Data integrity check after UBIFORMAT? Bad image sequence number error.

[t kevin]

Hi Richard

Thanks for the reply. See inline comments below.

2015-06-09 16:20 GMT+08:00 Richard Weinberger <richard.weinberger at gmail.com>:
> On Tue, Jun 9, 2015 at 10:02 AM, t kevin <kevint324 at gmail.com> wrote:
>> Hi,
>>
>> We are using kernel 2.6.36 and mtd-util-1.5.1 on our box.
>> During system upgrade, very very occasionally ( 1 in 100, maybe? ) I
>> get this error at ubiattach after ubiformat.
>>
>> [ 1632.520000] UBI: attaching mtd8 to ubi0
>> [ 1632.520000] UBI: physical eraseblock size: 131072 bytes (128 KiB)
>> [ 1632.530000] UBI: logical eraseblock size: 126976 bytes
>> [ 1632.530000] UBI: smallest flash I/O unit: 2048
>> [ 1632.540000] UBI: sub-page size: 512
>> [ 1632.540000] UBI: VID header offset: 2048 (aligned 2048)
>> [ 1632.550000] UBI: data offset: 4096
>> [ 1633.190000] UBI error: process_eb: bad image sequence number
>> 559476870 in PEB 635, expected 139654706
>>
>> I understand ubiformat generate a random sequence number and write the
>> sequence number to all PEB. So it seems an expected sequence number
>> somehow is not written into nand flash correctly.
>
> Are you sure about that?
> Can it be that 559476870 is the seq number of the old image and the
> new one is too small?
> This is one of the main reasons why we have that number, such that
> UBI can detect a partial written image.
>
I don't really know what "559476870" is. We don't track image sequence
number : (

>> So I changed my upgrade sequence like below
>>
>> ubiformat ubi.img /dev/mtdx
>> ubiattach /dev/mtdx
>>
>> if [ "$?" != "0" ]
>>     #do ubiformat again
>>     ubiformat ubi.img /dev/mtdx
>
> You format it while it is attached?
>

I'll do re-format only when ubiattach returns fail and then I know
there is something wrong during ubiformat. So by that time it's not
attached.

>> My question are,
>> 1. What could possibly be wrong that caused the ubiformat fail?
>
> It can be a faulty MTD driver, a usage error, everything.
>
>> 2. Is there a way to verify the data integrity after a UBIFORMAT
>> process? Something like "mtd verify" function.
>
> I fear the answer is "no".
>

As I mentioned, the error is very rare, but it did happen multiple
times. So we are considering data integrity check.

> Thanks,
> //richard