[U-Boot] Fat write problem

[Ruud Commandeur]

> -----Oorspronkelijk bericht-----
> Van: Ruud Commandeur 
> Verzonden: vrijdag 17 januari 2014 16:50
> Aan: 'Detlev Zundel'
> CC: U-Boot list
> Onderwerp: RE: [U-Boot] Fat write problem
> 
>  
> 
> > -----Oorspronkelijk bericht-----
> > Van: Detlev Zundel [mailto:dzu at denx.de] 
> > Verzonden: vrijdag 17 januari 2014 15:59
> > Aan: Ruud Commandeur
> > CC: U-Boot list
> > Onderwerp: Re: [U-Boot] Fat write problem
> > 
> > Hi Ruud,
> > 
> > > This week I decided to do some further research and testing 
> > regarding
> > > this problem.
> > > With the image I had from the previous time, I could immediately
> > > reproduce it and
> > > by adding more and more debug prints, I tried to find the 
> > cause. Sofar,
> > > I have not
> > > succeeded in this yet.
> > >
> > > However: later on I started testing with a freshly 
> > formatted drive (32
> > > MB FAT partition)
> > > and kept repeating the fatwrite command:
> > >
> > > fatwrite mmc 0:1 42000000 test-x 200
> > >
> > > where x runs from 1, 2,3 and further. And this way I could 
> > reproduce it
> > > quite easily.
> > > Writing always fails for the 32nd file. This is with the partition
> > > formatted with a 512 byte
> > > sector size and a cluster size of 4. If the cluster size is 
> > 1 (formatted
> > > by Windows),
> > > it already fails at the 8th file.
> > >
> > > If I create a subdirectory (from Linux) with already 24 
> > files in it, I
> > > can still write 29 files
> > > and it fails at number 30. Also, if earlier files were 
> > deleted from the
> > > root-directory, they
> > > still count in the total number of files here.
> > >
> > > If I take out the card where u-boot fails to write new 
> files, I can
> > > still add new files from
> > > my PC with Linux or Windows.
> > >
> > > I tested with both long and short filenames (same result), VFAT is
> > > enabled.
> > >
> > > I hope this gives you all some more information about this 
> > problem and
> > > perhaps it is even a
> > > known problem (limited number of files in the root 
> > directory?). I know
> > > it is voor FAT16, but
> > > that was 512 entries if I am correct.
> > 
> > Thanks for the extensive research into this problem.  For people to
> > help, I think the barrier of reproducing the problem is "somewhat
> > high", so it occurred to me if you can help setup a very 
> easy test for
> > people to work on.  Would you be able to generate a small 
> > image that one
> > can dd to a mmc card and then immediately provoke the error?  If you
> > don't have any hosting space, as a last resort I'd be fine 
> for you to
> > put it on our wiki [1].
> > 
> Hi Detlev,
> 
> Thanks for your response. Finally I get some ;-)
> 
> I can look for creating some image, but I don't think it is 
> that hard to
> reproduce (now I think to know what causes it). Either use 32 
> times the
> fatwrite command (using the cmd history and increment the 
> x-nr each time)
> or just copy up to 31 files to the root of the FAT partition 
> by using the host
> machine and place the SD-card back on the targe device running u-boot.
> 
> Hope this makes it easy enough, otherwise I will be glad to 
> hear from you.
> 
> N.B. All this was with a FAT16 partition. If I use FAT32, I 
> have no such
> problem! At least not for 45 files up till now...
> 
> Regards,
> 
> Ruud

Hi Detlev (and others),

Just to be absolutely sure, I did a new attempt.

Created 32 MB FAT16 (type 06) partition with fdisk on
my SD-Card (1st parttion).
Formatted as FAT16, 4 sectors per cluster:

"sudo mkfs.vfat -v -n IPCAN -F 16 -s 4 /dev/sdf1"

Created 30 files on this mounted partition:

"for i in {1..30}; do touch /media/IPCAN/test-$i; done"

Plugged the SD-card into my EVK running u-boot and
started fatwrite testing:

fatwrite mmc 0:1 42000000 test-31
writing test-31
0 bytes written
CLB IP-CAN U-Boot > fatwrite mmc 0:1 42000000 test-32
writing test-32
MMC: block number 0x1002006 exceeds max(0x746000)
error: overflow occurs
error: overflow occurs
...
...

And the error is there and will remain there for any further attempts.
So it doesn't matter how and where the files were created, and what
size the files are, adding files >= 32 jut fails for FAT16.

Note that also "test-16" is missing when doing a "fatls mmc 0:1". The
file can be read though when doing a fatload for this file. This is
probably some other problem, but could be related.

For now, I will continue using FAT32. If any problems would arise there
I will post them.

Regards,

Ruud

> 
> > Cheers
> >   Detlev
> > 
> > [1] http://www.denx.de/wiki/view/U-Boot/TooBigPatches
> > 
> > -- 
> > Golden rule #12:   When the comments do not match the code, 
> > they probably are
> > both wrong. -- Steven Rostedt 
> > <1300126962.9910.128.camel at gandalf.stny.rr.com>
> > --
> > DENX Software Engineering GmbH,      MD: Wolfgang Denk & 
> Detlev Zundel
> > HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 
> Groebenzell, Germany
> > Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: 
> dzu at denx.de
> >