Re: JFFS3 & performance

Artem B. Bityuckiy
2005-01-13T08:25:55Z

> I'm thinking the opposite conclusion. If I understand this correctly
> most CRC's on NOR are wasted effort. I don't claim to quite
> understand JFFS2 architecture yet but it seems to me the data CRC's
> are not needed for NOR, perhaps some of the other CRC's are not needed
> as well.
Hmm.

Suppose you have some device with NOR flash. That NOR flash stores your
files (flash file system works there, e.g. JFFS2). Suppose one of your
flash blocks become bad.

1. Scenario 1: You do not have any checksum or do not check it.
One of network-related library is loaded corrupted. It is loaded and start
sending private keys of your corporative clients to random addresses (if
your device is some router/switch etc).
Lots of nasty things may happen.

2. Secenario 2: Filesystem detects the CRC error, realizes that this error
is due to Media corruption. It prints the error message and returns -EIO
to the caller task which loads your library.

Yes, in both cases you put your device/NOR flash to the rubbish can, but
without checksum you may end up with much more serious consequences.

P.S. But JFFS2 does not behave as I described in scenario 2. I just
ignores the bad node, prints the error message, but still returns OK. So
you still might present private keys or another confidentional information
to potential plotters. But JFFS2 is not supposed to be ideal :-)

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.