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

From: Andrew Lunn <andrew@lunn.ch>
To: FUJITA Tomonori <fujita.tomonori@gmail.com>
Cc: gregkh@linuxfoundation.org, netdev@vger.kernel.org,
	rust-for-linux@vger.kernel.org, miguel.ojeda.sandonis@gmail.com
Subject: Re: [PATCH v2 3/3] net: phy: add Rust Asix PHY driver
Date: Sat, 7 Oct 2023 02:20:25 +0200	[thread overview]
Message-ID: <bafa74fb-0b5b-4215-b702-8dd6799fef55@lunn.ch> (raw)
In-Reply-To: <20231007.085400.1040380280563980814.fujita.tomonori@gmail.com>

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