[PATCH] nandwrite: add --nobad to write bad blocks

[Mike Frysinger]

On Wed, Sep 29, 2010 at 08:59, Artem Bityutskiy wrote:
> On Wed, 2010-09-29 at 13:35 +1000, Iwo Mergler wrote:
>> The upshot of this is that blocks are marked as bad by the
>> manufacturer based on corner case testing. Like erasing at
>> high temperature / low voltage and reading back at low
>> temperature / high voltage. The manufacturer can also
>> access pads on the naked die that are not connected to pins
>> during packaging.
>
> Is only about letting you write to bad eraseblocks, not about erasing
> them. I assumed this cannot be used for marking bad eraseblocks as good
> back. The kernel does not have any protection against writing to bad
> eraseblocks, so I do not see why Mike cannot have this option.

correct on all points :)

> But speaking about erasing bad eraseblocks, which we also discussed, I
> think you have a good point - we should probably distinguish between
> factory-marked bad eraseblocks and user-marked. AFAIR, the OOB marker
> for them was even different, or in BBT, do not really remember.
>
> We probably can allow erasing user-marked bad eraseblocks and unmarking
> them. But we probably should not allow erasing factory-marked bad
> eraseblocks. But again, I'm not sure if it is possible to do, did not
> really think about this.

i think you're correct here too.  i havent seen any indication that
factory-marked bad blocks are distinguished in any way from
user-marked bad blocks.  either in the software BBT or in the OOB
layout.
-mike