[U-Boot] Fat write problem

[Ruud Commandeur]

> -----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

> Cheers
>   Detlev
> 
> [1] http://www.denx.de/wiki/view/U-Boot/TooBigPatches
> 
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