Messages in this thread | | | Subject | RE: The Linux FAT issue on SD Cards.. maintainer support please | Date | Thu, 18 Aug 2005 18:21:39 +0530 | From | "Mukund JB`." <> |
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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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