[kata-dev] how much does kata depend on kernel features?

Dr. David Alan Gilbert dgilbert at redhat.com
Thu Apr 2 09:11:03 UTC 2020

* Ilya Dmitrichenko (errordeveloper at gmail.com) wrote:
> I'd like to use kata to test applications on different kernels,
> ideally I'd like to be able to import kernels from most modern
> distributions and test on those kernels without any changes.
> So far I've not been able to boot kata VMs successfully with
> Ubuntu 18,04 and CentOS 8 kernels.
> I have built a custom image and been able to boot that with
> the original kata kernel from 1.11.0-alpha1.
> My question is - should it be fundamentally possible to make
> kata work with any kernel, or all of its functionality as a k8s
> runtime is highly dependent on kernel it uses?

It should if it has the features needed.
You need a shared filesystem, so that's either 9p or virtiofs.
9p is turned off in CentOS/RHEL; virtiofs was added but only recently.
I think you should find it in the current (March 2020) CentOS Stream kernel.

I think Ubuntu 18.04 probably has 9p turned on, but I'm less sure.

There are some vsock features that make life easier on Kata as well;
I'm less clear as to exactly when those landed.


> When I look at qemu flags, I see a lot of things going on,
> that make me think there is a set of very specific features
> that kata depends on, is that correct? Or can one reduce
> this set of features to something more basic?
> Also, if I am to use firecracker, would my options be any
> different or worse actually?
> Ilya

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Dr. David Alan Gilbert / dgilbert at redhat.com / Manchester, UK

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