Re: [PATCH V2 1/4] libgpiod: Generate rust FFI bindings

[Viresh Kumar <viresh.kumar@xxxxxxxxxx>]

Hi Gerard,

On 17-12-21, 11:29, Gerard Ryan wrote:
> Hello,
> 
> I submitted https://lore.kernel.org/all/CAKycSdDMxfto6oTqt06TbJxXY=S7p_gtEXWDQv8mz0d9zt3Gvw@xxxxxxxxxxxxxx/
> and my attention was drawn here and have a few comments.
> 
> Firstly, I was wondering why you didn't create a separate *-sys crate
> for these bindings?
> see https://doc.rust-lang.org/cargo/reference/build-scripts.html#-sys-packages
> for more information.

I wasn't aware of it :(

I think yes this should be modified to a sys-crate, followed by wrapper crate to
contain the wrappers around it.

> Secondly, I noticed when developing my aforementioned, patch that
> `bindgen` adds quite a few dependencies that probably aren't needed by
> the average consumer of this crate.
> So I was wondering what are your thoughts about generating and
> committing a bindings.rs then optionally using these dependencies via
> a feature flag?

I don't have a strong preference either way, whatever works best.

Miguel, any suggestions ?

> Lastly, With your `make` integration, it looks like we could also
> remove the `cc` dependency by allowing `make` to build libgpiod
> instead and just linking with that, instead of compiling libgpiod
> twice.

I agree, that would be better. It wasn't integrated with Make earlier and so I
had to do it separately. But I may have some problem with it:

This is the vhost-device (gpio virtio) crate where I am using these bindings and
have the libgpiod as a dependency:

https://github.com/vireshk/vhost-device/blob/gpio/irq/src/gpio/Cargo.toml#L18

When I do a cargo build there (for vhost-device crate), it will try to build the
dependencies as well, i.e. libgpiod, and I need to build the libgpiod's C files
as well there. There are good chances that I need to build from source and
libgpiod isn't installed there. How do I do it with Make ?

-- 
viresh