Re: Pass -EUCLEN to userspace?

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Fri, 22 Apr 2016 17:48:35 +0200
Richard Weinberger <richard@nod.at> wrote:

> Sascha, Boris,
> 
> Am 22.04.2016 um 17:28 schrieb Boris Brezillon:
> >>> I am currently working on a program similar to ubihealthd, just for raw
> >>> mtd pages, not UBI. Basically I want to find out in userspace if my Nand needs
> >>> scrubbing. Is it possible somehow to get this information in userspace?
> >>
> >> Actually we discussed that a year ago with Richard. I told him that we
> >> should put the read/write/erase statistics at the MTD level so that
> >> other MTD users (including userspace programs) could use the same infra
> >> for non-UBI partitions (I need that for the UBOOT and SPL partitions).
> >>
> >> My suggestion was to store those information at the MTD level, and let
> >> UBI implement its own scrubbing layer on top of that, but Richard
> >> decided to go for a simpler approach for its first implementation.
> 
> Yeah, I did a first implementation on UBI layer as it had everything we need
> and I didn't want to replicate UBI at MTD level.
> Another reason is that we were not sure how sophisticated ubihealthd needs to be.
> 
> Sasha, what exactly is your use case and why is the UBI approach not sufficient for you?
> On Linux MTD access should only happen through UBI and UBOOT/SPL partitions stay untouched.

Fair enough. So all we'll need is a way to retrieve the maximum number
of bitflips for a given block, so that the userspace deamon can
periodically read the SPL and bootloader blocks and decide to scrub
those blocks if the number of bitflips exceed the threshold.


-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com