| Message ID | 20240808221138.873750-6-ojeda@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kbuild: rust: add `RUSTC_VERSION` and reconfig/rebuild support | expand |
On Fri, Aug 9, 2024 at 7:12 AM Miguel Ojeda <ojeda@kernel.org> wrote: > > With the `RUSTC_VERSION_TEXT` rebuild support in place, now proc macros > can depend on that instead of `core.o`. > > This means that both the `core` and `macros` crates can be built in > parallel, and that touching `core.o` does not trigger a rebuild of the > proc macros. > > Signed-off-by: Miguel Ojeda <ojeda@kernel.org> > --- > rust/Makefile | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/rust/Makefile b/rust/Makefile > index 966743a9ee25..40c8d2c57024 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -329,9 +329,8 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@ > --crate-name $(patsubst lib%.so,%,$(notdir $@)) $< > > # Procedural macros can only be used with the `rustc` that compiled it. > -# Therefore, to get `libmacros.so` automatically recompiled when the compiler > -# version changes, we add `core.o` as a dependency (even if it is not needed). > -$(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE > +$(obj)/libmacros.so: $(src)/macros/lib.rs \ > + $(wildcard $(objtree)/include/config/RUSTC_VERSION_TEXT) FORCE > +$(call if_changed_dep,rustc_procmacro) The touched file, include/config/*, is an implementation detail in Kconfig and fixdep. Rather, I'd like to put the string "CONFIG_RUST_VERSION_TEXT" in the comment of the source file. This is the idea adopted in include/linux/compiler-version.h diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 5be0cb9db3ee..91be2112ceee 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -2,6 +2,10 @@ //! Crate for all kernel procedural macros. +// When fixdep scans this, it will find this string "CONFIG_RUSTC_VERSION_TEXT" +// and add dependency on include/config/RUSTC_VERSION_TEXT, which is touched +// by Kconfig when the version string from the compiler changes. + #[macro_use] mod quote; mod concat_idents; I do not know how to do it for rust/core.o because there is no in-tree source file. But, can we add rust/core.rs, from which rustlib/src/rust/library/core/src/macros/mod.rs is imported? > > quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@ > -- > 2.46.0 > >
On Fri, Aug 9, 2024 at 7:31 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > The touched file, include/config/*, is an implementation detail > in Kconfig and fixdep. > > Rather, I'd like to put the string "CONFIG_RUST_VERSION_TEXT" > in the comment of the source file. > > This is the idea adopted in include/linux/compiler-version.h +1, I did it this way to follow the same pattern to the previous patch on `core.o`, since that one needed another approach, but I am happy to change it. > I do not know how to do it for rust/core.o because there is no in-tree > source file. > > But, can we add rust/core.rs, from which > rustlib/src/rust/library/core/src/macros/mod.rs is imported? That is an interesting idea... :) Hmm... I think `core` is a bit too special for that, since we need attributes on the crate root and it is the one defining things like `include!`. Even if we generated the file on the fly to mimic the original, we would still need to handle the paths for each module or recreate a directory hierarchy or similar. We are also in talks with the Rust project to figure out building `core` in a stable way, so the details around it may change too, e.g. probably something like passing a flag like `-Cbuild-std=core`. They may also want to figure out the right input file path themselves, i.e. rather than having to provide one from our side. So I think a hack may not be worth it compared to depending on the implementation detail, and may be a bit brittle until we know the final details of that. Thanks! Cheers, Miguel
diff --git a/rust/Makefile b/rust/Makefile index 966743a9ee25..40c8d2c57024 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -329,9 +329,8 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@ --crate-name $(patsubst lib%.so,%,$(notdir $@)) $< # Procedural macros can only be used with the `rustc` that compiled it. -# Therefore, to get `libmacros.so` automatically recompiled when the compiler -# version changes, we add `core.o` as a dependency (even if it is not needed). -$(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE +$(obj)/libmacros.so: $(src)/macros/lib.rs \ + $(wildcard $(objtree)/include/config/RUSTC_VERSION_TEXT) FORCE +$(call if_changed_dep,rustc_procmacro) quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
With the `RUSTC_VERSION_TEXT` rebuild support in place, now proc macros can depend on that instead of `core.o`. This means that both the `core` and `macros` crates can be built in parallel, and that touching `core.o` does not trigger a rebuild of the proc macros. Signed-off-by: Miguel Ojeda <ojeda@kernel.org> --- rust/Makefile | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)