Re: Having trouble with a UBI filesystem

[Ron Bowes <ron@xxxxxxxxxxxxxxxxx>]

Hi Emil and Richard,

Thanks for the quick responses!

Email - It is indeed a NAND flash chip. I did some googling about OOB
data, and that looks very promising. I'll have to read up some more,
but I'm guessing this is why I'm seeing a UBI header every 0x21000
bytes instead of the more normal 0x20000 bytes - there's 0x1000 bytes
of OOB data in each block. I'll do some more reading and see if I can
eliminate that.

Richard - yeah, the tool hasn't worked well so far, but I was hoping
it'd work well enough to avoid reading kernel code. I'm definitely out
of my element!

I tried using mtdram and ubiattach, but I couldn't get it to work
right. It always complained that the data started at 0x1000 instead of
0x840, and I couldn't figure out why:

[ 5828.047122] ubi0 error: validate_ec_hdr: bad data offset 4096, expected 2112
[ 5828.047499] ubi0 error: validate_ec_hdr: bad EC header
[ 5828.047817] Erase counter header dump:
[ 5828.048099]  magic          0x55424923
[ 5828.048377]  version        1
[ 5828.048643]  ec             0
[ 5828.048911]  vid_hdr_offset 2048
[ 5828.049197]  data_offset    4096
[ 5828.049469]  image_seq      606494591
[ 5828.049747]  hdr_crc        0x9116275f

I traced my way through ubiattach, but it looks like this is a
kernel-level thing. That's when I started looking at the Python tool.

Emil's comment about OOB data might be the issue, though. Other parts
of the memory dump were unexpected sizes, as well, so I think OOB data
is probably the culprit.

Thanks!

On Thu, Jan 3, 2019 at 12:25 PM Richard Weinberger
<richard.weinberger@xxxxxxxxx> wrote:
>
> On Thu, Jan 3, 2019 at 8:52 PM Ron Bowes <ron@xxxxxxxxxxxxxxxxx> wrote:
> > folks) and ubi-reader (from https://github.com/jrspruitt/ubi_reader).
>
> Last time I looked at ubi_reader I was not satisfied at all.
> So I'd not recommend it. But this was over a year ago.
>
> > Can anybody help me understand what I'm looking at? And how I can
> > either mount or extract this?
>
> Find the correct flash parameters and load the image into mtdram
> or nandsim to mount it.
>
> --
> Thanks,
> //richard

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