Re: [libgpiod][PATCH 6/6] core: add the kernel uapi header to the repository

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Mon, Jan 25, 2021 at 6:55 AM Kent Gibson <warthog618@xxxxxxxxx> wrote:
>

[snip!]

> >
> > I don't like the ifdef hell so I prefer to bundle the header. I'm open
> > to other suggestions, although I can't come up with anything else.
> >
>
> Going off on a bit of a tangent, but I'm trying to add support for
> decoding the GPIO ioctls into strace and am running up against a similar
> issue.
>
> The way strace does it is to check the uAPI header on the host and use
> it if possible.  To handle where it may be stale, local types are
> defined that mirror any types that may have been added since the header
> was originally released.  If the corresponding type is available in the
> linux header then it is used, else the local type.
>
> This obviously creates a lot of pointless boilerplate code and
> preprocessor chicanery so I floated the idea of just including the latest
> header in the strace tree, as you are doing here for libgpiod.
> But that raised the issue of licencing, specifically if you copy the
> linux/gpio.h into a source tree does that mean that the whole project
> becomes GPL 2.0?  That is an issue for strace as it is LGPL 2.1 - as is
> libgpiod.
>
> The Linux uAPI headers are under the GPL-2.0 WITH Linux-syscall-note,
> which is also not totally clear on this point[1].
>
> My gut feeling was that using and even copying API headers doesn't
> constitute a derived work, as per the FSF view quoted in [1], and
> ethically might even be less of a violation than copying and re-defining
> individual types, but I'd rather not rely on a gut feeling.
>
> Is there some clear opinion or precedent on this point?
> i.e. are libgpiod and strace in legal licence jeopardy if they include
> gpio.h in their source tree?
>
> Cheers,
> Kent.
>
> [1] https://lkml.org/lkml/2020/2/21/2193

Thanks for pointing that out. I lack the legal knowledge to have an
opinion of my own on this.

Cc'ing Greg KH for help.

Greg: do you know if it's fine to bundle a 'GPL-2.0 WITH
Linux-syscall-note' uAPI header together with an LGPL-v2.1-or-later
user-space shared library?

Best Regards,
Bartosz Golaszewski