Messages in this thread | | | Date | Thu, 15 Dec 2011 11:32:40 -0600 | From | Scott Wood <> | Subject | Re: [PATCH 3/3] mtd/nand : workaround for Freescale FCM to support large-page Nand chip |
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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
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