can not mount a large FAT32 filesystem

[Peter Edwards]

On 9/28/05, Scott Long <scottl at samsco.org> wrote:
> Mikhail Teterin wrote:
> > Thank you very much, Peter!
> >
> > Your patch below makes the card "mountable" and usable. I'm copying
> > my photos right now.
> >
> > I think, this should be merged into 6.0 -- these cards are a popular
> > item... Thanks, again!
> >
> >       -mi
> >
> > Index: msdosfs_vfsops.c
> > ===================================================================
> > RCS file: /nfs/dyson/export/home/petere/freebsd-cvs/cvs/FreeBSD/src/sys/fs/msdosfs/msdosfs_vfsops.c,v
> > retrieving revision 1.144
> > diff -u -r1.144 msdosfs_vfsops.c
> > --- msdosfs_vfsops.c  24 Mar 2005 07:36:13 -0000      1.144
> > +++ msdosfs_vfsops.c  27 Sep 2005 09:40:19 -0000
> > @@ -512,9 +512,7 @@
> >  #endif       /* !MSDOSFS_LARGE */
> >
> >       if (pmp->pm_RootDirEnts == 0) {
> > -             if (bsp->bs710.bsBootSectSig2 != BOOTSIG2
> > -                 || bsp->bs710.bsBootSectSig3 != BOOTSIG3
> > -                 || pmp->pm_Sectors
> > +             if (pmp->pm_Sectors
> >                   || pmp->pm_FATsecs
> >                   || getushort(b710->bpbFSVers)) {
> >                       error = EINVAL;
>
> Might this be an attempt by the manufacturer to avoid the potential
> patent litigation from using msdosfs?  I.e. create a slightly
> non-conformant filesystem so that it can't claim to explicitely be
> msdosfs/vfat/fat32/whatever, thereby avoiding the patents on those
> technologies?
>
> Since these checks are done after other magic number checks, it's likely
> safe.  I'm fine with it going into RELENG_6 once it hass been committed
> to HEAD.
>
> Scott

As I said, I can't see any reference to this signature in the
"official" specification for the FAT boot-sector anyway, so I doubt
you could claim it wasn't a FAT boot-sector based on that change
anyway. I imagine the've just relaxed the spec, and new
implementations don't have the baggage of 20 years of evolving
operating systems and disk technology lying about :-)

I'll commit it this evening.