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

FUJITA Tomonori
2023-10-06T23:54:04Z

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;

A long-term solution is under discussion.