On 3/12/21 11:39 AM, Paolo Bonzini wrote:
> On 12/03/21 11:25, Claudio Fontana wrote:
>> We can register them from there if needed I think,, but where ever we
>> do it, we still have to point to the one set of ops or the other,
>> depending on the cpu model that is finally chosen.
>>
>> So when we attach the tcg cpu accelerator object to the cpu, we
>> currently should check which cpu it is, and behave accordingly.
>>
>> Maybe this is better? Ie, not set the tcg ops in different places (in
>> the v7m cpu class init and in the tcg cpu accel init),
>>
>> but rather set them just in a single place, when we attach the accel
>> cpu object, checking which cpu profile it is somehow (TBD), and then
>> behave accordingly?
>
> Take a look at
> https://wiki.qemu.org/User:Paolo_Bonzini/Machine_init_sequence#Basic_phases.
> The phases are:
>
> - creating backends (PHASE_NO_MACHINE)
>
> - creating machine (after which PHASE_MACHINE_CREATED is entered)
>
> - creating accelerator (after which PHASE_ACCEL_CREATED is entered)
>
> - initializing embedded devices (in machine_run_board_init, after which
> PHASE_MACHINE_INITIALIZED is entered), including CPUs
>
> - creating devices (in qmp_x_exit_preconfig, after which
> PHASE_MACHINE_READY is entered)
>
> And the last is where the guest actually starts.
>
> I think that you should have a callback in the accelerator that runs
> after -cpu is processed and before PHASE_MACHINE_INITIALIZED is entered.
> So the right place to add it would be machine_run_board_init.
>
> Maybe some kind of double dispatch, where the accelerator has an
> acc->init_cpu(acc, cc) method and the CPU has a cc->init_tcg_ops(cc)
> method. Then TCG's init_cpu calls into the latter.
>
> Paolo
>
>
Thanks, digesting this.
What you describe as:
acc->init_cpu(acc, cc)
seems to me we already have, as the accel class init, fe, for x86/tcg:
static void tcg_cpu_accel_class_init(ObjectClass *oc, void *data)
{
AccelCPUClass *acc = ACCEL_CPU_CLASS(oc);
#ifndef CONFIG_USER_ONLY
acc->cpu_realizefn = tcg_cpu_realizefn;
#endif /* CONFIG_USER_ONLY */
acc->cpu_class_init = tcg_cpu_class_init;
acc->cpu_instance_init = tcg_cpu_instance_init;
}
acc->cpu_class_init() call would then be the acc->init_cpu call you mention.
The only thing we seem to be missing is the cc->init_tcg_ops(cc)..
Ciao,
Claudio
