Re: [microblaze-uclinux] FAT FS troubles

[David McCullough <davidm@xxxxxxxxxxxx>]

Jivin Rudolf Usselmann lays it down ...
> On Thu, 2005-06-02 at 21:54 +1000, David McCullough wrote:
> > 
> > The fat driver in uClinux is unchanged AFAICT from linux.
> 
> I compared it to the 2.6 kernel in my Fedora Core 3 release,
> and it is different, very different ...

Why would you compare it to the 2.6 source ?  This is a 2.4 kernel,
compare it to the 2.4 original,  they are the same.  I would expect
things to have changed between 2.4 and 2.6.

I diff'd the fat filesystem dires against the original 2.4.29 source
and they are the same.

> > I run the current uClinux kernel on my desktop and my MP3 player hooks
> > up fine so I am fairly sure it works ok ;-).
> > 
> > If the fat code is not working for you then I would suspect the
> > platform differences first.  Big-endian/little endian ?  Interface
> > problems ?  It's hard to say really.
> > 
> > Are you using the VFAT driver or just the FAT driver ?
> 
> Trust me I have dug very deep in to it. It is not an endianes
> problem. It reeds the MBR, and then goes to sector 233. There
> is NO reference to sector 233 in the MBR (or at least I have
> not found it).
> VFAT and FAT are identical up to all of this. VFAT includes
> long file names ... unwillingly I have been learning a lot
> about the structure of MBR, and FAT file system ...

I was trying to say that I run 2.4 on my desktop.  In fact the 2.4
kernel I run was compiled from the uClinux 2.4.x sources.

The FAT fs is working fine for me on my desktop (x86),  and I also
know that it is working in our products (ARM based).  All of which are
using the uClinux 2.4.x kernel.

So based on that it cannot be as broken as you suggest or it wouldn't
work at all on any platform.

> > Are you mounting the correct device ?  If thereare partitions
> > you need to mount the partition (ie., /dev/sad1 for partition 1),
> 
> Yes I am. I have a ton of debug messages, first from the low
> level SD/MMC interface routines, than from the block driver,
> and now I am adding stuff to the FAT FS driver as well.
> 
> Everything propagates correctly, and I can create "fake" cards
> that will work (single partition, single FAT).
> 
> Trust me there is something funny about the FAT Drier in uCLinux ...

I wouldn't be so sure just yet :-)

Cheers,
Davidm

-- 
David McCullough, davidm@snapgear.com  Ph:+61 7 34352815 http://www.SnapGear.com
Custom Embedded Solutions + Security   Fx:+61 7 38913630 http://www.uCdot.org
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