Re: [Qemu-devel] [PATCH 2/4] mips_malta: Change default KVM cpu to 24Kc (no FP)

[Paolo Bonzini <pbonzini@redhat.com>]

Il 27/06/2014 10:43, Aurelien Jarno ha scritto:
> On Thu, Jun 26, 2014 at 10:44:23AM +0100, James Hogan wrote:
>> Change the default Malta CPU model for when KVM is enabled to 24Kc which
>> doesn't have floating point support compared to the 24Kf.
>>
>> The resulting incorrect Config CP0 register value doesn't get passed to
>> KVM yet as KVM doesn't expose it, however we should ensure it is set
>> correctly now to reduce the risk of breaking migration/loadvm to a
>> future version of QEMU/Linux that does support them.
>>
>> Signed-off-by: James Hogan <james.hogan@imgtec.com>
>> Cc: Aurelien Jarno <aurelien@aurel32.net>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  hw/mips/mips_malta.c | 7 ++++++-
>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/mips/mips_malta.c b/hw/mips/mips_malta.c
>> index 2868ee5b0307..c0841991f4e9 100644
>> --- a/hw/mips/mips_malta.c
>> +++ b/hw/mips/mips_malta.c
>> @@ -949,7 +949,12 @@ void mips_malta_init(MachineState *machine)
>>  #ifdef TARGET_MIPS64
>>          cpu_model = "20Kc";
>>  #else
>> -        cpu_model = "24Kf";
>> +        if (kvm_enabled()) {
>> +            /* Don't enable FPU on KVM yet */
>> +            cpu_model = "24Kc";
>> +        } else {
>> +            cpu_model = "24Kf";
>> +        }
>>  #endif
>>      }
>
> Given the explanations in the other mails, that looks fine to me, that
> said I think we should at least warn the user that we are disabling some
> features, instead of doing it silently. This is what is done for example
> on x86 when a CPU feature is not available.

I agree.  James, can you send v2 of this patch only?

Paolo