kbuild: mark rustc (and others) invocations as recursive
`rustc` (like Cargo) may take advantage of the jobserver at any time (e.g. for backend parallelism, or eventually frontend too). In the kernel, we call `rustc` with `-Ccodegen-units=1` (and `-Zthreads` is 1 so far), so we do not expect parallelism. However, in the upcoming Rust 1.76.0, a warning is emitted by `rustc` [1] when it cannot connect to the jobserver it was passed (in many cases, but not all: compiling and `--print sysroot` do, but `--version` does not). And given GNU Make always passes the jobserver in the environment variable (even when a line is deemed non-recursive), `rustc` will end up complaining about it (in particular in Make 4.3 where there is only the simple pipe jobserver style). One solution is to remove the jobserver from `MAKEFLAGS`. However, we can mark the lines with calls to `rustc` (and Cargo) as recursive, which looks simpler. This is being documented as a recommendation in `rustc` [2] and allows us to be ready for the time we may use parallelism inside `rustc` (potentially now, if a user passes `-Zthreads`). Thus do so. Similarly, do the same for `rustdoc` and `cargo` calls. Finally, there is one case that the solution does not cover, which is the `$(shell ...)` call we have. Thus, for that one, set an empty `MAKEFLAGS` environment variable. Link: https://github.com/rust-lang/rust/issues/120515 [1] Acked-by: Masahiro Yamada <masahiroy@kernel.org> Link: https://github.com/rust-lang/rust/pull/121564 [2] Link: https://lore.kernel.org/r/20240217002638.57373-1-ojeda@kernel.org [ Reworded to add link to PR documenting the recommendation. ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda
parent
e944171070
commit
ecab4115c4
4
Makefile
4
Makefile
@ -1197,7 +1197,7 @@ prepare0: archprepare
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# All the preparing..
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prepare: prepare0
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ifdef CONFIG_RUST
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$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
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+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
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$(Q)$(MAKE) $(build)=rust
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endif
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@ -1707,7 +1707,7 @@ $(DOC_TARGETS):
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# "Is Rust available?" target
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PHONY += rustavailable
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rustavailable:
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$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
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+$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
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# Documentation target
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#
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@ -40,7 +40,7 @@ obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.o
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ifdef CONFIG_RUST
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# `$(rust_flags)` is passed in case the user added `--sysroot`.
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rustc_sysroot := $(shell $(RUSTC) $(rust_flags) --print sysroot)
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rustc_sysroot := $(shell MAKEFLAGS= $(RUSTC) $(rust_flags) --print sysroot)
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rustc_host_target := $(shell $(RUSTC) --version --verbose | grep -F 'host: ' | cut -d' ' -f2)
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RUST_LIB_SRC ?= $(rustc_sysroot)/lib/rustlib/src/rust/library
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@ -108,14 +108,14 @@ rustdoc-macros: private rustdoc_host = yes
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rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
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--extern proc_macro
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rustdoc-macros: $(src)/macros/lib.rs FORCE
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$(call if_changed,rustdoc)
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+$(call if_changed,rustdoc)
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rustdoc-core: private rustc_target_flags = $(core-cfgs)
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rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
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$(call if_changed,rustdoc)
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+$(call if_changed,rustdoc)
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rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
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$(call if_changed,rustdoc)
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+$(call if_changed,rustdoc)
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# We need to allow `rustdoc::broken_intra_doc_links` because some
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# `no_global_oom_handling` functions refer to non-`no_global_oom_handling`
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@ -124,7 +124,7 @@ rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
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rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \
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-Arustdoc::broken_intra_doc_links
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rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
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$(call if_changed,rustdoc)
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+$(call if_changed,rustdoc)
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rustdoc-kernel: private rustc_target_flags = --extern alloc \
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--extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
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@ -132,7 +132,7 @@ rustdoc-kernel: private rustc_target_flags = --extern alloc \
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rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
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rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
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$(obj)/bindings.o FORCE
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$(call if_changed,rustdoc)
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+$(call if_changed,rustdoc)
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quiet_cmd_rustc_test_library = RUSTC TL $<
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cmd_rustc_test_library = \
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@ -146,18 +146,18 @@ quiet_cmd_rustc_test_library = RUSTC TL $<
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--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<
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rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE
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$(call if_changed,rustc_test_library)
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+$(call if_changed,rustc_test_library)
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rusttestlib-macros: private rustc_target_flags = --extern proc_macro
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rusttestlib-macros: private rustc_test_library_proc = yes
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rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
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$(call if_changed,rustc_test_library)
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+$(call if_changed,rustc_test_library)
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rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE
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$(call if_changed,rustc_test_library)
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+$(call if_changed,rustc_test_library)
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rusttestlib-uapi: $(src)/uapi/lib.rs rusttest-prepare FORCE
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$(call if_changed,rustc_test_library)
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+$(call if_changed,rustc_test_library)
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quiet_cmd_rustdoc_test = RUSTDOC T $<
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cmd_rustdoc_test = \
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@ -189,7 +189,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
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$(src)/kernel/lib.rs $(obj)/kernel.o \
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$(objtree)/scripts/rustdoc_test_builder \
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$(objtree)/scripts/rustdoc_test_gen FORCE
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$(call if_changed,rustdoc_test_kernel)
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+$(call if_changed,rustdoc_test_kernel)
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# We cannot use `-Zpanic-abort-tests` because some tests are dynamic,
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# so for the moment we skip `-Cpanic=abort`.
