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Xref: sserve comp.unix.aix:23030 comp.unix.aux:9588 comp.unix.bsd:12077 comp.unix.cray:802 comp.unix.sys5.r4:3008 Newsgroups: comp.unix.aix,comp.unix.aux,comp.unix.bsd,comp.unix.cray,comp.unix.sys5.r4,cmp.unix.xenix Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!agate!dog.ee.lbl.gov!hellgate.utah.edu!fcom.cc.utah.edu!cs.weber.edu!terry From: terry@cs.weber.edu (A Wizard of Earth C) Subject: Re: Support for 4.2BSD Fast File System Message-ID: <1993Jun7.232802.8354@fcom.cc.utah.edu> Keywords: bsd filesystem Sender: news@fcom.cc.utah.edu Organization: Weber State University (Ogden, UT) References: <C815MC.10I@queernet.org> <1ukgtd$gmr@mail.fwi.uva.nl> <C823vt.7up@queernet.org> Distribution: inet Date: Mon, 7 Jun 93 23:28:02 GMT Lines: 36 In article <C823vt.7up@queernet.org> rogerk@queernet.org (Roger B.A. Klorese) writes: >This is a special case; Sun decided to keep their on-disk format >identical. You cannot, however, move a filesystem image between >SVR4/Intel and Solaris 2, or SVR4/Intel and SunOS, or even (no byte >order issues) Mips RISCos and either Sun operating system. The >exact on-disk layouts differ somewhat. It's a byte order, device driver, and volume header issue. The disklabel must be recognized by the kernel on the machine for the disk partitions to parse properly. Once this is correctly accomplished, /dev entries will refer to specific partitions on the disk. In order to actually mount the disk, the mount op in the vfsops struct for the file system has to be hacked to recognize what information is in the volume label/volinfo struct. Sun has added "clean bit" fields to the disk to speed fsck's, among other things, so this requires a change to the decode. After that, it's pure FFS as far as the layout goes. The majority of differences in SunOS are code structure; the differences in Solaris are SMP changes, and Sun won't document those to anybody without a source license (and I mean *anybody*). The byte-order issues will chew you up on the disklabel, volume info, and the on disk inodes and superblocks -- basically, anywhere data objects or structures are written to disk. There are also alignment issues which have to be taken care of to correctly decode the structures, since the padding will vary from machine to machine. *BUT* it *is* possible to mount FFS disks across architectures if you are willing to eat the conversion overhead. Terry Lambert terry@icarus.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.