example_gpio_intr not working on verilator

[JuanSapriza]

In #363 we added a second interrupt in the example_gpio_intr application to test that the array of handlers inside the gpio hal was working. At that time, that was working.

Note that both interrupts are exactly the same but with different handlers.

Symptoms

• Run make run-app-verilator PROJECT=example_gpio_intr
• Open the terminal to see the output (e.g. screen /dev/pts/x, replacing x for the screen reported in the terminal)
• The output should be

Write 1 to GPIO 30 and wait for interrupt...
handler 1
Write 1 to GPIO 30 and wait for interrupt...  

• The triggering of the second interrupt is not seen. We expect to see

handler 2
Success

at the end, but this never happens.

Things I have tried

• Changing the uint8_t gpio_intr_flag to volatile. → No change (but this change should be kept)
• Shortening the PRINTFs at the beginning of each sequence →The second PRINTF is not printed.
• Not triggering the second interrupt, but instead changing the flag → The program finishes successfully.

    while(gpio_intr_flag == 0) {
        CSR_CLEAR_BITS(CSR_REG_MSTATUS, 0x8);
        gpio_intr_flag = 1;  // <---------------
        CSR_SET_BITS(CSR_REG_MSTATUS, 0x8);
    }