[Om2008.12] Adding swap space can stop app crashes

Carsten Haitzler (The Rasterman) raster at rasterman.com
Sat Jan 17 13:32:14 CET 2009

On Sat, 17 Jan 2009 17:29:12 +0530 Kishore <kitts.mailinglists at gmail.com>

> > 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)    raster at rasterman.com

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