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# SPDX-License-Identifier: GPL-2.0 # Where to place rustdoc generated documentationrustdoc_output := $(objtree)/Documentation/output/rust/rustdoc obj-$(CONFIG_RUST) += core.o compiler_builtins.oalways-$(CONFIG_RUST) += exports_core_generated.h # Missing prototypes are expected in the helpers since these are exported# for Rust only, thus there is no header nor prototypes.obj-$(CONFIG_RUST) += helpers.oCFLAGS_REMOVE_helpers.o = -Wmissing-prototypes -Wmissing-declarations always-$(CONFIG_RUST) += libmacros.sono-clean-files += libmacros.so always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rsobj-$(CONFIG_RUST) += alloc.o bindings.o kernel.oalways-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \    exports_kernel_generated.h always-$(CONFIG_RUST) += uapi/uapi_generated.rsobj-$(CONFIG_RUST) += uapi.o ifdef CONFIG_RUST_BUILD_ASSERT_ALLOWobj-$(CONFIG_RUST) += build_error.oelsealways-$(CONFIG_RUST) += build_error.oendif obj-$(CONFIG_RUST) += exports.o always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.rsalways-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.c obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.oobj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.o # Avoids running `$(RUSTC)` for the sysroot when it may not be available.ifdef CONFIG_RUST # `$(rust_flags)` is passed in case the user added `--sysroot`.rustc_sysroot := $(shell MAKEFLAGS= $(RUSTC) $(rust_flags) --print sysroot)rustc_host_target := $(shell $(RUSTC) --version --verbose | grep -F 'host: ' | cut -d' ' -f2)RUST_LIB_SRC ?= $(rustc_sysroot)/lib/rustlib/src/rust/library ifeq ($(quiet),silent_)cargo_quiet=-qrust_test_quiet=-qrustdoc_test_quiet=--test-args -qrustdoc_test_kernel_quiet=>/dev/nullelse ifeq ($(quiet),quiet_)rust_test_quiet=-qrustdoc_test_quiet=--test-args -qrustdoc_test_kernel_quiet=>/dev/nullelsecargo_quiet=--verboseendif core-cfgs = \    --cfg no_fp_fmt_parse alloc-cfgs = \    --cfg no_borrow \    --cfg no_fmt \    --cfg no_global_oom_handling \    --cfg no_macros \    --cfg no_rc \    --cfg no_str \    --cfg no_string \    --cfg no_sync \    --cfg no_thin quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<      cmd_rustdoc = \	OBJTREE=$(abspath $(objtree)) \	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \		$(rustc_target_flags) -L$(objtree)/$(obj) \		--output $(rustdoc_output) \		--crate-name $(subst rustdoc-,,$@) \		$(if $(rustdoc_host),,--sysroot=/dev/null) \		@$(objtree)/include/generated/rustc_cfg $< # The `html_logo_url` and `html_favicon_url` forms of the `doc` attribute# can be used to specify a custom logo. However:#   - The given value is used as-is, thus it cannot be relative or a local file#     (unlike the non-custom case) since the generated docs have subfolders.#   - It requires adding it to every crate.#   - It requires changing `core` which comes from the sysroot.## Using `-Zcrate-attr` would solve the last two points, but not the first.# The https://github.com/rust-lang/rfcs/pull/3226 RFC suggests two new# command-like flags to solve the issue. Meanwhile, we use the non-custom case# and then retouch the generated files.rustdoc: rustdoc-core rustdoc-macros rustdoc-compiler_builtins \    rustdoc-alloc rustdoc-kernel	$(Q)cp $(srctree)/Documentation/images/logo.svg $(rustdoc_output)/static.files/	$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(rustdoc_output)/static.files/	$(Q)find $(rustdoc_output) -name '*.html' -type f -print0 | xargs -0 sed -Ei \		-e 's:rust-logo-[0-9a-f]+\.svg:logo.svg:g' \		-e 's:favicon-[0-9a-f]+\.svg:logo.svg:g' \		-e 's:<link rel="alternate icon" type="image/png" href="[/.]+/static\.files/favicon-(16x16|32x32)-[0-9a-f]+\.png">::g' \		-e 's:<a href="srctree/([^"]+)">:<a href="$(realpath $(srctree))/\1">:g'	$(Q)for f in $(rustdoc_output)/static.files/rustdoc-*.css; do \		echo ".logo-container > img { object-fit: contain; }" >> $$f; done rustdoc-macros: private rustdoc_host = yesrustdoc-macros: private rustc_target_flags = --crate-type proc-macro \    --extern proc_macrorustdoc-macros: $(src)/macros/lib.rs FORCE	+$(call if_changed,rustdoc) rustdoc-core: private rustc_target_flags = $(core-cfgs)rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE	+$(call if_changed,rustdoc) rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE	+$(call if_changed,rustdoc) # We need to allow `rustdoc::broken_intra_doc_links` because some# `no_global_oom_handling` functions