On 07/24/2018 12:59 PM, Daniel P. Berrangé wrote:
> On Tue, Jul 24, 2018 at 06:53:54PM +0200, Cornelia Huck wrote:
>> On Tue, 24 Jul 2018 18:08:21 +0200
>> Jiri Denemark <jdenemar@xxxxxxxxxx> wrote:
>>
>>> On Mon, Jul 23, 2018 at 17:45:33 -0400, Collin Walling wrote:
>>>> Use model name "qemu" instead of "max" when calling
>>>> query-cpu-model-expansion for s390 on tcg.
>>>>
>>>> Signed-off-by: Collin Walling <walling@xxxxxxxxxxxxx>
>>>> ---
>>>> src/qemu/qemu_capabilities.c | 5 ++++-
>>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
>>>> index 23b4833..e9b44cc 100644
>>>> --- a/src/qemu/qemu_capabilities.c
>>>> +++ b/src/qemu/qemu_capabilities.c
>>>> @@ -2356,7 +2356,10 @@ virQEMUCapsProbeQMPHostCPU(virQEMUCapsPtr qemuCaps,
>>>>
>>>> if (tcg || !virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM)) {
>>>> virtType = VIR_DOMAIN_VIRT_QEMU;
>>>> - model = "max";
>>>> + if (ARCH_IS_S390(qemuCaps->arch))
>>>> + model = "qemu";
>>>> + else
>>>> + model = "max";
>>>
>>> I think we should also check if "max" is a supported model
>>> (qemuCaps->tcgCPUModels is already populated at this point) and only use
>>> "qemu" on s390 if "max" is not supported. And please, report the issue
>>> to QEMU developers since one of the reasons behind "max" is its
>>> universal availability on everywhere CPU model expansion is supported.
>>
>> Hm, can you point me to that discussion? A quick search through the
>> QEMU log gives me the addition of the "max" model on i386 as a
>> replacement to the "host" model for !kvm, but nothing about it being
>> universal...
>
> I don't recall the link but "max" is supposed to be the standard shorthand
> for "enable all the features supported by the virt type". IOW, 'max' should
> work both KVM and TCG ("host" was only well defined for KVM), and across
> all architectures.
>
> So having to use a different name on s390 is a bug in QEMU imho.
>
> Regards,
> Daniel
>
Thanks for expanding on what the "max" model name is suppose to be. I wonder if a
s/"qemu"/"max" in QEMU would suffice (I'm taking a shot in the dark here.)
@Connie, @David, you both are far more knowledgeable in this area than I am. What
do either of you suggest for moving forward with this? Should we forward this
discussion on qemu-devel?
--
Respectfully,
- Collin Walling
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