Rob Austein wrote: > how to make better use of the keystore flash .. > We've talked about layering some kind of filesystem on top of the > flash, whether that filesystem be something that understands flash > wear leveling (eg, UFFS, YAFFS) or something that doesn't (eg, FATFS).
Wear leveling is important for NAND, but maybe not required for Alpha. > a filesystem per se may not really be appropriate here in any case: > what we really want is some kind of record storage .. > Peter Gutmann advised us to look at PKCS #15 Looking at it is good, using it not so much. Let's try to do better. > https://www.micron.com/~/media/documents/products/data-sheet/nor-flash/serial-nor/n25q/n25q_128mb_3v_65nm.pdf Wear leveling isn't quite as important on NOR. > So it occurred to me that if we really just need a record store, maybe > we should just write that. .. > not bother with a filesystem per se at all. ..except.. > subsector > chain multiple sub-sectors > a set of opaque attributes > an in-memory index > an in-memory bitvector > allocated > examining the flash at boot time > subsector to start with a few header fields > type code > indicating whether this sub-sector is pristine > distinguish between data under construction and data that was fully written > index structures > lookup > insertion or deletion > binary search > hash buckets / balanced trees .. > Comments? ..it sounds like you've just invented a file system. Look at UBI, and maybe also UBIFS, but at least UBI. Granted, UBI makes the most sense for NAND. //Peter _______________________________________________ Tech mailing list Tech@cryptech.is https://lists.cryptech.is/listinfo/tech
