On Sat, 17 Jan 2009 17:29:12 +0530 Kishore <kitts.mailingli...@gmail.com> babbled:
> > even openmoko's wiki: > > > > http://wiki.openmoko.org/wiki/Booting_from_SD > > > > SD cards are supposed to support wear leveling, but this can not be > > guaranteed for all vendors. > > > > :) > > > > i can keep hunting down more references - but its meant to be part of the > > spec. cards should do it - some may do it better than others (ie name > > brands - cost more, lifetime warranties), and some el-cheapo ones may skip > > it to cut costs. > > Thanks for the information. With such widespread use of USB flash drives > which are really cheap and of large capacities I guess the technology has > gotten cheaper. I recollect that the concept was called flash translation > layer or something like that. Anyway, it also justifies the higher price paid > for the bigger brands. A good reason for me to recommend the bigger brands > over the many other cheaper ones in the market! :) as such built-in flash (nand - not sd-on-chip) doesn't have this. thus jffs2, ubifs and freinds are needed to move the wear-levelling into os/cpu space. you may still be thinking of that. i know years ago i was doing an arm based "webpad" project .. of course os on flash. during development we weren't using jffs2 - using ext2... in the space of a few months of development and fiddling with the fs - we burnt through the write cycle limit. but this was long ago when write-cycles limits were 1/100th of what they are now. and it was silly using ext2 - but never got to changing it to jffs2 etc. before the project was cancelled. :) thank god several prototypes were floating about :) so back then - if you did ext2/3 on a raw flash (mtd) device. woe betide ye who did. these days on sd etc. it's "taken care of" ... or SHOULD be. but quality... is what you pay for :) -- ------------- Codito, ergo sum - "I code, therefore I am" -------------- The Rasterman (Carsten Haitzler) ras...@rasterman.com _______________________________________________ Openmoko community mailing list community@lists.openmoko.org http://lists.openmoko.org/mailman/listinfo/community