Re: [PARPORT] Phase change filesystem


grant@torque.net
Wed, 1 Jul 1998 07:08:58 -0400 (EDT)


> I managed to install a PANASONIC LF-1500 PD-drive (Parallel port) under
> Linux (Kernel 2.0.33, paride-driver from
> http://www.torque.net/parport/paride.html) - at least the CD-ROM-part!
> (drivers and protocols: paride, pcd, epat)
>
> When I try to mount it as a PD-drive (drivers and protocols: paride, pf,
> epat)
> with a medium partitioned and formatted under NT4, a get a filesystem-error.
>
> In a HowTo (Opticals) I read something about incompatible PD-filesystems -
> so my question is: is there any possibility to change data between NT4, W95,
> DOS and linux via PD-media?

I think the concept of "incompatible PD-filesystems" is a bit misleading.
There is no special filesystem for PD disks, nor is this even a filesystem
issue at all.

The problem is that there are no standards about partitioning "superfloppy"
media. When I built the 'pf' driver, it appeared that the convention
was that ATAPI disks would _not_ be partitioned.

It would appear that your NT drivers have decided to use partition tables.

I am not sure what the correct long-term solution for this is going to
be, but in the meantime we can work around the problem, I believe.

As a first step, please try

        fdisk /dev/pf0

On an NT formatted disk. Print the partition table and see if it
appears to make sense. If so, switch to expert mode and print the table
there. Under the "start" column you'll see the starting sector number
of the partition. Record this number, you will need it in the next step.

Next, assuming that you have a recent version of mtools installed, add
the following line to your /etc/mtools.conf

        drive p: file="/dev/pf0" offset=XXX

where XXX is the byte offset of the start of the file system. Take the
sector offset from the expert partition table and multiply by 512 to get
the byte offset.

This should allow you to use mtools to read and write the PD disk as
drive p:. Of course, you can change the drive letter if p is busy, or
you prefer something else.

If this works, please send me all the details. I can easily add a
similar offset construct to the pf driver without causing our own
incompatiblity problems. Such a feature would tide you over until we
determine a way to resolve the larger problem.

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Grant R. Guenther grant@torque.net
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