RE: The Linux FAT issue on SD Cards.. maintainer support please

From: Mukund JB.
Date: Fri Aug 12 2005 - 09:31:51 EST


Dear Marc,

I have doubt about the driver?
I do NOT support the partitions in my driver. I mean I have implemented
it as alloc_disk(1) i.e. 0 partitions.
Is this what is creating the HAVOC to mount my SD card?
Do I need to support the partitions in my driver to support mounting SD
cards formatted in DIGITAL CAMERAS?(clarity needed)

I have an update on the CAM formatted SD.

SECTOR-0 Description:
Bytes 0 446
512
Details |- MB code -| - partition + signature |
Table

I dumped the 1st sector of SD when formatted on
1) CAM &
2) Windows
Yes, the partition table exists on both.
The only protruding difference I find is the Master Boot Code. Can you
comment on the Master Boot Code?

I tried copying the windows SD first 446 bytes to CAM SD first 446
bytes.
I am able to mount but I am loosing the data.

I have attached the files. Please have a look at them

Cluster-0.txt - First 16 Blocks of the device
Phy-Cam-57-sector.txt - 57th sector of the device (claimed FAT
in
Partition table)

Thanks & Regards,
Mukund Jampala

>-----Original Message-----
>From: Marc Singer [mailto:elf@xxxxxxxxx]
>Sent: Thursday, August 11, 2005 11:26 AM
>To: Mukund JB.
>Cc: hirofumi@xxxxxxxxxxxxxxxxxx; linux-kernel-Mailing-list
>Subject: Re: The Linux FAT issue on SD Cards.. maintainer support
please
>
>On Thu, Aug 11, 2005 at 10:57:14AM +0530, Mukund JB. wrote:
>> Dear all,
>>
>> I am Linux driver programmer.
>>
>> I have a FAT12 issue on my SD cards. I have got these addresses from
the
>> fs-lists as the maintainer support mail IDs for FAT-FS.
>>
>> I am using the 2.6.10 kernel, X86 like systems.
>>
>> I am NOT able to mount the Camera formatted FAT12 filesystem on my
linux
>> BOX. SD card is of size 16MB. At the same time I am able to mount the
SD
>> cards formatted in windows & linux.
>>
>> I have identified fat_fill_super() in fs/fat/inode.c file as the
>> function that reads the super block of as MS-DOS FS.
>>
>> To debug, I have rebuilt my kernel 2.6.10 inserting some debug
messages
>> in the FS sub-system to know what data is coming into "struct
>> fat_boot_sector *b" structure in fs/fat/inode.c file after sb_bread()
>> call.
>>
>> I believe that this data in the "struct fat_boot_sector *b" should be
>> FAT12 information.
>>
>> On the camera formatted SD that is NOT mounting I have found this
>> structure to be all '0' till total_sectors variable (relevant till
here
>> on - FAT12).
>>
>> Will you please verify if there & tell me if the problem is in the
FAT
>> sub-system.
>
>Alternatively, you can dump the first block of the device/partition.
>From that, you can determine if there is a partition table. In any
>case, you can read the first block of the partition (or whole device)
>and get the filesystem parameter block.
>
>It should be easy from there to determine if the data can be
>recognized as FAT.

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