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IDProjectCategoryView StatusLast Update
0002166UBootNAND-FMDpublic2014-07-10 14:40
ReporterKeller Assigned To 
Status resolvedResolutionfixed 
Product Versionfsvybrid-V1.2 
Target Versionfsvybrid-V2.0Fixed in Versionfsvybrid-V2.0 
Summary0002166: Add support for block refreshing in U-Boot on Vybrid
DescriptionNAND flash blocks may also show read disturbances. That means if they are read many many times, some bits may toggle. These disturbances can always be recovered by refreshing the block, i.e. erasing and rewriting the data. NBootVyb does support block refreshing starting with version VN08. We should also do this in U-Boot, e.g. when reading the Linux kernel partition.
Additional InformationWe can use blocks 9 and 8 of the NAND flash as swap blocks. If there is no M4-image present, we can also use blocks 7 down to 2 as additional swap blocks if blocks 8 and 9 are marked as bad.

Make sure that our own block refreshing does not collide with UBIs handling of blocks with bit flips (scrubbing). For example UBI uses erase counters. If we rewrite a block behind the back of UBI, UBI will not update this counter, and can not do optimal wear leveling anymore.
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