Re: [PATCH] ppc/spapr: fix default cpu for pre-10.0 machines.

[Harsh Prateek Bora <harshpb@linux.ibm.com>]

On 3/13/25 15:02, Daniel P. Berrangé wrote:
> On Wed, Mar 12, 2025 at 11:28:04AM +0530, Harsh Prateek Bora wrote:
>> When POWER10 CPU was made as default, we missed keeping POWER9 as
>> default for older pseries releases (pre-10.0) at that time.
>> This caused breakge in default cpu evaluation for older pseries
>> machines and hence this fix.
>>
>> Fixes: 51113013f3 ("ppc/spapr: change pseries machine default to POWER10 CPU")
>> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
>> ---
>>   hw/ppc/spapr.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index c15340a58d..b31a91e2e2 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -4748,6 +4748,7 @@ static void spapr_machine_9_2_class_options(MachineClass *mc)
>>   {
>>       spapr_machine_10_0_class_options(mc);
>>       compat_props_add(mc->compat_props, hw_compat_9_2, hw_compat_9_2_len);
>> +    mc->default_cpu_type = POWERPC_CPU_TYPE_NAME("power9_v2.2");
>>   }
> 
> This doesn't make sense.
> 
> AFAICT, the commit 51113013f3 was introduced in the QEMU 9.0.0 release,
> so it is correct that every machine from pseries-9.0 and newer had the
> POWER10 CPU model.
> 
> What broke were the machines that already existed prior to the
> 9.0.0 release, whose default CPU got changed.  IOW, the pseries-8.2
> and earlier machines.

Thanks Daniel for catching this.
I should have checked using git tags. I have posted v2 here:

https://lore.kernel.org/qemu-devel/20250313094705.2361997-1-harshpb@linux.ibm.com/T/#u

regards,
Harsh

> 
> 
> With regards,
> Daniel