Re: [Qemu-devel] virtio-gpu doesn't build if you do a linux-headers update from kvm/next

[Paolo Bonzini]

On 05/11/2015 18:05, Laszlo Ersek wrote:
>> > Surely the kernel uapi includes is that textual format. Once stuff is
>> > accepted into the master kernel tree there is your stable API.
> What is uapi for? If it is for QEMU (the userspace process) to consume
> the host kernel's services, then I agree.

uapi = Userspace API.

> If uapi is for the guest kernel to consume (= drive) QEMU's virtual
> hardware, then I strongly disagree. In that case Linux is just one of
> the possible guests that can drive that hardware.

Kernel-only headers can and will include uapi headers, though not the
other way round.  So there can be indeed a case where a typo in uapi
headers causes both QEMU and the guest kernel to deviate from the spec.

> (Side point: and QEMU is just one of the emulators / hypervisors that
> can provide that hardware. Which is why the actual hardware description
> should exist independently of both.)

Typically it exists as an industry standard (e.g. the virtio
specification) or a datasheet.

Paolo

> I'll elaborate elsewhere in the thread.