Subject: Re: accessing non-DOS diskette formats
To: Christian Groessler <>
From: Manuel Bouyer <>
List: netbsd-users
Date: 01/10/2002 10:33:23
please post this to tech-kern for discussion and review, and submit it as
change request using send-pr.

On Thu, Jan 10, 2002 at 02:29:25AM +0100, Christian Groessler wrote:
> Hi,
> our fdformat(1) programm is very flexible in supporting non-standard
> diskette layouts. One can specify all relevant parameters describing a
> diskette format (except FM - MFM, but FM anyway won't work on 99% of
> the systems).
> But there is no way to access a non-conforming diskette layout, there
> are only some formats available, which are PC (DOS) specific (see
> fdc(4)).
> I had the need to access some other format, so I did some changes to
> support those formats (which are available when formatting the disk)
> also later when accessing the disk.
> I created a fdparm utility (derived from the fdformat(1) utility)
> which can be used to set the diskette parameters.
> Then I modified the fd.c driver (sys/dev/isa/fd.c) to provide a
> "persistent device".  The old fd.c driver allowed all the changes
> in parameters which fdformat provides, but after closing the device
> all changes were gone. This did not appear very useful to me. My
> "persistent device" remembers the changes to the configuration until
> it's changed again.
> This way the fdparm tool can set the configuration and then disks of
> this layout can used very easily.
> I used the "h" device (e.g. /dev/fd0h) to be the persistent device,
> maybe this is not wanted and the # of minor devices should be upped
> from 8 to 16 for the floppy devices? Is this feasable? Then there
> would be room for some other default layouts (see fdc(4)) and we
> could use 2 or more "persistent" settable layouts.
> Anyway, my changes are on
>  or
> ...
> Is there a chance that this can get integrated?
> regards,
> chris
Manuel Bouyer, LIP6, Universite Paris VI. 
     NetBSD: 23 ans d'experience feront toujours la difference