Below is a copy of postings 1st March 2013 to FreeBSD then copied to NetBSD,
click on either to read any follow up.

Source code src/sbin/fsck_msdos/boot.c

FreeBSD/sbin/fsck_msdosfs/boot.c
NetBSD/sbin/fsck_msdos/boot.c
I have not checked a bunch of other OS's (BSD & Android) found by metager.de.
debian.org doesn't seem to have src/ components to remote browse ? (just complete OS to boot or install), Feel free to mail me a URL if I missed something.

To: hackers@@@freebsd.org
cc: gdt@@@NetBSD, paulp@@@uts.amdahl.com, rnordier@@@FreeBSD.org,
    Tom Rhodes <trhodes@@@FreeBSD.org>
Subject: sbin/fsck_msdosfs does not handle media with 2K blocks
From: "Julian H. Stacey" <jhs@@@berklix.com>
Date: Fri, 01 Mar 2013 01:45:03 +0100

Hi hackers@@@freebsd.org
cc: gdt@@@NetBSD, paulp@@@uts.amdahl.com    (< grep @ src/sbin/fsck_msdosfs/*.c)
cc: rnordier@@@FreeBSD.org          (< man newfs_msdos)
cc: Tom Rhodes <trhodes@@@FreeBSD.org>    (< man 5 msdosfs>

sbin/fsck_msdosfs (FreeBSD 9.1-RELEASE) fails on 2K block media,
media in this case, an mp3 player:  http://www.berklix.com/~jhs/txt/sigmatel/

sysctl kern.geom.debugflags=16
        kern.geom.debugflags: 16 -> 16

/sbin/fsck_msdosfs /dev/da0s1
            ** /dev/da0s1
    could not read boot block (Invalid argument)

devd.conf:
    "vendor" "0x066f"; "product" "0x8000"; "devclass" "0x00";
    "devsubclass" "0x00"; "intclass" "0x08"; "intsubclass"
    "0x06"; "intprotocol" "0x50" ; "release" "0x1001";

/sys/dev/usb/usbdevs: vendor SIGMATEL         0x066f  Sigmatel

dd if=/dev/da0   bs=2k of=da0   # 242304+0 records  496238592 bytes
dd if=/dev/da0s1 bs=2k of=da0s1 # 242256+0 records  496140288 bytes
echo "2048 242304 * p" | dc #           496238592
echo "2048 242256 * p" | dc #           496140288

fdisk /dev/da0
        cylinders=118 heads=64 sectors/track=32 (2048 blks/cyl)
        Media sector size is 2048
        Warning: BIOS sector numbering starts with sector 1
        Information from DOS bootblock is:
        The data for partition 1 is:
        sysid 6 (0x06),(Primary DOS, 16 bit FAT (>= 32MB))
            start 48, size 242256 (473 Meg), flag 80 (active)
                beg: cyl 0/ head 1/ sector 1;
                end: cyl 630/ head 7/ sector 48

( I think this unit's FS got corrupted. Possibly as part of media error ?
  This unit (when not USB connected, but powered on battery as a
  player, flashed its LCD display on & off, (same warning as to also
  indicate a low battery) whereas other units of same type with
  same battery powered up OK, & battery is OK, so player is probably
  also seeing a bad FS. )

I tried this:
    sysctl kern.geom.debugflags=16
    dd if=/dev/da0s1 bs=2k of=image
    mdconfig -a -t vnode -f image
    /sbin/fsck_msdosfs -y /dev/md2
        ** /dev/md2
        ** Phase 1 - Read and Compare FATs
        ** Phase 2 - Check Cluster Chains
        ** Phase 3 - Checking Directories
        /audio has entries after end of directory
        Extend? yes
        /audio has entries after end of directory
        Extend? yes
        long filename record cluster start != 0
        Invalid long filename entry for volume label
        Remove? yes
        ** Phase 4 - Checking for Lost Files
        139 files, 60280 free (7535 clusters)
        ***** FILE SYSTEM WAS MODIFIED *****
    ... Repeating fsck above, shows the same errors above ...
    newfs_msdos -F 16 -S 2048 /dev/md2
        newfs_msdos: Cannot get number of sectors per track,
            Operation not supported
        newfs_msdos: Cannot get number of heads,
            Operation not supported
        newfs_msdos: trim 21 sectors to adjust to a multiple of 63
        /dev/md2: 242192 sectors in 15137 FAT16 clusters
             (32768 bytes/cluster)
        BytesPerSec=2048 SecPerClust=16 ResSectors=1 FATs=2
            RootDirEnts=512 Media=0xf0 FATsecs=15 SecPerTrack=63
            Heads=16 HiddenSecs=0 HugeSectors=242235
    /sbin/fsck_msdosfs -y /dev/md2
        ** /dev/md2
        ** Phase 1 - Read and Compare FATs
        ** Phase 2 - Check Cluster Chains
        ** Phase 3 - Checking Directories
        ** Phase 4 - Checking for Lost Files
        1 files, 484384 free (15137 clusters)
    mount -t msdosfs /dev/md2 /mnt
    cp SETTINGS.DAT /mnt
    umount /mnt
    mdconfig -d -u 2
    dd if=image bs=2k of=/dev/da0s1
        dd: /dev/da0s1: Input/output error
        80+0 records in 79+0 records out
        161792 bytes transferred in 32.715037 secs (4945 bytes/sec)
    ... Remove & Reinsert & waited for devd & unmounted after auto-mount...
    Repeated dd & same error.
    ... Remove & Reinsert & wait for devd automount
    ls /usb/sigmatel    ... it has the new empty FS with SETTINGS.DAT
    ... but still the LCD flashes
    fdisk -B /dev/da0
        fdisk: /boot/mbr: length must be a multiple of sector size
    cat /boot/mbr /boot/mbr /boot/mbr /boot/mbr > /boot/mbr2k
    fdisk -B -b /boot/mbr2k /dev/da0
        Should we write new partition table? [n] y
    ... still the LCD flashes
    fdisk -i /dev/da0
    fdisk -u /dev/da0
    ( Not Tried: newfs_msdos with -s 512 to see if the Sigmatel chipset
        will play it, but not much point as fdisk says 2K ... )

So it seems this particular unit has a problem (that other units
of same manufacture here do not have). I can't think what else to try ?

It seems I discovered a limitation in FreeBSD (while doing the above):
    We should hack various sources to [also?] allow R/W of 2K
    media blocks , eg inc. here:
    /usr/src/sbin/fsck_msdosfs/
    dosfs.h:
        #define DOSBOOTBLOCKSIZE 512
    boot.c:
        readboot(int dosfs, struct bootblock *boot)
        {
        u_char block[DOSBOOTBLOCKSIZE];
        if (read(dosfs, block, sizeof block) != sizeof block) {
            perror("could not read boot block");
    Who might best hack those sources ?
    Maybe someone since 1997 Wolfgang Solfrank & 1995 Martin Husemann
    be interested?

Note another Odys player MP X30 V Multimedia Player, (vendor=0x10d6, product=0x1101 in devd.conf ) does not use 2048 but 512, (so not all mp3 players use 2048 (as someone speculated they might), (though Cdroms & DVDs use 2048 though)).

Top Of Page

Review of MP3 (& WAV) player, USB Vendor 0x066f, Product 0x8000

0x066f = Sigmatel

http://www.berklix.com/~jhs/txt/sigmatel/

By Julian H. Stacey - Index of other texts.

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2K Media Blocks Are A Problem for BSD fsck_msdosfs

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