wasm-micro-runtime/product-mini/platforms/zephyr/simple-file/README.md

File sample

This sample demonstrates the use of WASI API to interact with the file system.

🛠️ Work in progress: The sample is functional but be aware that just a small part of WASI File System API was tested. Actual Zephyr APIs:

• directory creation = fs_mkdir
• file opening/creation = fs_open
• file write = fs_write
• file offset = fs_seek
• file read = fs_read
• file close = fs_close
• directory close = fs_closedir

Run Command

• Zephyr Build

  1. Build: Replace nucleo_h743zi with your board name and the WAMR_BUILD_TARGET in CMakeList.txt with your target architecture.

     ZEPHYR_BASE=~/zephyrproject/zephyr \
     WAMR_ROOT_DIR=~/wasm-micro-runtime \
     WASI_SDK_PATH=~/wasi-sdk-21.0 \
     WAMR_APP_FRAMEWORK_DIR=~/wamr-app-framework \
     west build . -b nucleo_h563zi -p always 
     

     ⚠️ Warning: The flags ZEPHYR_BASE, WAMR_ROOT_DIR, WASI_SDK_PATH, and WAMR_APP_FRAMEWORK_DIR need to be set otherwise the build will fail.

  2. Flash:

     ZEPHYR_BASE=~/zephyrproject/zephyr west flash
     

  3. Monitor: Use a serial link to monitor the output. Personally, I use minicom.

     minicom -D /dev/ttyACM0
     

  4. Debug: Curently investigating.

• WebAssembly Module

  ❗ Important: I used wasi-sdk 21 to compile the module. I still haven't tried the module with the new wasi-sdk 22.

  1. Compile: in the wasm-apps folder.

     ~/wasi-sdk-21.0/bin/clang --sysroot=/home/user/wasi-sdk-21.0/share/wasi-sysroot -nodefaultlibs -lc -o file.wasm file.c -z stack-size=8192 -Wl,--initial-memory=65536 -Wl,--export=__heap_base -Wl,--export=__data_end
     

  2. generate a C header: Use xxd or other tool, I also put simple python script. At application root simple-file/.

     python3 to_c_header.py
     

     Be free to modify the script to fit your needs.

Output

The output should be similar to the following:

*** Booting Zephyr OS build v3.6.0-4305-g2ec8f442a505 ***
Area 3 at 0x1f0000 on flash-controller@40022000 for 65536 bytes
[00:00:00.067,000] <inf> littlefs: LittleFS version 2.8, disk version 2.1
[00:00:00.074,000] <inf> littlefs: FS at flash-controller@40022000:0x1f0000 is 8 0x2000-byte blocks with 512 cycle
[00:00:00.085,000] <inf> littlefs: sizes: rd 16 ; pr 16 ; ca 64 ; la 32
[00:00:00.092,000] <err> littlefs: WEST_TOPDIR/modules/fs/littlefs/lfs.c:1351: Corrupted dir pair at {0x0, 0x1}
[00:00:00.103,000] <wrn> littlefs: can't mount (LFS -84); formatting
[00:00:00.114,000] <inf> littlefs: /lfs mounted
/lfs mount: 0
[00:00:00.120,000] <inf> main: stdin = 0
[00:00:00.124,000] <inf> main: stdout = 1
[00:00:00.128,000] <inf> main: stderr = 2
[00:00:00.133,000] <inf> main: global heap size: 131072
[00:00:00.142,000] <inf> main: Wasm file size: 34682
[00:00:00:000 - 2000AFE0]: WASI context initialization: START

[OS] os_rwlock_init
[OS] os_rwlock_init
[00:00:00:000 - 2000AFE0]: WASI context initialization: END

[00:00:00.190,000] <inf> main: main found
Hello WebAssembly Module !

mkdir returned 0
fopen Succeed
fwrite returned 13
fseek returned 0
fread returned 13
buffer read = Hello, World!

[00:00:00.225,000] <inf> main: main executed
[00:00:00.230,000] <inf> main: wasi exit code: 0
[00:00:00.239,000] <inf> main: elapsed: 178ms
[00:00:03.158,000] <inf> phy_mii: PHY (0) Link speed 100 Mb, full duplex

[00:00:00.051,000] <inf> phy_mii: PHY (0) ID 7C131