 has no oob data. nandwrite -j is correct.
> > Is there something obvious I am missing? I have read the FAQ at:
> > http://www.linux-mtd.infradead.org/tech/faq.html
> I'm happy that somebody actually read it :)
> > so I know that the working theory is that this should work, but it is
> > not working for me. Has anyone else had a similar experience?
> Before using nandwrite please erase the flash with
> flash_eraseall -j /dev/mtd0 .
This was definitely useful. I am now able to write images with
nandwrite. Here are the magic steps I am taking:
1) mkfs.jffs2 \
2) flash_eraseall -j /dev/mtd0
3) nandwrite /dev/mtd0 image.jffs2
With mkfs.jffs2, I had some confusion about the pagesize option. I was
thinking that it corresponded to the NAND pagesize, but that is not
correct, it sets the jffs2 filesystem page size.
With nandwrite, the -j option causes things to not work. This was a
great stumbling block for me. It proved to be critical to _not_ use the
-j (or -o) option with nandwrite. This is in direct conflict with
instructions in the FAQ.
Thanks for the help, this definitely got me jumpstarted.
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