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@ -254,21 +254,21 @@ quiet_cmd_rustsysroot = RUSTSYSROOT
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$(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib
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rusttest-prepare: FORCE
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$(call if_changed,rustsysroot)
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+$(call if_changed,rustsysroot)
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rusttest-macros: private rustc_target_flags = --extern proc_macro
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rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
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rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
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$(call if_changed,rustc_test)
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$(call if_changed,rustdoc_test)
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+$(call if_changed,rustc_test)
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+$(call if_changed,rustdoc_test)
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rusttest-kernel: private rustc_target_flags = --extern alloc \
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--extern build_error --extern macros --extern bindings --extern uapi
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rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
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rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \
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rusttestlib-uapi FORCE
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$(call if_changed,rustc_test)
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$(call if_changed,rustc_test_library)
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+$(call if_changed,rustc_test)
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+$(call if_changed,rustc_test_library)
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ifdef CONFIG_CC_IS_CLANG
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bindgen_c_flags = $(c_flags)
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@ -396,7 +396,7 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
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# Therefore, to get `libmacros.so` automatically recompiled when the compiler
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# version changes, we add `core.o` as a dependency (even if it is not needed).
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$(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE
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$(call if_changed_dep,rustc_procmacro)
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+$(call if_changed_dep,rustc_procmacro)
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quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
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cmd_rustc_library = \
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@ -435,36 +435,36 @@ $(obj)/core.o: private skip_flags = -Dunreachable_pub
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$(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
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$(obj)/core.o: private rustc_target_flags = $(core-cfgs)
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$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
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$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/alloc.o: private skip_clippy = 1
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$(obj)/alloc.o: private skip_flags = -Dunreachable_pub
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$(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
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$(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/bindings.o: $(src)/bindings/lib.rs \
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$(obj)/compiler_builtins.o \
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$(obj)/bindings/bindings_generated.rs \
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$(obj)/bindings/bindings_helpers_generated.rs FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/uapi.o: $(src)/uapi/lib.rs \
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$(obj)/compiler_builtins.o \
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$(obj)/uapi/uapi_generated.rs FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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$(obj)/kernel.o: private rustc_target_flags = --extern alloc \
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--extern build_error --extern macros --extern bindings --extern uapi
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$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
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$(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE
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$(call if_changed_dep,rustc_library)
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+$(call if_changed_dep,rustc_library)
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endif # CONFIG_RUST
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@ -290,7 +290,7 @@ quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
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cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
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$(obj)/%.o: $(src)/%.rs FORCE
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$(call if_changed_dep,rustc_o_rs)
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+$(call if_changed_dep,rustc_o_rs)
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quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
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cmd_rustc_rsi_rs = \
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@ -298,19 +298,19 @@ quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
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command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
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$(obj)/%.rsi: $(src)/%.rs FORCE
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$(call if_changed_dep,rustc_rsi_rs)
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+$(call if_changed_dep,rustc_rsi_rs)
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quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
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cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
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$(obj)/%.s: $(src)/%.rs FORCE
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$(call if_changed_dep,rustc_s_rs)
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+$(call if_changed_dep,rustc_s_rs)
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quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
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cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
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$(obj)/%.ll: $(src)/%.rs FORCE
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$(call if_changed_dep,rustc_ll_rs)
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+$(call if_changed_dep,rustc_ll_rs)
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# Compile assembler sources (.S)
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# ---------------------------------------------------------------------------
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@ -156,7 +156,7 @@ quiet_cmd_host-rust = HOSTRUSTC $@
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cmd_host-rust = \
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$(HOSTRUSTC) $(hostrust_flags) --emit=link=$@ $<
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$(host-rust): $(obj)/%: $(src)/%.rs FORCE
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$(call if_changed_dep,host-rust)
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+$(call if_changed_dep,host-rust)
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targets += $(host-csingle) $(host-cmulti) $(host-cobjs) \
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$(host-cxxmulti) $(host-cxxobjs) $(host-rust)
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