Corrupted UBIFS, bad CRC

[Artem Bityutskiy]

On Mon, 2012-01-16 at 00:18 -0800, Karsten Jeppesen wrote:
> Hi Artem,
> 
> Of course I can. Anything I can do to help.
> 
> I put it on one of my outside servers and I put as well the /dev/mtd4 as the ubi0_0 you asked for:
> 
> <http://download.gnist.skov.com/corrupt_mtd4_20120116.img>
> and
> <http://download.gnist.skov.com/ubi0_0_20120116.img>

Thanks.

I've taken a look by using mtdram. You have a strange corruption: 144
bytes of 0xFFs, then 32 bytes of zeroes, and then all 0xFFs. This looks
like some oddity of your NOR flash.

My theory is that your flash has write buffer and its size is 256 or
larger.

Anyway, first of all - start with pulling the latest ubifs-v2.6.32 tree
- I've added few changes there very recently which fix UBI/UBIFS
debugging messages.

Also, please, enable UIBFS debugging compilation option.

From now on I assume you have done this. Also I assume that you are
aware that you need to look at dmesg to see all the UBIFS messages.
There is some test in the MTD web site which explains this.


Next: if I hack UBIFS like this:

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 6c3fb5a..58a49e7 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -691,6 +691,8 @@ static int io_init(struct ubi_device *ubi)
        ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);
 
        ubi->max_write_size = ubi->mtd->writebufsize;
+       ubi->max_write_size = 256;
+
        /*
         * Maximum write size has to be greater or equivalent to min. I/O
         * size, and be multiple of min. I/O size.

Then I can mount your image successfully.

What is 'mtd->writebufsize' in your setup? You need to find out the
right size and teach your driver to report it correctly.

UBI reports max_write_size when you attach the MTD device. E.g., with
mtdram I have the following:

[493058.328443] UBI DBG (pid 18798): io_init: min_io_size      1
[493058.328444] UBI DBG (pid 18798): io_init: max_write_size   64

With my hack it is 256, of course. The mtdram module which I use
hard-codes it to 64.

-- 
Best Regards,
Artem Bityutskiy
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