Mazda Connect Filesystem and Partition Layout
The Gen 6 Mazda Connect CMU runs Linux 3.0.35 from the Freescale i.MX6 BSP (L3.0.35_4.1.0, still documented on NXP’s i.MX6D product page). The kernel is built SMP PREEMPT (dual-core capable and preemptible) with no mandatory access control: no SELinux, no AppArmor.
The storage layout is the part that trips people up. The primary filesystem is not ext4, it’s Datalight Reliance Nitro on a FlashFX NAND flash translation layer. That single fact decides how you can and can’t pull data off one of these units.
Source basis: SPI-NOR, eMMC, and NAND sizes plus mount names are cross-checked against silverchris’s CMU hardware notes. Kernel config and partition details come from local rootfs analysis.
Storage devices
Section titled “Storage devices”Three physical storage components sit on the board:
| Device | Part | Size | Role |
|---|---|---|---|
| SPI-NOR | Macronix MX25L6445 | 8 MB | Bootloader, failsafe, config |
| NAND | Datalight FlashFX FTL | 1 GB | Root filesystem and user data |
| eMMC | Micron | 4 GB | Navigation data, TTS voices, speech grammars |
The SPI-NOR holds the bootloader and a failsafe image, the NAND holds the OS the system actually runs, and the eMMC holds the large read-only resource blobs the speech and navigation stacks need.
Filesystems
Section titled “Filesystems”| Type | Usage |
|---|---|
| Datalight Reliance (relfs) | Primary filesystem on NAND |
| squashfs | Manufacturing configuration |
| tmpfs | Temporary files, RAM-backed |
Partitions
Section titled “Partitions”| Partition | Size | Mode | Contents |
|---|---|---|---|
| Root filesystem | 602 MB | Read-only | Linux OS and JCI applications |
| User data | 316 MB | Read-write | User data, logs, persistent settings |
| Persistent config | varies | Read-write | Config that survives factory reset |
| tmpfs | varies | Read-write (RAM) | Runtime temp files, cleared on reboot |
| eMMC resources | 4 GB | Read-only | Navigation data, TTS voices, speech grammars |
The root partition is mounted read-only by default. The user data partition is the primary writable storage that persists across reboots.
Root filesystem
Section titled “Root filesystem”Holds the Linux OS, all JCI service binaries, the HTML/JS/CSS UI application, the Opera browser, and shared libraries. This is the partition a firmware update rewrites.
User data
Section titled “User data”Stores Bluetooth pairings, saved settings, logs, and persistent modifications. It survives firmware updates in some cases, but don’t treat it as a backup — assume an update can wipe it.
eMMC resources
Section titled “eMMC resources”The 4 GB eMMC carries navigation data, text-to-speech voice models, speech recognition grammars, and prompt audio. The speech engine depends on these resources; strip them and voice commands stop working.
Why a NAND dump won’t mount
Section titled “Why a NAND dump won’t mount”Because the root and user-data partitions live on Datalight Reliance Nitro over a FlashFX FTL, a raw NAND dump will not mount on a standard Linux box. Reliance is a proprietary transactional filesystem and the FTL sits between the raw flash pages and the filesystem image — mount -t ext4 or the usual loop-mount tricks see noise, not a directory tree. Reading the contents needs Datalight’s kernel module or a tool that understands the Reliance on-disk format. The 8 MB SPI-NOR and the eMMC are more conventional and easier to inspect.
Related pages
Section titled “Related pages”- Boot Chain — how these partitions get mounted during startup
- Runtime Analysis — live storage measurements and the running process landscape
- Services — the service architecture that lives on the root partition