Date: Tue, 20 Jun 2006 22:08:28 -0500 From: Eric Anderson <anderson@centtech.com> To: matt@genesi-usa.com Cc: freebsd-fs@freebsd.org Subject: Re: On-disk format of UFS/UFS2 (for firmware implementation) Message-ID: <4498B82C.2010600@centtech.com> In-Reply-To: <00bf01c69481$57a793d0$99dfdfdf@bakuhatsu.net> References: <00bf01c69481$57a793d0$99dfdfdf@bakuhatsu.net>
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Matt Sealey wrote: >> You probably are looking for this paper: >> >> A Fast File System for UNIX (1984) >> http://citeseer.ist.psu.edu/12920.html > > We have this implemented already in the firmware. > > However this does not help reading UFS2 (64-bit numbers, extents etc. > and myriad other things to look out for). I like the "Design and Implementation of the FreeBSD 5.2..." book. It covers what you need, plus more that you won't need. The best documentation is the .h files I think, but you aren't interested in those. >> Sleuthkit contains code to read many file systems and its >> code may assist in extracting the design of FFS. >> http://www.sleuthkit.org/ >> >> There has been work on flash file systems for BSD, a quick >> search may turn up something useful. > > Why a flash filesystem? For different reasons - mostly for embedded systems builders who use a real OS (like FreeBSD) but want to make their flash last a while. > Our OpenFirmware has disk support, it pushes them into the device > tree and you can load/boot any file on any supported filesystem (this > includes IDE, SCSI, USB disks..) > > We just want to parse and use UFS filesystems, i.e. the modern ones > that OpenBSD (UFS) and FreeBSD and NetBSD (UFS2) use. FFS isn't the > same thing, as I am told by hundreds of articles... at least there are > some differences which I have found hard to find the documentation on. > > In theory we should be able to implement the entire gamut in one > filesystem support package, the same way the Linux ufs driver does, > by adapting the "1984 FFS" driver. > > For that we need to know what we are doing.. :) > > The Sleuthkit guy seems to have written a book which may be very > useful to us (if we order it..) http://www.digital-evidence.org/fsfa/ > and this is more like what we are looking for. Source code as > documentation is really the last resort when it comes to supporting > things as it makes for very hard and expensive work. > Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------
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