Re: [PATCH v2 13/15] uapi: hyperv: Add mshv driver headers hvhdk.h, hvhdk_mini.h, hvgdk.h, hvgdk_mini.h

[Nuno Das Neves]

On 8/19/2023 3:26 AM, Greg KH wrote:
> 
> My "strong" opinion is the one kernel development rule that we have,
> "you can not break userspace".  So, if you change these
> values/structures/whatever in the future, and userspace tools break,
> that's not ok and the changes have to be reverted.
> 
> If you can control both sides of the API here (with open tools that you
> can guarantee everyone will always update to), then yes, you can change
> the api in the future.
> 

This is true for us - we contribute and maintain support for this driver
in Cloud Hypervisor[1], an open source VMM.

We also do a check of the hypervisor version when the driver loads, and
refuse to proceed if it is running on an incompatible hypervisor.

Thanks,
Nuno Das Neves


[1] https://github.com/cloud-hypervisor/cloud-hypervisor