Re: [libgpiod,v1.6.x,0/3] build: fix compile issues against non-glibc

[Bartosz Golaszewski <brgl@xxxxxxxx>]

On Mon, Feb 27, 2023 at 9:56 PM Benjamin Li <benl@xxxxxxxxxxxx> wrote:
>
> On 2/25/23 6:10 AM, Bartosz Golaszewski wrote:
> > I applied patch 2/3 as it's a fix. For the rest of them - my goal for
> > the v1.6.x series is to not support it anymore, than is absolutely
> > necessary - that means no new features and android build looks like
> > one to me. Any chance you can carry this locally?
>
> Sure, we don't mind. But I'd like to gently remind that a lot of device
> manufacturers like us have platforms that are unfortunately stuck on
> older kernel versions that don't have the v2 IOCTLs.
>

Ah, right. Android again. :)

Does the android build file need to live in the top source directory?
Can it go into a separate contrib/ directory where this kind of less
maintained stuff could go?

> Are there plans to introduce backwards compatibility to libgpiod v2
> to support pre-5.10 kernels without v2 IOCTLs? I assume no based on
> your talk from July since there's a major data model re-architecture.
>

Not really, as the previous uAPI is quite limited and a lot of
features of libgpiod v2 would no longer work.

> Anyways, as an aside it would be nice to note in the README about the
> 5.10-or-later requirement for libgpiod v2 (apologies if it's mentioned
> and I missed it).

Sounds good I will add it. Unfortunately it's impossible to know the
kernel version at build-time so configure checks are useless. We also
carry our own copy of the kernel uAPI headers for other reasons so
checking the target's headers won't fly either.

Bart

>
> I didn't learn about the compatibility gap until I tested libgpiod v2
> tools on-device and found that they failed without a sufficiently new
> kernel. Bummer as I was looking forward to being able to reference
> GPIOs by just the labels in the CLI!
>
> >
> > For v2.x I'm open to adding it but have a couple comments, see the
> > relevant email threads.
>
> Thanks, will respond there.
>
> Ben
>
> >
> > Bart