Finally I could make it work, but only after commenting out the printf() calls in the funtions main() and hello_M4() in M4 project. (see code snippet at bottom)
Otherwise the while(1) statement is never reached.
I have no idea what could be the reason for this behaviour.
Unfortunately I can even not check the terminal output of printf(). I tried to use the terminal of DS-5 with following settings, but get no output, neither from M4 nor A5

(even though changing the UART_PORT to UART2 according to Rev G Tower Board Changes)
// dual_core_m4.c
...
int main()
{
/* Enable IO for LED operation */
ENABLE_LEDS;
// printf("Hello World from M4 Core!\n"); // NEEDS TO BE COMMENTED OUT
while(1)
{
/* Blink Tower LEDs */
led_blink_tower(1);
/* Say Hello */
hello_M4();
}
return 0;
}
...
void hello_M4()
{
/* Lock gate to write UART, then unlock */
SEMA4->GATE[1] = CORE1_LOCK;
if(SEMA4->GATE[1] == CORE1_LOCK)
{
/* Output message from M4 */
// printf("Hello M4!\n"); // NEEDS TO BE COMMENTED OUT
/* Unlock Semaphore */
SEMA4->GATE[1] = UNLOCK;
}
}