On 01/27/2012 04:46 PM, Scott Wood wrote: > On 01/26/2012 11:34 AM, Peter Barada wrote: >> On 01/26/2012 12:27 PM, Scott Wood wrote: >>> Why are two copies insufficient for that? >> Two copies are sufficient, if none of the blocks ever go bad. >> >> To simplify things, suppose the environment is the same size as a block >> and you have only two blocks (and two copies) to hold the environment. >> If one block goes bad then there is a window between when the one >> remaining block is erased and written with the environment that if power >> fails then there is no environment in NAND. > It seems unlikely, but possible I guess. Currently I don't think we > dynamically mark blocks bad at all in U-Boot, except in things like ubi > and yaffs. I'm probalby being paranoid, but from what I've seen, if it can fail, odds are it will.
I can add code to mark the blocks bad if the erase/write fails. >> To solve this I can crank up the number of blocks to three which allows >> one block to go bad and still at all times have one good copy of the >> environment in NAND. But looking at writeenv(), it stops as soon as >> either nand_write fails, or one copy of the environment is written. So >> it could make sense to modify writeenv to write as many copies of the >> environment that fit into CONFIG_ENV_RANGE, and have readenv read out >> copies and verify them until it finds one good one. > This isn't what CONFIG_ENV_RANGE is about. I think it would make more > sense to change REDUND to support more than two copies (each with their > own range). Its somewhere in the middle. REDUND give you two copies. ENV_RANGE gives you one copy but allows it to live in the first good block. Modifying either way is going to affect units in the field. But I'll give it a whirl. > Probably better to never update the environment in the field -- source a > script in an ubi partition instead. Proper planning will save one from having to update the environment in the field, but I'm sure it happens. I just figured I'd try to make sure that nothing bad happens when people do... -- Peter Barada peter.bar...@logicpd.com _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
