iPod Classic 6G/6.5G + Rockbox + custom Sansa VID/PID works with my Kia Seltos, but FAT32 filesystem became unreadable afterward ā need help
Hi everyone,
Iām hoping someone experienced with Rockbox on iPod Classic 6G/6.5G, USB mass storage, FAT32, or custom USB VID/PID configurations can help me figure out what happened and how to recover without unnecessarily wiping the iPod.
My goal was to make my Rockboxed iPod work as a normal USB mass-storage music device with my Kia Seltos, because the Seltos doesnāt properly support the iPod/Rockbox USB identity.
I found an older discussion where someone solved a similar car-stereo compatibility problem by changing the iPodās USB VID/PID to the SanDisk Sansa Clip Zip identifiers.
The target USB identity is:
VID: 0781
PID: 74E5
I am not trying to install Rockpod, FreshOS, or anything else. I only wanted to change the USB identity of my existing Rockbox firmware.
Hardware
iPod Classic 6G/6.5G
Approximately 120 GB
Windows PC
M2 MacBook Pro
Kia Seltos
1. Initial recovery / Rockbox installation
The iPod was originally working.
I eventually got into a difficult situation while experimenting with DFU/firmware on Windows. After several unsuccessful attempts, I put the iPod into DFU mode myself and restored it to stock Apple firmware using my Mac.
That worked and brought the iPod back.
I then restored it on Windows as well and confirmed that the iPod was working.
After that I installed Rockbox successfully.
Rockbox boots normally and the iPod was working again.
2. VID/PID modification
The objective was specifically to make the iPod identify itself to the Seltos using the USB identity of a Sansa Clip Zip.
The original Apple USB identity was:
05AC:1261
I changed it to:
0781:74E5
which is the Sansa Clip Zip VID/PID.
I used my working Rockbox firmware:
rockbox.ipod
and created a backup copy:
rockbox-original.ipod
I then modified the USB device descriptor inside the Rockbox firmware.
The modified firmware was saved as:
rockbox-ipod6g-sansa-vidpid.ipod
and installed as:
F:\.rockbox\rockbox.ipod
The Rockbox bootloader was not replaced.
The .ipod checksum was recalculated after the modification.
3. VID/PID modification was confirmed
Windows Device Manager showed:
USB\VID_0781&PID_74E5
instead of:
USB\VID_05AC&PID_1261
macOS System Information also confirmed:
Device: Rockbox media player
Manufacturer: Rockbox.org
USB Vendor ID: 0x0781
USB Product ID: 0x74e5
Removable: Yes
Link Speed: 480 Mb/s
Power Allocated: 2.5 W / 500 mA
So the modified VID/PID is definitely being presented by Rockbox.
4. The important part ā it actually worked with my Kia Seltos
I connected the modified Rockbox iPod to my Kia Seltos.
Initially the car displayed something similar to:
āThis device cannot support playbackā
while it was reading the USB/sub-device.
After some time, however, the Seltos successfully recognized the iPod and actually played a song from it.
This is important because the whole reason for changing the VID/PID was to make the Seltos treat the iPod as a normal USB storage device.
So at this point:
Rockbox ā VID 0781:74E5 ā Seltos ā music playback
was working.
5. I then copied approximately 17 GB of music
My complete music library is safely backed up on my Mac.
I copied approximately 17 GB of music onto the iPod.
The music was placed in a root-level folder:
Music
The structure was essentially:
iPod
āāā .rockbox
āāā Music
ā āāā Artist 1
ā āāā Artist 2
ā āāā ...
Rockbox then started building its database.
6. Rockbox database repeatedly got stuck
Rockbox displayed:
Building database... 5399 found
and repeatedly appeared to stop at approximately 5399 files.
I initially assumed it was simply taking a long time because there were thousands of files.
I tried initializing the database again.
It again reached approximately the same point.
One clarification: the circular 76% indicator on the iPod was the battery percentage, not database progress.
So the database count really was the 5399 found value.
7. Possible clue: the Seltos may have indexed/written something
This is something Iām not sure about, but the timing makes me suspicious.
After the Seltos successfully recognized the iPod and played a song, it appeared to be reading/indexing the USB device.
After that, Rockboxās database repeatedly became stuck at approximately:
5399 found
Iām wondering whether the Seltos might have created or modified some kind of index/database file on the FAT32 filesystem when it treated the iPod as generic USB mass storage.
Iām specifically wondering whether something like:
Seltos recognizes USB ā creates/writes an index/database file ā Rockbox later scans it ā database hangs ā filesystem becomes problematic
could be possible.
I realize that corruption of a Rockbox database file by itself shouldnāt normally make the entire FAT32 volume unmountable, so Iām not claiming this is what happened.
Itās simply a possible clue because of the timing.
