Link problem after upgrade to esp-idf v5.x

niels · May 3, 2023, 2:43pm

Normally I tend to be able to handle link errors such as ‘undefined reference’, but in this case, after updating to esp-idf release 5.0.1 I hit a wall with one of the mbedtls libraries.
A newly build mbedtls library is in the project path, but apparently the linker doesn’t find the function names in the object file(s).
Any one has a clue?

Linking .pio\build\nodemcu-32s\firmware.elf
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\nodemcu-32s\src\AESdecrypt.o:(.literal.KamDecrypt+0x18): undefined reference to `mbedtls_gcm_init'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\nodemcu-32s\src\AESdecrypt.o:(.literal.KamDecrypt+0x1c): undefined reference to `mbedtls_gcm_setkey'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\nodemcu-32s\src\AESdecrypt.o:(.literal.KamDecrypt+0x20): undefined reference to `mbedtls_gcm_auth_decrypt'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\nodemcu-32s\src\AESdecrypt.o:(.literal.KamDecrypt+0x24): undefined reference to `mbedtls_gcm_free'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: .pio\build\nodemcu-32s\src\AESdecrypt.o: in function `KamDecrypt':
C:\Users\niels\Documents\PlatformIO\Projects\PowerMeter/src/AESdecrypt.c:69: undefined reference to `mbedtls_gcm_init'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: C:\Users\niels\Documents\PlatformIO\Projects\PowerMeter/src/AESdecrypt.c:74: undefined reference to `mbedtls_gcm_setkey'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: C:\Users\niels\Documents\PlatformIO\Projects\PowerMeter/src/AESdecrypt.c:76: undefined reference to `mbedtls_gcm_auth_decrypt'
c:/users/niels/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/11.2.0/../../../../xtensa-esp32-elf/bin/ld.exe: C:\Users\niels\Documents\PlatformIO\Projects\PowerMeter/src/AESdecrypt.c:82: undefined reference to `mbedtls_gcm_free'
collect2.exe: error: ld returned 1 exit status
*** [.pio\build\nodemcu-32s\firmware.elf] Error 1

maxgerhardt · May 3, 2023, 4:39pm

Check out whether it’s the same as

github.com/platformio/platform-espressif32

Cannot use mbedtls in esp-idf from main firmware

opened 12:32PM - 09 Nov 22 UTC

maxgerhardt

bug ESP-IDF

Reproduction: 1. Create a new blank ESP-IDF project for ESP32 Dev Module 2. Mo…dify the source code `src/main.c` to ```cpp #include "mbedtls/aes.h" void app_main() { mbedtls_aes_context ctx; mbedtls_aes_init(&ctx); } ``` 3, Hit compile: ``` Linking .pio/build/esp32dev/firmware.elf /home/max/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld: .pio/build/esp32dev/src/main.o:(.literal.app_main+0x0): undefined reference to `mbedtls_aes_init' /home/max/.platformio/packages/toolchain-xtensa-esp32/bin/../lib/gcc/xtensa-esp32-elf/8.4.0/../../../../xtensa-esp32-elf/bin/ld: .pio/build/esp32dev/src/main.o: in function `app_main': /home/max/temp/espidf_mbedtls_bug/src/main.c:6: undefined reference to `mbedtls_aes_init' collect2: error: ld returned 1 exit status *** [.pio/build/esp32dev/firmware.elf] Error 1 ``` 4. Realize when looking at the verbose compile log, that when the mbedtls library is compiled, it does so with the flag ``` -DMBEDTLS_CONFIG_FILE=\"mbedtls/esp_config.h\" ``` 5. Realize that this flag is not in the compiler invocation for the firmware files in `src/`. 6. Set source code to ```cpp #define MBEDTLS_CONFIG_FILE "mbedtls/esp_config.h" #include "mbedtls/aes.h" void app_main() { mbedtls_aes_context ctx; mbedtls_aes_init(&ctx); } ``` --> it compiles thanks to the [config file being correctly selected](https://github.com/espressif/mbedtls/blob/89da85968417ce4a163b7275cb22f159995c271d/include/mbedtls/aes.h#L43-L48) ``` Linking .pio/build/esp32dev/firmware.elf Retrieving maximum program size .pio/build/esp32dev/firmware.elf Checking size .pio/build/esp32dev/firmware.elf Advanced Memory Usage is available via "PlatformIO Home > Project Inspect" RAM: [ ] 3.5% (used 11312 bytes from 327680 bytes) Flash: [== ] 16.1% (used 169253 bytes from 1048576 bytes) Building .pio/build/esp32dev/firmware.bin esptool.py v4.2.1 Creating esp32 image... Merged 2 ELF sections Successfully created esp32 image. ============[SUCCESS] Took 7.62 seconds ============= ``` Conclusion: "Something" is preventing the `src/` files in the main PlatformIO projects from getting the critical macro for the mbedtls config file. This causes problems when calling some mbedtls functions which the actual config redefined [to have other names](https://github.com/espressif/esp-idf/blob/1cb31e50943bb757966ca91ed7f4852692a5b0ed/components/mbedtls/port/include/aes_alt.h#L30-L39). See discussion in [community topic](https://community.platformio.org/t/linking-problem-with-the-blufi-example/30365/6?u=maxgerhardt).

niels · May 3, 2023, 5:57pm

Thanks @maxgerhardt, once again you hit it right on. That was exactly the problem, linking is now working thanks to the workaround(s).