State of UBI

Josh Boyer jwboyer at
Sun Sep 10 08:35:34 EDT 2006

On 9/10/06, David Woodhouse <dwmw2 at> wrote:
> On Sun, 2006-09-10 at 12:47 +0400, dedekind wrote:
> > Well, what you've listed is not what UBI itself needs:
> > 1. "double page writes on NAND" - it needs MTD changes and zero UBI changes.
> > 2. JFFS2 integration also requires zero changes in UBI (as long as it is
> > sane).
> I need to properly review UBI but I've been fairly busy on OLPC hardware
> bringup so I haven't found the time yet.
> Preliminary impressions are that I'm concerned by the amount of code --
> it's _huge_. And I'm concerned by the fact that it doesn't just provide
> MTD devices. I had envisaged that it would be fairly much akin to
> another partitioning layer, perhaps requiring a few extra methods to be
> added to the mtd_info. But it's a new type of device all of its own, and
> requires far more to be changed in MTD users (like JFFS2, FTL, etc.)
> than I had imagined.

Gluebi was intended to provide this translation from UBI device to MTD
device.  I don't think that is a bad approach myself.  Either way
though, JFFS2 needs to be taught not to do wear-leveling or erasing on
a UBI device.

I'll see if I can scrounge up the latest gluebi patches on Monday.  I
doubt they'll appear on this list otherwise.


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