How do I access floppies under Linux?

(written by Haidinger Walter)

By mounting. First you need a mount-point, i.e. a directory under which you can access your floppy. You can chose an arbitrary name, I use /df0 through /df3 (and /pc0 to /pc3 respectively) because I'm used to these names from AmigaOS.

Create the directories. e.g.:

mkdir /df0 mkdir /any-name-will-do mkdir /ados/df0 mkdir /ados/pc0 ...

Next, check if you have the proper device nodes: Type:

ls -l /dev | grep "^b.* 2, [0-7]"

For me, that lists:

brw-r--r-- 1 root wheel 2, 0 Mar 31 18:16 df0 brw-r--r-- 1 root wheel 2, 1 Mar 31 18:16 df1 brw-r--r-- 1 root wheel 2, 2 Mar 31 18:16 df2 brw-r--r-- 1 root wheel 2, 3 Mar 31 18:16 df3 brw-r----- 1 root 25 2, 0 Jun 22 1996 fd0- brw-r----- 1 root 25 2, 4 Feb 26 1994 fd0d360 brw-r----- 1 root 25 2, 4 Jun 22 1996 fd0d360- brw-r----- 1 root 25 2, 5 Jun 22 1996 fd1d360 brw-r--r-- 1 root wheel 2, 4 Apr 4 11:49 mfd0 brw-r--r-- 1 root wheel 2, 5 Apr 4 11:49 mfd1 brw-r--r-- 1 root wheel 2, 6 Apr 4 11:49 mfd2 brw-r--r-- 1 root wheel 2, 7 Apr 4 11:49 mfd3 brw-r--r-- 1 root wheel 2, 4 Mar 31 18:03 pc0 brw-r--r-- 1 root wheel 2, 5 Mar 31 18:16 pc1 brw-r--r-- 1 root wheel 2, 6 Apr 8 12:03 pc2 brw-r--r-- 1 root wheel 2, 7 Apr 8 12:03 pc3 ^ ^ ^ =09 ^^^ block-device major minor node-name=20

Do not worry if you have other results. What do you need to know?

• Floppies are block devices.

• Floppies have major device number 2.

• Under Linux/m68k, the minor device numbers are as follows:

  0 to 3 ... Amiga drives 0 to 3 (i.e. df0 to df3) 4 to 7 ... MS-DOS drives 0 to 3 (i.e. pc0 to pc3)

  Like under AmigaOS with CrossDOS, drive 0 is a single physical unit. Note that this is different from Linux/i386. You can verify this by reading Documentation/devices.txt of the kernel source. The nodes fd* above are remnants of a Intel configuration; only the major/minor numbers count, not the assigned name!

Now create the device-nodes:

mknod /dev/df0 b 2 0 mknod /dev/df1 b 2 1 mknod /dev/df2 b 2 2 mknod /dev/df3 b 2 3 mknod /dev/pc0 b 2 4 mknod /dev/pc1 b 2 5 mknod /dev/pc2 b 2 6 mknod /dev/pc3 b 2 7

Set the desired permissions with the chmod command.

Remember, the names (here: df0 and pc0) are arbitrary. However, on Intel Linux systems, the floppy nodes are named /dev/fd*. To access devices under different node-names, just create symlinks. e.g:

ln -sf /dev/pc0 /dev/fd0 ln -sf /dev/pc1 /dev/fd1 ln -sf /dev/pc2 /dev/fd2 ln -sf /dev/pc3 /dev/fd3

Now, MS-DOS drive 0 can be accessed by /dev/fd0 as well as /dev/pc0. If you want /dev/fd0 to be an Amiga drive, link it to /dev/df0 instead. Of course, this are just examples from my configuration. You can choose other names if you like.

After having mount-point and device-node, you can mount your floppy.

For an AmigaOS disk in drive 0:

mount -t affs /dev/df0 /df0 ls /df0 ... umount /df0

For a MS-DOS disk in drive 1:

mount -t msdos /dev/pc1 /pc1 ls /pc0 ... umount /pc0

Warnings:

• Only mount if floppy already in drive and

• you must not remove the floppy before umount'ing it!

You can also put this into your /etc/fstab file. Mine looks like this:

# device mountpoint type options freq passno # -------------------------------------------------------------------------- # Amiga Floppies /dev/df0 /ados/df0 affs defaults,noauto,noexec 0 2 /dev/df1 /ados/df1 affs defaults,noauto,noexec 0 2 /dev/df2 /ados/df2 affs defaults,noauto,noexec 0 2 /dev/df3 /ados/df3 affs defaults,noauto,noexec 0 2 # # MS-DOS Floppies /dev/pc0 /ados/pc0 msdos defaults,noauto,noexec 0 2 /dev/pc1 /ados/pc1 msdos defaults,noauto,noexec 0 2 /dev/pc2 /ados/pc2 msdos defaults,noauto,noexec 0 2 /dev/pc3 /ados/pc3 msdos defaults,noauto,noexec 0 2

I'm not quite sure about the freq/passno fields. Do a "man 5 fstab" and a "man 8 mount" for more info.

Other topics about floppies: