| Message ID | 20250210-rust-path-remap-v1-1-021c48188df1@weissschuh.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | kbuild, rust: use -fremap-path-prefix to make paths relative | expand |
On Tue, Feb 11, 2025 at 2:11 AM Thomas Weißschuh <linux@weissschuh.net> wrote: > > Remap source path prefixes in all output, including compiler > diagnostics, debug information, macro expansions, etc. > This removes a few absolute paths from the binary and also makes it > possible to use core::panic::Location properly. > > Equivalent to the same configuration done for C sources in > commit 1d3730f0012f ("kbuild: support -fmacro-prefix-map for external modules") > and commit a73619a845d5 ("kbuild: use -fmacro-prefix-map to make __FILE__ a relative path"). > > Link: https://doc.rust-lang.org/rustc/command-line-arguments.html#--remap-path-prefix-remap-source-names-in-output > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> I will apply this if Miguel gives Ack. > --- > Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/Makefile b/Makefile > index 9e0d63d9d94b90672f91929e5e148e5a0c346cb6..ac35083180c825b72f13149ec3acfd7d6d74ef98 100644 > --- a/Makefile > +++ b/Makefile > @@ -1068,6 +1068,7 @@ endif > # change __FILE__ to the relative path to the source directory > ifdef building_out_of_srctree > KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=) > +KBUILD_RUSTFLAGS += $(call rustc-option,--remap-path-prefix=$(srcroot)/=) > endif > > # include additional Makefiles when needed > > --- > base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d > change-id: 20250210-rust-path-remap-e97cec71e61a > > Best regards, > -- > Thomas Weißschuh <linux@weissschuh.net> >
On Mon, Feb 10, 2025 at 6:11 PM Thomas Weißschuh <linux@weissschuh.net> wrote: > > Remap source path prefixes in all output, including compiler > diagnostics, debug information, macro expansions, etc. Hmm... We don't do all the cases in the C side -- the docs ask to use `KCFLAGS` when one wants to remove them in the debug info: https://docs.kernel.org/kbuild/reproducible-builds.html#absolute-filenames I am not sure if there is a reason not to cover all cases in C (Cc'ing Ben). If there is a reason to not do it for the debug info by default (or if we want to make it consistent with C even if there is no reason), then I think we would need `-Zremap-path-scope=...` too, which is still unstable, sadly (Cc'ing Urgau who implemented it for Rust 1.75.0): https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/remap-path-scope.html https://github.com/rust-lang/rust/issues/111540 In such case, we would also need probably to mention in the `reproducible-builds` docs how to achieve the same as in C (e.g. passing an extra `-Zremap-path-scope=debug`, since it aggregates with the previous ones, according to compiler flag docs). > # change __FILE__ to the relative path to the source directory Perhaps we could add a note to this comment with what we do in the Rust side. > +KBUILD_RUSTFLAGS += $(call rustc-option,--remap-path-prefix=$(srcroot)/=) I don't think we need `rustc-option`, since the flag is available since a long time ago (Rust 1.26.0). So we should be able to just do: KBUILD_RUSTFLAGS += --remap-path-prefix=$(srcroot)/= Cheers, Miguel
On Sat, Feb 15, 2025 at 1:57 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > I will apply this if Miguel gives Ack. Thanks Masahiro -- I left some comments above. This does remove some absolute paths for me, though not all (e.g. `core.o` that comes from the sysroot). Since it is an improvement already, if you want to apply it: Acked-by: Miguel Ojeda <ojeda@kernel.org> I leave below a diff that works for `core.o` for me -- it would do it in all cases, not just `building_out_of_srctree`, since it is outside the repository in all cases, which I think makes sense, e.g. in an in-tree build I get: $ strings rust/core.o | grep validations.rs lib/rustlib/src/rust/library/core/src/str/validations.rs Cheers, Miguel diff --git a/rust/Makefile b/rust/Makefile index ea3849eb78f6..42f242472031 100644 --- a/rust/Makefile +++ b/rust/Makefile @@ -438,7 +438,7 @@ $(obj)/exports.o: private skip_gendwarfksyms = 1 $(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: private rustc_target_flags = $(core-cfgs) --remap-path-prefix=$(rustc_sysroot)/= $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs \ $(wildcard $(objtree)/include/config/RUSTC_VERSION_TEXT) FORCE +$(call if_changed_rule,rustc_library)
diff --git a/Makefile b/Makefile index 9e0d63d9d94b90672f91929e5e148e5a0c346cb6..ac35083180c825b72f13149ec3acfd7d6d74ef98 100644 --- a/Makefile +++ b/Makefile @@ -1068,6 +1068,7 @@ endif # change __FILE__ to the relative path to the source directory ifdef building_out_of_srctree KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=) +KBUILD_RUSTFLAGS += $(call rustc-option,--remap-path-prefix=$(srcroot)/=) endif # include additional Makefiles when needed
Remap source path prefixes in all output, including compiler diagnostics, debug information, macro expansions, etc. This removes a few absolute paths from the binary and also makes it possible to use core::panic::Location properly. Equivalent to the same configuration done for C sources in commit 1d3730f0012f ("kbuild: support -fmacro-prefix-map for external modules") and commit a73619a845d5 ("kbuild: use -fmacro-prefix-map to make __FILE__ a relative path"). Link: https://doc.rust-lang.org/rustc/command-line-arguments.html#--remap-path-prefix-remap-source-names-in-output Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- Makefile | 1 + 1 file changed, 1 insertion(+) --- base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d change-id: 20250210-rust-path-remap-e97cec71e61a Best regards,