Re: [PATCH v2 3/3] net: phy: add Rust Asix PHY driver

Andrew Lunn
2023-10-07T00:20:32Z

On Sat, Oct 07, 2023 at 08:54:00AM +0900, FUJITA Tomonori wrote:
> On Fri, 6 Oct 2023 18:55:23 +0200
> Andrew Lunn <andrew@lunn.ch> wrote:
>
> >> How about adding CONFIG_RUST_PHYLIB to the first patch. Not
> >> selectable, it's just a flag for Rust PHYLIB support.
> >
> > We have to be careful with names. To some extent, CONFIG_PHYLIB means
> > the core of phylib. So it could be that CONFIG_RUST_PHYLIB means the
> > core of phylib written in rust? I doubt that will ever happen, but we
> > are setting a naming scheme here which i expect others will blindly
> > cut/paste. What we actually want is a symbol which represents the Rust
> > binding onto the phylib core. So i think it should have BINDING, or
> > WRAPPER or something like that in the name.
>
> Good point. Let's save CONFIG_PHYLIB for someday.
>
>
> >> diff --git a/init/Kconfig b/init/Kconfig
> >> index 4b4e3df1658d..2b6627aeb98c 100644
> >> --- a/init/Kconfig
> >> +++ b/init/Kconfig
> >> @@ -1889,7 +1889,7 @@ config RUST
> >> depends on !GCC_PLUGINS
> >> depends on !RANDSTRUCT
> >> depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> >> depends on PHYLIB=y
> >> + select RUST_PHYLIB
> >
> > I know the rust build system is rather limited at the moment, but is
> > this required? Is it possible to build the rust code without the
> > phylib binding? Can your `RUST_PHYLIB` add phylib.rs to a Makefile
> > target only if it is enabled?
>
> A short-term solution could work, I think.
>
> config RUST
> bool "Rust support"
> depends on HAVE_RUST
> depends on RUST_IS_AVAILABLE
> depends on !MODVERSIONS
> depends on !GCC_PLUGINS
> depends on !RANDSTRUCT
> depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
> select CONSTRUCTORS
> help
> Enables Rust support in the kernel.
>
> This allows other Rust-related options, like drivers written in Rust,
> to be selected.
>
> It is also required to be able to load external kernel modules
> written in Rust.
>
> See Documentation/rust/ for more information.
>
> If unsure, say N.
>
> config RUST_PHYLIB_BINDING
> bool "PHYLIB bindings support"
> depends on RUST
> depends on PHYLIB=y
> help
> Adds support needed for PHY drivers written in Rust. It provides
> a wrapper around the C phlib core.
>
>
> Then we can conditionally build build the PHYLIB bindings.
>
> diff --git a/rust/kernel/net.rs b/rust/kernel/net.rs
> index fbb6d9683012..33fc1531a6c0 100644
> --- a/rust/kernel/net.rs
> +++ b/rust/kernel/net.rs
> @@ -2,4 +2,5 @@
>
> //! Networking.
>
> +#[cfg(CONFIG_RUST_BINDINGS_PHYLIB)]
> pub mod phy;

This looks reasonable. If you spin a new version with all these
Kconfig changes, i will do some compile testing.

Andrew