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

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Date:	Thu, 18 Aug 2005 18:21:39 +0530
To: "Lennart Sorensen" <lsorense@csclub.uwaterloo.ca>

Dear all,

I have few updates in this issue.
I have attached the Images as well as the mount-log to this mail.
Please see the comments inline.

>If the partition starts at sector 57 and is 28743 sectors long, then
>that matches 28800 sectors total. No problem there.
>
>If on the other hand fdisk reports 28672 sectors total then there is a
>problem somewhere.

I think, fdisk it trying to portray that n/o cylinders 448. So, it also
takes care of displaying the relevant n/o sector & NO more or NO less.

>Well then you have to implement full partition support and present a
>seperate device for each partition in /dev so that mount can access
each
>partition.

I have implemented the partition support in the driver but some HOW I am
NOT able to get the driver working with all the sockets. It is just
working with the socket 0 and NO other socket.
I mean I am able to mount windows & linux formatted SD card with new
driver present from socket 0.

>> There is a partition table in the CAM formatted device & it looks
like
>> there is also a partition table in the win formatted device.
>> The details of there at offset 0x1BE are below.

I have an update on this.

I found some common things between the windows formatted SD & Linux
formatted SD.
I found that both of then do NOT have the partition table.
I found that both of them have FAT12 FS in the sector 0 starting at
offset 0.
Why? I am NOT able to guess.

For Windows formatted SD there is NO partition table at all.
I went on more R&D and tried to get to format the USB-Thumb drive.
Even that did NOT have a partition table.
It looks like windows treats all removable media device as devices with
NO partitions.

Even on Linux formatted SD there is NO partition table present.

Please have a look at the images I am attaching to this mail.
I have attached CAM-MS, WIN-Ms & Linux-MS first 512 byte length Images.
These are the Images of first 512 bytes of sector 0.
You can find the FS there on Lin & Win Images.

I have verified this by keeping some DEBUG messages in the FAT layer &
seeing what data is being passed to this fat_boot_sector structure when
mount call is issued.
I am also attaching those LOG messages. please Have a LOOK at them too &
you will have a fair understanding.

>That one looks more like random numbers. Maybe the partition entry
that
>it really uses is not number 1, but number 2 3 or 4, or no partition
>table at all.
I have verified it with fdisk -l -u /dev/tfa0
It has shown that it is the partition 0 & nothing else.

>Could you do dd if=/dev/sda bs=512 count=1 | xxd
Please see the Images-All-MS-512.tar.gz.

Regards,
Mukund Jampala

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• application/x-gzip attachment: Images-512-xxd-type.tar.gz

• application/x-gzip attachment: mount-logs-all.tar.gz

• Previous message: Con Kolivas: "Re: openafs is really faster on linux-2.4. than 2.6"
• Maybe in reply to: Mukund JB.: "The Linux FAT issue on SD Cards.. maintainer support please"
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• Reply: Lennart Sorensen: "Re: The Linux FAT issue on SD Cards.. maintainer support please"
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