OOB Test fails

[Danesh Daroui]

Hi Boris,

I have one question and would appreciate if you can assist me with that. As I wrote we are using a Micron NAND 1GiB 3,3V 8-bit flash memory with UBIFS where we experience some problems. I am wondering whether there are specific drivers provided by vendor in this case or there are generic drivers with respect to the hardware architecture given to the Kernel that can be used as we probably did in this case? I have downloaded a driver package from Micron which is apparently written for our NAND flash memory but the driver uses lots of read/write functions which are platform dependent and not implemented in the driver which makes sense though.

Would you please advise and let us know if we are on the right track e.g. using the driver with the kernel or we need to find more specific driver so the problem that we face now can be related to incorrect driver?

Regards,

Danesh Daroui


-----Original Message-----
From: Boris Brezillon [mailto:boris.brezillon at free-electrons.com] 
Sent: den 27 oktober 2016 17:45
To: Steve deRosier <derosier at gmail.com>
Cc: Danesh Daroui <Danesh.Daroui at ascom.com>; linux-mtd at lists.infradead.org
Subject: Re: OOB Test fails

On Thu, 27 Oct 2016 09:34:07 +0200
Boris Brezillon <boris.brezillon at free-electrons.com> wrote:

> Hi Steve,
> 
> On Wed, 26 Oct 2016 09:16:42 -0700
> Steve deRosier <derosier at gmail.com> wrote:
> 
> > Hi Danesh,
> > 
> > 
> > On Wed, Oct 26, 2016 at 9:07 AM, Danesh Daroui <Danesh.Daroui at ascom.com> wrote:  
> > > Hello all,
> > >
> > > I have executed MTD tests against an unmounted MTD device which uses UBIFS. All MTD tests except OOB test is passed where the OOB test fails from time to time and from device to device. I have read here:
> > >
> > > http://www.linux-mtd.infradead.org/faq/ubi.html#L_why_no_oob
> > >
> > > that UBIFS does not use OOB area. Therefore wanted to ask if failing this test does not need that there is any problem in our system (both HW and SW/configuration) and we can safely ignore the results for this test.
> > >    
> > 
> > UBIFS doesn't use the OOB area, but your MTD driver most likely does.
> > We don't want UBI or UBIFS messing with the OOB area because your 
> > flash, NAND controller and the MTD driver will use that. Bad block 
> > markers are set in the OOB area by the manufacturer in most NAND 
> > flashes and your controller and MTD driver will store and use the 
> > bits in the OOB to do error correction.
> > 
> > So, in short - the OOB area does need to function correctly.  As to 
> > if and why the OOB test is or isn't working is a different issue and 
> > I have no input on that.  All that depends on your mix of flash, 
> > controller and driver.

My bad, I misread your sentence. I thought you we saying "the OOB area does *not* need to function correctly".

My apologies for this misunderstanding, it seems we're on the same page.