From: dennisf@denix.elk.miles.com (Dennis Flaherty) Subject: Re: mount and COHERENT file systems Date: Mon, 9 Aug 1993 20:25:27 GMT
In article <piggy.744882423@newsroom.utas.edu.au> piggy@hilbert.maths.utas.edu.au (La Monte Yarroll) writes:
> torvalds@klaava.Helsinki.FI (Linus Torvalds) writes:
>
> >In article <CBEvMM.21r@hip-hop.suvl.ca.us> chris@hip-hop.suvl.ca.us (Chris Mason) writes:
> >>Recently I tried to mount a coherent formated disk onto a linux system.
> >>I got a error telling me the
> >>magic numbers did not add up. Does this
> >>confirm my fears that unix standard is an oxymoron? Is it true that
> >>every unix has it's own special file system?
Yes, but Linux isn't just another unix... ;-)
> >Not every unix, but yes, they do vary a lot.. Coherent seems to have
> >one of the older sysv filesystems (512-byte original sysv fs?), so it's
> >compatible with some of the "normal" i386 unix systems, but generally
> >you can't count on swapping disks between different unixes (and not
> >always even between the "same" unix - byte-order problems may make
> >otherwise similar disk layouts incomprehensible even to a unix that
> >otherwise is the same but runs on another machine type).
>
> One of the distinctive features of the COHERENT file system is that
> byte-order is not a problem--you can read/write COHERENT file systems
> on any kind of machine running COHERENT, regardless of the internal
> byte-order. This is the origin of the infamous byte-order
> cannonicalization patent held by MWC.
Didn't SUN think of this first and put it in NFS? Real original, MWC.
Which big-endian cpu does Coherent run on?
> >> Whats the work around?
>
> >Under linux, you could try out the "sysvfs" patches found on
> >sunsite.unc.edu, pub/Linux/development/Filesystems/sysv (or something
> >very close to that) which should give you a kernel that can read
> >coherent disks (I haven't tested it personally as I don't even have any
> >disks to test with).
>
> This won't work.
But it does work!
Linus is (surprise, surprise) correct; the COHERENT fs is so similar to
the Missed 'em V fs that the same fs drivers work for both the sysvfs
and COHERENT fs. You mount -t COHERENT, and the slight differences for
COHERENT are switched.
> You actually need to write a handler for the
> COHERENT filesystem. This code may be an OK starting place since the
> filesystem is superficially similar to the original V7 512byte file
> system.
If the changes are more than superficial, I'd like to ask you to help me
test it: make a COHERENT fs on a 3.5" floppy, put whatever you want on
it, umount, use dd to copy it all to a file, compress, uuencode, and
mail it to me. I'll show you.
Soon we'll be mounting COHERENT filesystems and running its binaries. :-)
--
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