Re: [PATCH RFC v2] vfio: Documentation for the migration region

Jason Gunthorpe
2021-12-02T17:42:07Z

On Thu, Dec 02, 2021 at 06:05:36PM +0100, Cornelia Huck wrote:
> On Wed, Dec 01 2021, Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> > On Wed, Dec 01, 2021 at 01:03:14PM -0700, Alex Williamson wrote:
> >> But if this document is suggesting the mlx5/QEMU interpretation is the
> >> only valid interpretations for driver authors, those clarifications
> >> should be pushed back into the uAPI header.
> >
> > Can we go the other way and move more of the uAPI header text here?
>
> Where should a userspace author look when they try to implement support
> for vfio migration? I think we need to answer that question first.
>
> Maybe we should separate "these are the rules that an implementation
> must obey" from "here's a more verbose description of how things work,
> and how you can arrive at a working implementation". The former would go
> into the header, while the latter can go into this document. (The
> generated documentation can be linked from the header file.)

I think the usual kernel expectation now is to find userspace
information either in man pages or in the Documentation/ html pages?

The uapi header is fine to be a terse summary of what the ioctl does
and some important points, but I wouldn't try to write a spec for
anything complicated in a header file.

Maybe Jonathan has an advice?

Thanks,
Jason