Messages in this thread | | | Date | Thu, 18 Aug 2005 13:26:53 -0400 | Subject | Re: The Linux FAT issue on SD Cards.. maintainer support please | From | (Lennart Sorensen) |
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On Thu, Aug 18, 2005 at 06:21:39PM +0530, Mukund JB`. wrote: > 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. > > 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. > > 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. > > 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.
If you don't use fdisk to create a partition on the card, then you won't have one. If you mkdosfs on /dev/tfa0 then you loose the partition table and get a filesystem on just the whole disk. If you do it with /dev/tfa0p1 then you do it on the first partition which would then have the FAT filesystem starting at the offset of the first partition (as it should).
> 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.
That is right. Although I believe if windows sees one with a partition table it will just use the first valid partition table entry it finds and ignore the rest.
> 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. > > I have verified it with fdisk -l -u /dev/tfa0 > It has shown that it is the partition 0 & nothing else. > > Please see the Images-All-MS-512.tar.gz.
Well to mount anything without a partition table, you would mount the whole device (/dev/tfa0) and to mount one with a partition table on it, you would mount /dev/tfa0p1 or tfa0p4 or whichever partition it is.
Zip drives used to be the same way. Some were formated with 1 partition (usually 1 or 4) and some had no partition table at all and used the whole disk for the filesystem. I always had a /zip and /zip4 mount point I used depending on the particular disk I was looking at.
Len Sorensen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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