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

bbslhb — Wed, 01 Apr 2020 02:00:14 GMT

Thank you, Simon.

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

Simon — Tue, 31 Mar 2020 20:47:44 GMT

[quote user=""] So I don't know where the code started from[/quote]

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.

[quote user=""]and how the code run threads.[/quote]

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.

Hopefully, I've understood this correctly.

Best regards,

Simon