Re: [PATCH 3/3] mtd/nand : workaround for Freescale FCM to support large-page Nand chip

On 12/14/2011 10:59 PM, Li Yang wrote:

The limitation of the proposed bad block marker migration is that you
need to make sure the migration is done and only done once.  If it is
done more than once, the factory bad block marker is totally messed
up.  It requires a complex mechanism to automatically guarantee the
migration is only done once, and it still won't be 100% safe.

I would suggest we use a much easier compromise that we form the BBT
base on the factory bad block marker on first use of the flash, and
after that the factory bad block marker is dropped.  We just relies on
the BBT for information about bad blocks.  Although by doing so we
can't regenerate the BBT again,  as there is mirror for the BBT I
don't think we have too much risk.

I have corrupted the BBT too often during development (e.g. a bug makes
all accesses fail, so the upper layers decide to mark everything bad) to
be comfortable with this.

Elsewhere in the thread I suggested a way to let the marker be in either
the bbt or in a dedicated block, depending on whether it's a development
situation where the BBT needs to be erasable.

-Scott