Re: [PATCH rc3 02/30] target/avr: Introduce AVR CPU class object

[Philippe Mathieu-Daudé]

On 1/27/20 3:39 AM, Aleksandar Markovic wrote:
> > +static void avr_cpu_initfn(Object *obj)
> > +{
> > +    AVRCPU *cpu = AVR_CPU(obj);
> > +
> > +    cpu_set_cpustate_pointers(cpu);
> > +
> > +#ifndef CONFIG_USER_ONLY
> > +    /* Set the number of interrupts supported by the CPU. */
> > +    qdev_init_gpio_in(DEVICE(cpu), avr_cpu_set_int,
> > +            sizeof(cpu->env.intsrc) * 8);
> > +#endif
> > +}
>
> A question for Michael:
>
> What is CONFIG_USER_ONLY doing here, if we know AVR cores from this
> series doesn't have and will never have user mode, since they do not
> work with the kernel?
>
> Do you plan to support some AVR 32-bit CPUs in the same file, which
> would be able to have linux-user mode? But, in this case, many files
> must be completely redone. My advice is to separate them completely,
> and that this file supports only 8-bit AVR cores, and in that case
> checks for CONFIG_USER_ONLY do not make sense.

You are right, CONFIG_USER_ONLY doesn't make sense.

Suggestion: add in target/avr/cpu.h:

  #ifdef CONFIG_USER_ONLY
  #error "AVR 8-bit does not support user mode"
  #endif