> From: Alessandro Pistocchi <apukbusin...@gmail.com>
> Date: Thu, 29 Apr 2021 00:50:32 +0200
> Content-Type: text/plain; charset="UTF-8"
>
> Hi all,
> in the kernel I see the code below (file: arm64/dev/ampint.c lines:643-666).
>
> void
> ampintc_irq_handler(void *frame)
> {
> struct ampintc_softc *sc = ampintc;
> struct intrhand *ih;
> void *arg;
> uint32_t iack_val;
> int irq, pri, s, handled;
>
> iack_val = ampintc_iack();
> #ifdef DEBUG_INTC
> if (iack_val != 27)
> printf("irq %d fired\n", iack_val);
> else {
> static int cnt = 0;
> if ((cnt++ % 100) == 0) {
> printf("irq %d fired * _100\n", iack_val);
> #ifdef DDB
> db_enter();
> #endif
> }
>
> }
> #endif
>
> Does anyone know what interrupt 27 is for? It seems to fire quite often.
It probably was the serial console on the machine that was used to
develop this driver. At least that is what I've used that snippet of
code for in the past. It is not a good idea to print stuff in the
interrupt handler for the device that is used for console output since
you end up triggering more interrupts that way. But I've always
changed the number to whatever was appropriate for the machine at
hand. In other word, 27 is just a number.
