Why there is no main() in zephyr thread sample codes?

[bbslhb]

Hello:

    I am studying thread samples in nRF9160.

   There are two thread samples: "zephyr\samples\basic\threads" and “zephyr\samples\synchronization”.

    But I can't find main() in those two samples.

    So I don't know where the code started from and how the code run threads.

    Can you explain to me what is the entry point of the sample code?

    I know the code begin with 0x000000 in ram but I don't know which code is in 0x00000 and how the code run from 0x0000 to threads in those examples.

[Simon]

    So I don't know where the code started from

In a Zephyr/NCS example  z_cstart()→switch_to_main_thread() will run initially, which will invoke bg_thread_main()  that will look for a main() (Which will run in the Main System Thread). If main() is not defined, there is no problem (unless CONFIG_MULTITHREADING is set to n):

"If main() is not defined, or if it executes and then does a normal return, the main thread terminates normally and no error is raised."

If no main() is defined, this default weak main() function will be used.

and how the code run threads.

If you read Threads→Spawning a Thread, you can see that a thread can be spawn in two different ways; at run time or at compile time. In the sample zephyr/samples/basic/threads the latter method is used (compile-time). Check it out here.

The threads will then be ready and can be executed by the scheduler.

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Hopefully, I've understood this correctly.

Best regards,

Simon