Re: [kvm-unit-tests PATCH v6 07/10] s390x: css: msch, enable test

Janosch Frank
2020-05-15T08:53:22Z

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On 5/15/20 10:25 AM, Cornelia Huck wrote:
> On Fri, 15 May 2020 09:11:52 +0200
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> On 2020-05-14 14:08, Cornelia Huck wrote:
>>> On Tue, 28 Apr 2020 10:27:36 +0200
>>> Pierre Morel <pmorel@linux.ibm.com> wrote:
>>>
>>>> On 2020-04-27 15:11, Janosch Frank wrote:
>>>>> On 4/24/20 12:45 PM, Pierre Morel wrote:
>>>
>>>>>> This is NOT a routine to really enable the channel, no retry is done,
>>>>>> in case of error, a report is made.
>>>>>
>>>>> Would we expect needing retries for the pong device?
>>>>
>>>> Yes it can be that we need to retry some instructions if we want them to
>>>> succeed.
>>>> This is the case for example if we develop a driver for an operating system.
>>>> When working with firmware, sometime, things do not work at the first
>>>> time. Mostly due to races in silicium, firmware or hypervisor or between
>>>> them all.
>>>>
>>>> Since our purpose is to detect such problems we do not retry
>>>> instructions but report the error.
>>>>
>>>> If we detect such problem we may in the future enhance the tests.
>>>
>>> I think I've seen retries needed on z/VM in the past; do you know if
>>> that still happens?
>>>
>>
>> I did not try the tests under z/VM, nor direct on an LPAR, only under
>> QEMU/KVM.
>> Under QEMU/KVM, I did not encounter any need for retry, 100% of the
>> enabled succeeded on first try.
>
> Yep, QEMU/KVM should be fine. Do you plan to run this on anything else?
>

I'd like to have it compatible with z/VM / LPAR as well if it isn't too
much work. You never know when you need it and having tests for all
hypervisors has been quite a help in the past.

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