Re: [PATCH 12/15] hyperv: move VMBus connection ids to uapi

[Christoph Hellwig]

On Wed, Dec 21, 2016 at 09:29:39AM +0300, Roman Kagan wrote:
> QEMU in particular.  We're planning to implement VMBus devices in QEMU
> and would like to have the definitions shared with the Linux guest
> drivers for Hyper-V.

And that's everything but a userspace API.  The way to go for protocol
constants is to have a normal kernel header that is not exported, and
a copy of it wherever else you need it.