[G5] FAT32 formatting in OS X?

[Brian Durant]

I am planning to install Linux on an extra internal HD and as I
understand there are some problems with mounting HFS + vvolumes from
Linux, I was wondering if there is a way I can create a FAT32
partition for sharing files between the two systems. I know this can
be done in Linux, but there is a problem that I quote below from an
e-mail that I found. So... the big question is if there is a way to
format FAT32 partitions from OS X?

Here is the e-mail:

"Date: Wed, 3 Apr 2002 11:27:59 +0100
To: debian-powerpc at lists.debian.org
Subject: Sharing disk space between MacOS X and Linux

Hi,

I spent a few hours figuring out how to do this so I thought I'd share the
results of my fiddling to save people time in the future.

I have an iBook2 on which I primarily run Linux. However, on occasion I reboot
into MacOS X -- primarily to watch a DVD or connect to the Internet using the
built-in 56K modem. For various reasons it is desirable to have a partition
which both operating systems can use (to exchange downloaded files, etc).

Originally I planned to have a 1.5Gb HFS+ or HFS partition shared between the
two. However, this didn't work out -- the hfsplus tools don't really "mount"
the partition into the kernel's VFS tree and the vanilla HFS driver has
crashed my kernel several times. So I scrapped this idea and the partition lay
fallow for a few months. A few days ago, however, I was away from my Ethernet
and wireless networks and urgently needed to download a large postscript file
to the Linux partition using the 56K modem, so I went looking for a solution.

It occurred to me that both OS X and Linux 2.4 have pretty solid support for
FAT32. I could reformat and use my 1.5Gb "shared" partition as FAT32 under
Linux quite happily using 'mkdosfs -F 32' and mounting it with the vfat
filesystem. Lovely. Indeed, I could mount the same partition under MacOS X
from the shell, however I couldn't persuade MacOS to automount it and make it
appear on my desktop, because OS X thought it was an HFS partition without a
correctly formatted HFS volume due to its type entry in the partition map.

Much fiddling later I discovered the solution: Mac OS X will discover and
mount the partition correctly as FAT32 if you set the partition type to the
magic string "DOS_FAT_32". In mac-fdisk, use the 'd' to delete your partition,
then use the 'C' (capital C!) option to create a new one covering exactly the
same sectors on the disk, then enter the type as "DOS_FAT_32". I partitioned
under Linux and then formatted under OS X using the Disk Tool in Utilities.

It works very well indeed for me. Under Linux the fstab entry looks like this:

/dev/hda10      /scratch        vfat    defaults,uid=500,gid=500    0 0


... and 'mac-fdisk -l' reports:

/dev/hda
        #                    type name                 length   base  
  ( size )  system
dump: name /dev/hda len 8
/dev/hda1     Apple_partition_map Apple                    63 @ 1     
  ( 31.5k)  Partition map
/dev/hda2          Apple_Driver43 Macintosh                54 @ 64    
  ( 27.0k)  Driver 4.3
/dev/hda3          Apple_Driver43 Macintosh                74 @ 118   
  ( 37.0k)  Driver 4.3
/dev/hda4        Apple_Driver_ATA Macintosh                54 @ 192   
  ( 27.0k)  Unknown
/dev/hda5        Apple_Driver_ATA Macintosh                74 @ 246   
  ( 37.0k)  Unknown
/dev/hda6          Apple_FWDriver Macintosh               200 @ 320   
  (100.0k)  Unknown
/dev/hda7      Apple_Driver_IOKit Macintosh               512 @ 520   
  (256.0k)  Unknown
/dev/hda8           Apple_Patches Patch Partition         512 @ 1032  
  (256.0k)  Unknown
/dev/hda9               Apple_HFS untitled            5120000 @ 1544  
  (  2.4G)  HFS
/dev/hda10             DOS_FAT_32 Scratch             3072000 @
5121544  (  1.5G)  Unknown
/dev/hda11        Apple_Bootstrap Bootstrap             65536 @
8193544  ( 32.0M)  NewWorld bootblock
/dev/hda12                   Swap Linux               2097152 @
8259080  (  1.0G)  Unknown
/dev/hda13        Apple_UNIX_SVR2 Linux              28713848 @
10356232 ( 13.7G)  Linux native

I'm very pleased with this. The only annoyance is that OS X insists on
labelling the disk icon "SCRATCH" and won't allow me to rename it to something
that isn't all-caps. Ho hum, can't have everything ;)

I'd be interested if anyone has solved this problem by a more elegant route
(preferably involving a "real" filesystem...)"

Cheers,

Brian