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

From: Mukund JB`. (mukundjb_at_esntechnologies.co.in)
Date: 08/18/05

  • Next message: Mukund JB`.: "RE: The Linux FAT issue on SD Cards.. maintainer support please" 
    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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  • Next message: Mukund JB`.: "RE: The Linux FAT issue on SD Cards.. maintainer support please"

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