markus reichelt wrote: > * emin ak <[EMAIL PROTECTED]> wrote: > > I need to encrypt a jffs2/mtd formatted flash filesystem for an > > embedded device, Normally using a loopback interface (cryptoloop, > > DM-crypt or loop-aes) solves this problem but they are not well > > known on journalling file systems (like jffs2) because of cached > > write etc.. Also I could'nt find any guideline for encrypting > > fikesystem on a flash. > > device-backed loops are ok, file-based once aren't. The cache issue > you talk about concerns writing caches of HDDs f.e., I haven't seen a > flash device with writing cache. However, in most cases writing cache > can be turned off.
Flash devices behave differently than hard disks. If I remember correcly, bits can be flipped in one direction (set or reset) without erasing whole block, but flipping a bit in reverse direction requires that whole block be erased first. If jffs2 takes advantage of this one-direction-bit-flipping, then adding encryption layer between jffs2 and flash device makes it completely different game that is guaranteed to require lots of flash block erases that wears down the device much faster than expected. -- Jari Ruusu 1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9 DB 1D EB E3 24 0E A9 DD - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
