OpenSTLinux directory structure

Applicable for

STM32MP13x lines, STM32MP15x lines, Unknown MPU, Unknown MPU, Unknown MPU

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This article aims at presenting, as example, the directory structure of the Linux root file system available on STM32 board.

All files and directories are located under the root directory (/), in compliance with the File system Hierarchy Standard.

This root directory corresponds to the Linux root file system (rootfs partition), as defined in Flash partitions. Note also that the user file system (userfs partition), the boot file system (bootfs partition) and the vendor file system (vendorfs partition) can be accessed through the /usr/local mounting point, through the /boot mounting point, and through the /vendor mounting point respectively.

Information

In practice, this article uses the release STM32MP15-Ecosystem-unknown for the STM32MPU Embedded Software distribution as an example to illustrate the Linux directory structure. If you are using a different release, the names of the directories and files might differ.

The directories are shown in green, while the files are in black.

/                            Root directory (rootfs partition)
├── bin                      Essential user binaries (e.g. /bin/cat, /bin/ls, /bin/cp...)
│   └── [...]
├── boot                     Mounting point for the boot file system (bootfs partition): see below
├── dev                      Device files (e.g. /dev/null, /dev/tty0, /dev/video0...)
├── etc                      System-wide configuration files (e.g. /etc/xdg/weston/weston.ini Weston configuration file...)
├── home                     Users' home directories (containing saved files, personal settings...)
├── lib                      Essential system libraries for the binaries in /bin and /sbin (e.g. libncurses.so.*...)
│   ├── modules
│   │   └── 6.6.78          The directory name is the linux version (i.e. 6.6.78)
│   │       ├── kernel       Linux kernel modules
│   │       │   └── [...]
│   │       ├── modules.dep  List of module dependencies (generated by depmod)
│   │       └── [...]
│   └── [...]
├── lost+found
├── media                    Mount points for removable media devices
├── mnt                      Temporarily mounted file systems
├── proc                     Pseudo filesystem providing process and kernel information as files (e.g. /proc/cpuinfo, /proc/version...)
├── root                     Home directory for the root user)
├── run                      Run-time variable data (information about the running system since last boot)
├── sbin                     Essential system binaries (e.g. /sbin/fsck, /sbin/init, /sbin/modprobe...)
├── sys                      Information about devices, drivers, and some kernel features (e.g. /sys/kernel/debug akadebgufs...)
├── tmp                      Temporary files
├── usr                      User utilities and applications
│   ├── bin                  Non-essential user binaries (e.g. /usr/bin/lsusb, /usr/bin/weston...)
│   ├── lib                  Non-essential system libraries for the binaries in /usr/bin and /usr/sbin
│   ├── local                Mounting point for the user file system (userfs partition): see below
│   ├── sbin                 Non-essential system binaries (e.g. /usr/sbin/alsactl, /usr/sbin/weston.sh...)
│   ├── share                Architecture-independent (shared) data
│   └── [...]
├── var                      Variable files
└── vendor                   Mounting point for the vendor file system (vendorfs partition): see below

• Boot file system mounting point

/boot    bootfs partition
├── stm32<soc>-dk[*].dtb    Linux kernel device tree blob files for discovery board(s)
├── stm32<soc>-ev[*].dtb    Linux kernel device tree blob files for evaluation board(s)
├── [...]
├── uImage                  Linux kernel binary image file (with U-Boot wrapper)
└── [...]

• User file system mounting point

/usr/local    userfs partition
├── Cube-[M4|M33]-examples    Examples for M4 (STM32CubeMP1) Package or M33 (STM32CubeMP2) running on Arm® Cortex®M
│   ├── STM32MP<soc>-DK       Examples of firmwares running on Arm Cortex-M4 or Cortex-M33 
│   │   ├── Applications
│   │   │   ├── <Applications Name>
│   │   |   |    ├── <Application Name>                      OpenAMP TTY echo application
│   │   │   |    |    ├── <script name>.sh                   Script to start/stop this application
│   │   │   |    |    ├── lib
│   │   │   |    |    │   └── firmware
│   │   │   |    |    │       └── <Application Name>.elf     Firmware for this application
│   │   │   |    |    └── README                             Helper file for this application
│   │   │   │    └── [...]                                   Others applications with the same structure (script, helper file and firmware)
│   │   │   └── [...]                                        Others applications with the same structure (script, helper file and firmware)
│   │   ├── Demonstrations
│   │   │   ├── AI_Character_Recognition                     Artificial intelligence character recognition demonstration
│   │   │        └── lib
│   │   │            └── firmware
│   │   │                └── AI_Character_Recognition.elf    Firmware for this demonstration
.   .   .
.   .   .
.   .   .

├── Linux-A7-examples    Examples for Linux® running on Arm® Cortex®-A7
│   ├── GPIO             GPIO examples
│   │   ├── buttons
│   │   │   ├── button_gpio_exti.sh    Script for this example
│   │   |   └── README.md              Helper file for this example
│   │   └── leds                       Same structure for this example relative to the leds
│   │       └── [...]
│   └── [...]                          Same structure for all the examples
├── demo                               All files needed (e.g. Python scripts, pictures, media files...) for the GTK demo launcher
│   └── [...]
├── lost+found
└── weston-start-at-startup
    └── start_up_demo_launcher.sh      Script to start the GTK demo launcher

• Vendor file system mounting point

/vendor    vendorfs partition
├── [*].so    Specific vendor libraries (e.g. Vivante libraries OpenGL ES, OpenVG and EGL)
└── [...]

Microprocessor unit

Linux^® is a registered trademark of Linus Torvalds.

also known as

Das U-Boot -- the universal boot loader (see U-Boot)

Arm^® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

Cortex^®

Open asymmetric multi-processing (See https://www.openampproject.org/)

TeleTYpewriter

Artificial intelligence

General-purpose input/output (A realization of open ended transmission between devices on an embedded level. These pins available on a processor can be programmed to be used to either accept input or provide output to external devices depending on user desires and applications requirements.)

Open graphics library (see http://www.opengl.org/ for more details)

Open vector graphics (see http://www.khronos.org/openvg/ for more details)

Khronos native platform graphics interface (See http://www.khronos.org/egl/ for more details)