Re: Bug#823881: dosfstools: mmd fails right after mkfs.msdos (sectors/tracks mismatch)
On Wed, May 11, 2016 at 05:32:17AM +0200, Cyril Brulebois wrote:
> [ Poke Steve. ]
>
> Andreas Bombe <aeb@debian.org> (2016-05-11):
> > On Tue, May 10, 2016 at 02:15:42PM +0200, Andreas Bombe wrote:
> > > Since 416 blocks is a rather odd value, the default is used and that has
> > > changed. I think mtools is overzealous in checking those values and
> > > refusing to work. Still, it probably makes sense to use 64/32 as the
> > > default for smaller filesystem sizes (up to 512 MB possibly) and I'll
> > > prepare a version that implements this.
> >
> > Uploading this now.
> >
> > As far as I'm concerned, I consider this an aesthetic change. There is
> > still no guarantee that the total number of sectors is a multiple of
> > sectors per track. It just happens to work with the current values.
>
> Steve → we probably don't want to be hardcoding such things in so many
> places right? 3 calls in src:debian-installer, plus debian-cd, and maybe
> others?
In my opinion all that effort to placate mtools is the quintessential
tail wagging the dog. I don't know the installer environment, but
disabling those checks in /etc/mtools.conf or ~/.mtoolsrc would be the
way to go.
> > If you want to make this robust, you'll either have to explicitly
> > specify matched size/sectors/heads on the command line to mkfs.msdos or
> > disable the bogus mtools check like everyone else does when encountering
> > that error.
>
> Thanks for your input and the proposed change.
>
> I think Steven mentioned (when we first diagnosed this) a possibly
> bogus/overzealous check on mtools side as well. You seem to agree. So,
> if this check is bogus, why not fix it/remove it upstream then?
Upstream for mtools does not seem to be particularly active, last
release was in 2013.
The problem with this check is that it is at best a heuristic. Total
sectors not being a multiple of sectors per track means that some
sectors in the last track are left unused. And nobody would just waste
some of the scarce space on a floppy, right?
That might indicate something is fishy, but it's not an actual error.
It's definitely meaningless in the linear addressing case of larger
disks where the 255/63 dummy values are used.
> > Seriously, searching for that error message in your favorite search
> > engine will give you pages upon pages of hits, all of them describing
> > how to turn it off.
>
> Seriously, I read the man^Winfo page and implemented a workaround in
> src:debian-installer already.
I didn't mean to come across as sarcastic or whatever, I just wanted to
note how there are so many people affected by this while I couldn't find
anyone treating it as anything but a nuisance error. So yeah, the
consensus seems to be it's a bogus check.
Andreas
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