On Fri, Aug 09, 2024 at 12:11:36AM +0200, Miguel Ojeda wrote: > Now that `RUSTC_VERSION_TEXT` exists, use it to rebuild `core` when the > version text changes (which in turn will trigger a rebuild of all the > kernel Rust code). > > This also applies to proc macros (which only work with the `rustc` that > compiled them), via the already existing dependency on `core.o`. That > is cleaned up in the next commit. > > However, this does not cover host programs written in Rust, which is > the same case in the C side. > > This is accomplished by referencing directly the generated file, instead > of using the `fixdep` header trick, since we cannot change the Rust > standard library sources. This is not too much of a burden, since it > only needs to be done for `core`. > > Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx> > --- > Masahiro: I used `$(objtree)` here since we still use it in the rest of > this `Makefile`, but please let me know if you prefer otherwise. Thanks! > > rust/Makefile | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/rust/Makefile b/rust/Makefile > index 6c0644b6090c..966743a9ee25 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -370,7 +370,8 @@ $(obj)/core.o: private skip_clippy = 1 > $(obj)/core.o: private skip_flags = -Wunreachable_pub > $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym)) > $(obj)/core.o: private rustc_target_flags = $(core-cfgs) > -$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE > +$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs \ > + $(wildcard $(objtree)/include/config/RUSTC_VERSION_TEXT) FORCE > +$(call if_changed_dep,rustc_library) > ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),) > $(obj)/core.o: scripts/target.json > -- > 2.46.0 Looks good to me, but I'd prefer something like the suggestion from Masahiro: https://lore.kernel.org/linux-kbuild/CAK7LNAQBG0nDupXSgAAk-6nOqeqGVkr3H1RjYaqRJ1OxmLm6xA@xxxxxxxxxxxxxx/
