Re: [PATCH v3 0/2] KVM: ARM: Enable vtimers with user space gic

Alexander Graf
2016-09-16T19:36:42Z

> Am 16.09.2016 um 15:46 schrieb Andrew Jones <drjones@redhat.com>:
>
>> On Fri, Sep 16, 2016 at 03:30:27PM +0200, Christoffer Dall wrote:
>>> On Fri, Sep 16, 2016 at 02:31:42PM +0200, Paolo Bonzini wrote:
>>>
>>>
>>> On 16/09/2016 14:30, Christoffer Dall wrote:
>>>>>>> This patch set allows user space to receive vtimer events as well as mask
>>>>>>> them, so that we can handle all vtimer related interrupt injection from user
>>>>>>> space, enabling us to use architected timer with user space gic emulation.
>>>>>>
>>>>>> I have already voiced my concerns in the past, including face to face,
>>>>>> and I'm going to repeat it: I not keen at all on adding a new userspace
>>>>>> interface that is going to bitrot extremely quickly.
>>>>>
>>>>> You don't have automated tests set up? It's not going to bitrot if you
>>>>> test it, either with kvm-unit-tests or just by smoke-testing Linux.
>>>>> It's _for_ the raspi, but it's not limited to it.
>>>>
>>>> Our automated testing situation is not great, no. Something we're
>>>> looking at, but have resource problems with.
>>>
>>> But it's not a good reason to hold back a feature...
>>
>> I didn't say that exactly, but choosing not to merge something we cannot
>> maintain and which we're not paid to look after and where there's a
>> minimal interest, is not entirely unreasonable.
>>
>> That being said, I'm not categorically against these patches, but I
>> share Marc's view that we've already seen that non-vgic support had been
>> broken for multiple versions without anyone complaining, and without
>> automated testing or substantial interest in the work, the patches
>> really are likely to bit-rot.
>>
>> But I haven't even looked at the patches in detail, I was just replying
>> to the comment about testing.
>
> This may be a great time to start encouraging feature writers to submit
> kvm-unit-tests patches at the same time as the feature (Hi Alex :-)

I actually started off implementing this with the help of kvm-unit-tests. It's awesome!

I'm lacking actual irq support to make the test reasonable though and wanted to get the kernel bits out first :). But I'll sit down on that again soon I hope.

Alex