Re: [SLUG] R/O Floppies

From: Ian C. Blenke (icblenke@nks.net)
Date: Thu Oct 10 2002 - 12:34:07 EDT


On Wed, 2002-10-09 at 23:16, Paul M Foster wrote:
> On Wed, Sep 11, 2002 at 08:52:06AM -0400, Ian C. Blenke wrote:
>
> > On Tue, 2002-09-10 at 21:19, Paul M Foster wrote:
> > > On Tue, Sep 10, 2002 at 07:39:15PM -0400, Ronan Heffernan wrote:
> > >
> > > > Paul M Foster wrote:
> > > > >I've got a Debian 3.0 system (2.4.18) that's telling me plainly R/W ext2
> > > > >floppies are read only. Anyone know how to convince the system to mount
> > > > >the floppy R/W regardless of what it thinks? Or some other way to get
> > > > >around the problem?
> > > > >
> > > > >Paul
> > > > >
> > > >
> > > > Paul-
> > > > Are the little plastic Write-protect sliders in the closed position?
> > > > With modern floppy drives, there is no software way around that.
> > > >
> > > > --ronan
> > > >
> > >
> > > Umm, that's why I said "plainly R/W"-- the tabs are in the R/W position;
> > > I never mess with them. And no, the fstab doesn't say the floppy is R/O.
> > > And I'd really rather not resort to a power cycle. ;-} Sometimes issues
> > > like this go away after the machine has had a chance to sit overnight;
> > > some sort of timeout issue, I imagine. But I was hoping for something
> > > more direct. I believe I've read that the floppy drivers in Linux are
> > > buggy. That's true as far as I'm concerned, because I've seen other
> > > issues with them before, and with some regularity.
> >
> > So, with the floppy RW notch in the RW position, you're still unable to
> > get a RW filesystem using:
> >
> > # mount -t ext2 -o rw /dev/fd0 /mnt
> >
> > This fails for you? What does your mount table show?
> >
> > # cat /proc/mounts
> >
> > The mount command likes to look at and use /etc/mtab, which sometimes
> > gets out of sync with how the kernel thinks things are mounted.
> >
> > Mounting a floppy read-write works just fine for me.
> >
> > How about this:
> >
> > # dd if=/dev/fd0 of=/tmp/floppy.img bs=18k
> > # mount -o loop -t ext2 /tmp/floppy.img /mnt
> > {copy things to /mnt}
> > # umount /mnt
> > # dd if=/tmp/floppy.img of=/dev/fd0 bs=18k
> >
> > This would help narrow down the problem a bit. This should narrow down
> > wether it's a device permissions problem (/dev/fd0), a failed floppy RW
> > sensor, a filesystem permissions problem (/mnt after mounted), or a
> > kernel bug. Is there anything in your kernel log?
> >
> > # dmesg | tail
> >
> > No problems mounting ext2 floppies RW here. I run debian 3.0 pretty much
> > everywhere these days. Sparc included ;)
>
> Okay, it happened again. This time, I had been popping some R/O DOS
> floppies in and out, and then wanted to copy something onto a R/W ext2
> floppy. The system thinks the R/W floppy is R/O. I followed the above
> steps.
>
> Plain mount with the -o rw switch doesn't work. Says the drive is R/O. I
> can dd off the floppy content and loop mount it, etc. But copying it
> back to the floppy via dd encountered the R/O problem. /proc/mounts and
> /etc/mtab both show the floppy as R/O, despite the fact that physically
> it is not. The kernel (and other logs) simply show that the floppy is
> R/O, nothing else. Tried ext2fs, and same thing. Cash money says that
> if I reboot, the problem will disappear. I'd sure like a way to poke a
> value somewhere in the /proc hierarchy and change this status, but I
> don't think there's a way.
>
> Any other suggestions are welcome.

You could dd read, but not dd write?

This sounds like you have a flakey floppy rw/ro sensor. I've had them go
bad on me before as well.

If a reboot fixes it, then you've found a very interesting kernel bug.

There are also a number of well known flakey floppy controllers out
there that they've had to hack around in the kernel. I personally append
"floppy=daring" to my kernel options and chalk any errors up to bad
media ;)

- Ian C. Blenke <icblenke@nks.net> <ian@blenke.com>
http://ian.blenke.com



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