On Sun, Nov 19, 2023 at 06:25:44PM +0900, FUJITA Tomonori wrote:

On Fri, 17 Nov 2023 23:01:58 +0000
Benno Lossin [off-list ref] wrote:

quoted

On 11/17/23 23:54, Andrew Lunn wrote:

quoted

Each kernel module should be in its own symbol name space. The only
symbols which are visible outside of the module are those exported
using EXPORT_SYMBOL_GPL() or EXPORT_SYMBOL(). A PHY driver does not
export anything, in general.

Being built in also does not change this.

Neither drivers/net/phy/ax88796b_rust.o nor
rust/doctests_kernel_generated.o should have exported this symbol.

I've no idea how this actually works, i guess there are multiple
passes through the linker? Maybe once to resolve symbols across object
files within a module. Normal global symbols are then made local,
leaving only those exported with EXPORT_SYMBOL_GPL() or
EXPORT_SYMBOL()? A second pass through linker then links all the
exported symbols thorough the kernel?

I brought this issue up in [1], but I was a bit confused by your last
reply there, as I have no idea how the `EXPORT_SYMBOL` macros work.

IIRC on the Rust side all public items are automatically GPL exported.

Hmm, they are public but doesn't look like exported by EXPORT_SYMBOL()
or EXPORT_SYMBOL_GPL().

Do they need to be public? Generally, a PHY driver does not export
anything. So you can probably make them private. We just however need
to ensure the compiler/linker does not think they are unused, so
throws them away.

I would however like to get an understanding how EXPORT_SYMBOL* is
supposed to work in rust. Can it really be hidden away? Or should
methods be explicitly marked like C code? What is the Rust equivalent
of the three levels of symbol scope we have in C?

	Andrew