John Valdes wrote:

>On Tue, Feb 20, 2001 at 02:35:14PM -0600, John Valdes wrote:
>> On Mon, Feb 19, 2001 at 02:00:43PM -0800, Daniel Lamblin wrote:
>> > I have a 40Gb drive I wish to commonly share accross all my occasionally 
>booted
>> > OSes, namely Mac OS 9, BeOS, GNU/Linux (ppc) debian, NetBSD!(yay)
>> [...]
>> > I want to have long filename (really long, not just 32 chars) supported on
>> > most if not all the OSes when reading and writing to that disk.
>> 
>> As much as it pains me to say it, I would guess that a VFAT32
>> filesystem is probably your only choice.  NetBSD & Linux can read this
>> FS.  MacOS can too, although I've only tried it on removable media
>> (floppy, zip, etc); don't know if MacOS can access VFAT32 on a
>> partition.  I'm guessing BeOS can handle VFAT32, though perhaps not on
>> ppc.
>
>Thinking about this more, I think there'll be one problem; while all
>the OSes may support VFAT32, I don't think the Apple partition map
>supports this filesystem type (or more properly, OSes which know how
>to read Apple partition maps probably don't expect to find VFAT32
>filesystems on a disk that has an Apple partition map).
>
>There's also the related problem of creating a VFAT32 partition on a
>disk w/ an Apple partition map; newfs_msdos can create the actual
>filesystem, but AFAIK, there's no utility to mark an Apple partition
>as being of type VFAT32.

There's a paper that was written a couple of years ago by an Apple 
Engineer which describes how to make a disk useable under both MacOS and 
MSDOS/Windows.  If you search around the internet you may still be able 
to find it.  Basically the disk mapping schemes used on both systems can 
occupy the same block on disk (Block 0).  Then all that needs to be done 
is to reserve the area used by MSDOS as a non-standard Apple partition 
type in the Apple Disk Partition Map and do the same for the Apple used 
areas in the fdisk map.  One could map a common part of the disk in both 
maps, although I'm not quite sure how the systems would deal with the 
byte order of the data in that area.  Making the disk bootable on both 
systems may be a bit of a strech though.

-bob