On 11/27/20 7:21 AM, Paolo Bonzini wrote:
> On 26/11/20 23:32, Claudio Fontana wrote:
>> + if (acc) {
>> + object_class_foreach(accel_init_cpu_int_aux, cpu_type, false, acc);
>> + }
>
> Any reason to do it for cpu_type only, rather than for all subclasses of
> CPU_RESOLVING_TYPE? This would remove the cpu_type argument to
> accel_init_cpu_interfaces and accel_init_interfaces.
>
> Otherwise I haven't done a careful review yet but it looks very nice,
> thanks!
>
> Paolo
>
Hi Paolo,
going back to this topic:
while doing some experiments in applying the ACCEL_CPU_TYPE classes for all
targets (TCG for now, not KVM or other hw accels),
and merging all tcg cpu ops,
I did encounter some issue.
For the simplest of targets like hppa for example, it works just fine, we can
do:
static void hppa_tcg_cpu_class_init(CPUClass *cc)
{
cc->tcg_ops.initialize = hppa_translate_init;
cc->tcg_ops.do_interrupt = hppa_cpu_do_interrupt;
cc->tcg_ops.cpu_exec_interrupt = hppa_cpu_exec_interrupt;
cc->tcg_ops.synchronize_from_tb = hppa_cpu_synchronize_from_tb;
cc->tcg_ops.tlb_fill = hppa_cpu_tlb_fill;
#ifndef CONFIG_USER_ONLY
cc->tcg_ops.do_unaligned_access = hppa_cpu_do_unaligned_access;
#endif
}
*(later on I will try to change the cc->tcg_ops thing to something that ends up
in cc->accel_cpu->tcg_ops->initialize, as I try to merge tcg_ops with
accel_cpu, but this is spoiler of the future)*
static void hppa_tcg_cpu_accel_class_init(ObjectClass *oc, void *data)
{
AccelCPUClass *acc = ACCEL_CPU_CLASS(oc);
acc->cpu_class_init = hppa_tcg_cpu_class_init;
}
static const TypeInfo hppa_tcg_cpu_accel_type = {
.name = ACCEL_CPU_NAME("tcg"),
.parent = TYPE_ACCEL_CPU,
.class_init = hppa_tcg_cpu_accel_class_init,
};
static void hppa_cpu_register_types(void)
{
type_register_static(&hppa_cpu_type_info);
type_register_static(&hppa_tcg_cpu_accel_type);
}
type_init(hppa_cpu_register_types)
So this is good.
But with things like cris/ for example,
the tcg functions to use are actually versioned per each subclass of
TYPE_CRIS_CPU.
Different tcg_ops need to be used for different subclasses of the
CPU_RESOLVING_TYPE.
So in order to avoid code in the class initialization like this:
if (version1) { then set the tcg ops for version 1; }
if (version2) { then set the tcg ops for version 2; ...} etc,
we could define the right tcg op variants corresponding to the cpu variants, so
that everything can be matched automatically.
But I think we'd need to pass explicitly the cpu type in
accel_init_cpu_interfaces for this to work..
we could still in the future call accel_init_cpu_interfaces multiple times,
once for each cpu model we want to use.
Or, we could do something else: we could delay the accel cpu interface
initialization and call it in cpu_create(const char *typename),
where typename needs to be known for sure.
This last option seems kinda attractive, but any ideas?
Thanks, ciao,
Claudio
