Re: [PATCH ppc-next v2 42/52] target-ppc: Convert CPU definitions

["Andreas Färber" <afaerber@suse.de>]

Am 22.02.2013 15:23, schrieb Alexander Graf:
> 
> On 18.02.2013, at 10:16, Andreas Färber wrote:
> 
>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
>> index 2c64c63..e601059 100644
>> --- a/target-ppc/kvm.c
>> +++ b/target-ppc/kvm.c
>> @@ -1263,7 +1263,7 @@ static void kvmppc_host_cpu_initfn(Object *obj)
>>
>>     assert(kvm_enabled());
>>
>> -    if (pcc->info->pvr != mfpvr()) {
>> +    if (pcc->pvr != mfpvr()) {
>>         fprintf(stderr, "Your host CPU is unsupported.\n"
>>                 "Please choose a supported model instead, see -cpu ?.\n");
>>         exit(1);
>> @@ -1275,30 +1275,38 @@ static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data)
>>     PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(oc);
>>     uint32_t host_pvr = mfpvr();
>>     PowerPCCPUClass *pvr_pcc;
>> -    ppc_def_t *spec;
>>     uint32_t vmx = kvmppc_get_vmx();
>>     uint32_t dfp = kvmppc_get_dfp();
>>
>> -    spec = g_malloc0(sizeof(*spec));
>> -
>>     pvr_pcc = ppc_cpu_class_by_pvr(host_pvr);
>>     if (pvr_pcc != NULL) {
>> -        memcpy(spec, pvr_pcc->info, sizeof(*spec));
>> +        pcc->pvr          = pvr_pcc->pvr;
>> +        pcc->svr          = pvr_pcc->svr;
>> +        pcc->insns_flags  = pvr_pcc->insns_flags;
>> +        pcc->insns_flags2 = pvr_pcc->insns_flags2;
>> +        pcc->msr_mask     = pvr_pcc->msr_mask;
>> +        pcc->mmu_model    = pvr_pcc->mmu_model;
>> +        pcc->excp_model   = pvr_pcc->excp_model;
>> +        pcc->bus_model    = pvr_pcc->bus_model;
>> +        pcc->flags        = pvr_pcc->flags;
>> +        pcc->bfd_mach     = pvr_pcc->bfd_mach;
>> +#ifdef TARGET_PPC64
>> +        pcc->sps          = pvr_pcc->sps;
>> +#endif
>> +        pcc->init_proc    = pvr_pcc->init_proc;
>> +        pcc->check_pow    = pvr_pcc->check_pow;
> 
> It would be nice to have field copying more streamlined. This way, whoever adds a new field to the class needs to know that he also has to change this piece of code, which is non-obvious.
> 
> Speaking of which, why aren't you copying parent_reset for example?

parent_reset is already assigned by the .parent's class_init before this
class_init is executed.

> Or asked differently: Why can't we do a memcpy? We're really trying to do a subclass of the parent class here, no?

I did suggest making it a subclass in the cover letter, as follow-up. :)

The issue is we need to know which parent class. And we do not have any
guarantee that in ..._register_types() the types corresponding to our
PVR have already been registered.

Therefore we would need to move host CPU type registration to
kvm_arch_init(), as suggested by Eduardo for x86. A side effect would be
that the type is not yet registered at -cpu ? time. If that is
acceptable to you (we might hard-code its output within CONFIG_KVM), I
can send you a patch.

Andreas

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