Re: FreeBSD's embedded agenda
"Andrew Atrens" <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.small |
|---|---|
| Message-ID | <[email protected]> |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Olivier, Olivier Gautherot wrote: > Hi Andrew! > > >>[...] >> >>>The reason Flash Adaptation Layers came about in the first place >>>is that W95 didn't support anything but FAT. >> >> >>Hmm. I was thinking about partitioning the problem actually. Make flash >>look like a disk and then you can put any filesystem on it that you >>want. Seems a heck of a lot simpler .. and I'm not sure if I see any >>drawbacks to doing it that way ... > > > The drawback is the following: what would happen if you had an application > opening-writing-closing a file in /var/log on a regular basis? The block > would decay with time, with chances that your log even gets corrupted. > That's why Flash drivers have to spread write accesses across the device > (what FFS doesn't naturally do). Also, there is a constraint regarding > the changes allowed: on NAND flash, you can write a 0 on a bit but have > to erase the full block to write a 1 back. > > Don't forget that Flash doesn't suffer from mechanical delays so there > is no harm in fragmenting the filesystem: this would be another feature. > > My cent worth ;-) Yes, exactly... that's precisely what 'wear-leveling' is meant to do .. I think I mentioned wear-leveling further back in the email chain .. Yes, you definitely want wear-leveling. The debate is whether the filesystem knows about it, versus it being managed by a lower level 'driver'. Andrew. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFEdfln8It2CaCdeMwRAo/kAJ0R6Wx5XGXscCaiJPKXcAMH2hfkYwCfeOtL s6pOk3K0jcjboPbO/pPnlSM= =95q/ -----END PGP SIGNATURE----- _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-small To unsubscribe, send any mail to "[email protected]"