OS2 test MBED_A21 (Call function before main) failed only with IAR

[jeromecoutant]

Bug

On master branch, test MBED_A21 is FAIL for all STM32 targets only with IAR:

MBED_A21 Call function before main (mbed_main) NUCLEO_F091RC IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_F103RB IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_F207ZG IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_F303ZE IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_F446RE IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_F767ZI IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_L073RZ IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_L152RE IAR FAIL
MBED_A21 Call function before main (mbed_main) NUCLEO_L476RG IAR FAIL

Target
STM32

Toolchain:
IAR

[jeromecoutant]

Proposition:

diff --git a/platform/mbed_sdk_boot.c b/platform/mbed_sdk_boot.c

@@ -109,6 +109,10 @@ 
int __low_level_init(void)
   return 1;
 }

+void __iar_argc_argv() {
+    mbed_main();
+}
+
 #endif

[0xc0170]

Thanks for reporting ! Either we can do what you proposed, but I believe better place for IAR would be in their cmain file, where we already call other init functions.

https://github.com/ARMmbed/mbed-os/blob/master/cmsis/TOOLCHAIN_IAR/cmain.S#L88 (right after argc) we can invoke mbed_main.

          FUNCALL __cmain, mbed_main()
        BL      mbed_main()

[0xc0170]

I'll send a patch rightaway now, will request a review

[0xc0170]

Done, pull request sent, please review.