On Fri, Sep 16, 2016 at 09:36:42PM +0200, Alexander Graf wrote:

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Am 16.09.2016 um 15:46 schrieb Andrew Jones [off-list ref]:

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On Fri, Sep 16, 2016 at 03:30:27PM +0200, Christoffer Dall wrote:

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On Fri, Sep 16, 2016 at 02:31:42PM +0200, Paolo Bonzini wrote:


On 16/09/2016 14:30, Christoffer Dall wrote:

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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.

I'm glad it looks like a good base for you. I need to get this series
https://github.com/rhdrjones/kvm-unit-tests/commits/arm/gic refreshed and
merged, and also it's time to start looking into adding interrupt
injection to chr-testdev. With those in place I hope it'll be an even
better base for you.

Thanks,
drew