Re: [RFC v5 11/12] i386: centralize initialization of cpu accel interfaces

[Claudio Fontana]

On 11/24/20 10:31 PM, Eduardo Habkost wrote:
> On Tue, Nov 24, 2020 at 09:13:13PM +0100, Paolo Bonzini wrote:
>> On 24/11/20 17:22, Claudio Fontana wrote:
>>> +static void x86_cpu_accel_init(void)
>>>  {
>>> -    X86CPUAccelClass *acc;
>>> +    const char *ac_name;
>>> +    ObjectClass *ac;
>>> +    char *xac_name;
>>> +    ObjectClass *xac;
>>> -    acc = X86_CPU_ACCEL_CLASS(object_class_by_name(accel_name));
>>> -    g_assert(acc != NULL);
>>> +    ac = object_get_class(OBJECT(current_accel()));
>>> +    g_assert(ac != NULL);
>>> +    ac_name = object_class_get_name(ac);
>>> +    g_assert(ac_name != NULL);
>>> -    object_class_foreach(x86_cpu_accel_init_aux, TYPE_X86_CPU, false, 
>>> &acc);
>>> +    xac_name = g_strdup_printf("%s-%s", ac_name, TYPE_X86_CPU);
>>> +    xac = object_class_by_name(xac_name);
>>> +    g_free(xac_name);
>>> +
>>> +    if (xac) {
>>> +        object_class_foreach(x86_cpu_accel_init_aux, TYPE_X86_CPU, false, 
>>> xac);
>>> +    }
>>>  }
>>> +
>>> +accel_cpu_init(x86_cpu_accel_init);
>>
>> If this and cpus_accel_ops_init are the only call to accel_cpu_init, I'd
>> rather make them functions in CPUClass (which you find and call via
>> CPU_RESOLVING_TYPE) and AccelClass respectively.
> 
> Making x86_cpu_accel_init() be a CPUClass method sounds like a
> good idea.  This way we won't need a arch_cpu_accel_init() stub
> for non-x86.
> 
> accel.c can't use cpu.h, correct?  We can add a:
> 
>   CPUClass *arch_base_cpu_type(void)
>   {
>       return object_class_by_name(CPU_RESOLVING_TYPE);
>   }
> 
> function to arch_init.c, to allow target-independent code call
> target-specific code.
> 

Hi Eduardo,

we can't use arch-init because it is softmmu only, but we could put this in 
$(top_srcdir)/cpu.c

however, it would be very useful to put a:

#define TYPE_ACCEL_CPU "accel-" CPU_RESOLVING_TYPE
#define ACCEL_CPU_NAME(name) (name "-" TYPE_ACCEL_CPU)

in an H file somewhere, for convenience for the programmer that has to 
implement subclasses in target/xxx/

But it is tough to find a header where CPU_RESOLVING_TYPE can be used.

We could I guess just use plain "cpu" instead of CPU_RESOLVING_TYPE,
maybe that would be acceptable too? The interface ends up in CPUClass, so maybe 
ok?

So we'd end up having

accel-cpu

instead of the previous

accel-x86_64-cpu

on top of the hierarchy.

Ciao,

Claudio