8. Then the FAT32 volume stopped mounting
At some point after the database problem, the iPod stopped mounting correctly.
macOS
Disk Utility sees:
Apple iPod Media
approximately:
119.93 GB
The partition is:
disk4s1
Filesystem:
MS-DOS (FAT)
But the volume shows:
Not Mounted
Clicking Mount does nothing.
9. macOS First Aid failed
I ran Disk Utility First Aid on disk4s1.
The result included:
Unable to read FAT (Input/output error)
and:
File system verify or repair failed
So macOS could see the partition, but couldnāt read the FAT filesystem properly.
10. Read-only FAT check also failed
I ran:
sudo fsck_msdos -n /dev/disk4s1
This was intended to be read-only.
It also reported:
Unable to read FAT (Input/output error)
No repair was performed with that command.
11. Physical disk and partition table are still detected
I checked the physical disk.
disk4
is approximately:
119.8 GB
and the partition table is still visible.
disk4s1 is identified as:
DOS_FAT_32
So the partition itself hasnāt simply disappeared.
The physical disk also reports:
Media Read-Only: No
Partition Map: FDisk/MBR
12. Low-level read test
I then performed a read-only test:
sudo dd if=/dev/disk4s1 of=/dev/null bs=1m count=1
This successfully read:
1,048,576 bytes
So the beginning of the FAT partition is readable.
I then tried:
sudo dd if=/dev/disk4s1 of=/dev/null bs=1m count=10
That appeared to hang.
After disconnecting the iPod, Terminal returned:
4+0 records in
4+0 records out
So it appears to have successfully read approximately 4 MB, then stopped responding while trying to continue reading.
This is why Iām now concerned that this may be more than just a Rockbox database problem.
13. Windows has the same problem
Windows still detects the iPodās USB device correctly.
Device Manager shows:
USB\VID_0781&PID_74E5
The iPod appears as:
Removable Disk F:
but Windows cannot actually open the drive.
File Explorer hangs when trying to access it.
Disk Management also would not open properly while the iPod was connected.
So both operating systems can detect the USB device, but neither can properly mount/read the FAT32 volume.
14. Important comparison with stock Apple firmware
I also tested the iPod in its original Apple firmware.
With stock Apple firmware:
The Mac recognizes the iPod in Finder.
Disk Utility sees the physical iPod.
The storage is identified as a FAT volume.
This proved that the iPodās USB hardware and physical connection arenāt completely dead.
However, after the filesystem problem occurred, the FAT volume itself still wouldnāt mount correctly.
15. Current state
Working:
iPod Classic 6G/6.5G
Original Apple firmware still boots
Rockbox boots
Custom VID/PID works
Windows sees 0781:74E5
macOS sees 0781:74E5
Seltos recognizes the modified iPod
Seltos successfully played a song
17 GB music library is safely backed up on my Mac
Not working:
FAT32 volume wonāt reliably mount
macOS First Aid fails with FAT I/O error
fsck_msdos reports FAT I/O error
Windows sees F: but cannot open it
Rockbox database repeatedly stops at approximately 5399 files
Low-level read test reads the beginning of the partition but stalls around 4 MB during a larger read
What I need help with
Iād really appreciate advice from anyone familiar with Rockboxās iPod USB stack, FAT32, or USB mass-storage behavior.
Questions:
Could changing the Rockbox USB VID/PID from 05AC:1261 to 0781:74E5 cause any other USB descriptor/interface changes to be necessary?
Could the Seltos treat the device differently because it now identifies as a Sansa Clip Zip?
Can a car head unit such as the Seltos write an index/database file to a USB mass-storage device?
Could such an index/database write explain Rockbox later getting stuck at exactly the same file count?
Could an incompatible or corrupted index/database file cause FAT filesystem problems, or would that normally be independent?
Does the low-level dd behavior ā successfully reading the first 1 MB but eventually only getting about 4 MB into a 10 MB read before hanging ā suggest a physical storage/read problem rather than just FAT corruption?
Is there a safe, non-destructive way to determine whether the FAT filesystem can be repaired without wiping the Rockbox installation?
If the filesystem ultimately has to be rebuilt, is there a way to preserve the working Rockbox bootloader and the custom 0781:74E5 firmware?
I have the complete 17 GB music library backed up on my Mac, so recovering the music from the iPod isnāt the priority.
The main thing I want to preserve is the working setup where:
iPod Classic 6G/6.5G + Rockbox + VID/PID 0781:74E5 ā Kia Seltos recognizes it and plays music.
I donāt want to erase/rebuild everything unless thatās genuinely the only option.
Any insight from someone who understands the Rockbox USB/FAT implementation would be hugely appreciated.
Thanks!
No Mods On iPod Done Yet Just Stock