Ethernet emac_main.c stack to small (IDFGH-608)

[ardiehl]

i'm currently on idf 3.1.1 but this problem exists with all previous versions as well. I have a lan8720 connected to the esp32. When the lan board is connected everything works fine. When the lan8720 board is not connected and i try to initialize ethernet, a stack overflow will happen in emacT. Increasing the stacksize in components/ethernet/emac_main.c from 2048 to 3072 solves the problem.

The problem does not happen with the ethernet sample. Within my code, this happens at various places. I have added a ps command to find the free stack of each runnig task. After changing the emac stacksize to 3k i get a free stack space of 600 bytes for the emac task. So there is more needed than the 2k currently in emac_main.c:

evse> ps
task name       cpu  prio  min stack free   run time count
------------------------------------------------------------------
main              0     1           11120           468527   0.03%
IDLE              1     0             528        703788899  46.72%
IDLE              0     0             456        746745074  49.57%
....
emacT           any    20             600          4497798   0.30%

when the board is connected, the needed stacksize is much lower, this is the ps output with 3k emacT stack and a connected lan8720 board

evse> ps
task name       cpu  prio  min stack free   run time count
------------------------------------------------------------------
main              0     1           10928           326231   0.40%
...
emacT           any    20            2328            14452   0.02%

So, in case the board is not connected, the needed stacksize grew by 1728 bytes. Could this be related to the ESP_LOG* routines called to output errors ? (i have set "Default log verbosity" = Warning)

this is the fix in emac_main.c (esp_eth_init_internal)

xTaskCreate(emac_task, "emacT", 3072, NULL, EMAC_TASK_PRIORITY, &emac_task_hdl);

• Development Kit: ESP32-DevKitC or my own board with ESP32-WROOM-32 + Waveshare LAN8720
• Module or chip used: ESP32-WROOM-32
• IDF version 3.1.1 or any previous version
• Build System: Make
• Compiler version 5.2.0
• Operating System: Linux
• Power Supply: USB or external 5V

sdkconfig.zip

[suda-morris]

@ardiehl Thanks for your analysis. I will look into it later.
BTW, since IDF v3.2, the stack size has been configurable.