refer to non-`no_global_oom_handling`# functions. Ideally `rustdoc` would have a way to distinguish broken links# due to things that are "configured out" vs. entirely non-existing ones.rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \    -Arustdoc::broken_intra_doc_linksrustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE	+$(call if_changed,rustdoc) rustdoc-kernel: private rustc_target_flags = --extern alloc \    --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \    --extern bindings --extern uapirustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \    rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \    $(obj)/bindings.o FORCE	+$(call if_changed,rustdoc) quiet_cmd_rustc_test_library = RUSTC TL $<      cmd_rustc_test_library = \	OBJTREE=$(abspath $(objtree)) \	$(RUSTC) $(rust_common_flags) \		@$(objtree)/include/generated/rustc_cfg $(rustc_target_flags) \		--crate-type $(if $(rustc_test_library_proc),proc-macro,rlib) \		--out-dir $(objtree)/$(obj)/test --cfg testlib \		--sysroot $(objtree)/$(obj)/test/sysroot \		-L$(objtree)/$(obj)/test \		--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $< rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE	+$(call if_changed,rustc_test_library) rusttestlib-macros: private rustc_target_flags = --extern proc_macrorusttestlib-macros: private rustc_test_library_proc = yesrusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE	+$(call if_changed,rustc_test_library) rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE	+$(call if_changed,rustc_test_library) rusttestlib-uapi: $(src)/uapi/lib.rs rusttest-prepare FORCE	+$(call if_changed,rustc_test_library) quiet_cmd_rustdoc_test = RUSTDOC T $<      cmd_rustdoc_test = \	OBJTREE=$(abspath $(objtree)) \	$(RUSTDOC) --test $(rust_common_flags) \		@$(objtree)/include/generated/rustc_cfg \		$(rustc_target_flags) $(rustdoc_test_target_flags) \		--sysroot $(objtree)/$(obj)/test/sysroot $(rustdoc_test_quiet) \		-L$(objtree)/$(obj)/test --output $(rustdoc_output) \		--crate-name $(subst rusttest-,,$@) $< quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<      cmd_rustdoc_test_kernel = \	rm -rf $(objtree)/$(obj)/test/doctests/kernel; \	mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \	OBJTREE=$(abspath $(objtree)) \	$(RUSTDOC) --test $(rust_flags) \		-L$(objtree)/$(obj) --extern alloc --extern kernel \		--extern build_error --extern macros \		--extern bindings --extern uapi \		--no-run --crate-name kernel -Zunstable-options \		--sysroot=/dev/null \		--test-builder $(objtree)/scripts/rustdoc_test_builder \		$< $(rustdoc_test_kernel_quiet); \	$(objtree)/scripts/rustdoc_test_gen %/doctests_kernel_generated.rs %/doctests_kernel_generated_kunit.c: \    $(src)/kernel/lib.rs $(obj)/kernel.o \    $(objtree)/scripts/rustdoc_test_builder \    $(objtree)/scripts/rustdoc_test_gen FORCE	+$(call if_changed,rustdoc_test_kernel) # We cannot use `-Zpanic-abort-tests` because some tests are dynamic,# so for the moment we skip `-Cpanic=abort`.quiet_cmd_rustc_test = RUSTC T  $<      cmd_rustc_test = \	OBJTREE=$(abspath $(objtree)) \	$(RUSTC) --test $(rust_common_flags) \		@$(objtree)/include/generated/rustc_cfg \		$(rustc_target_flags) --out-dir $(objtree)/$(obj)/test \		--sysroot $(objtree)/$(obj)/test/sysroot \		-L$(objtree)/$(obj)/test \		--crate-name $(subst rusttest-,,$@) $<; \	$(objtree)/$(obj)/test/$(subst rusttest-,,$@) $(rust_test_quiet) \		$(rustc_test_run_flags) rusttest: rusttest-macros rusttest-kernel # This prepares a custom sysroot with our custom `alloc` instead of# the standard one.## This requires several hacks:#   - Unlike `core` and `alloc`, `std` depends on more than a dozen crates,#     including third-party crates that need to be downloaded, plus custom#     `build.rs` steps. Thus hardcoding things here is not maintainable.#   - `cargo` knows how to build the standard library, but it is an unstable#     feature so far (`-Zbuild-std`).#   - `cargo` only considers the use case of building the standard library#     to use it in a given package. Thus we need to create a dummy package#     and pick the generated libraries from there.#   - Since we only keep a subset of upstream `alloc` in-tree, we need#     to recreate it on the fly by putting our sources on top.#   - The usual ways of modifying the dependency graph in `cargo` do not seem#     to apply for the `-Zbuild-std` steps, thus we have to mislead it#     by modifying the sources in the sysroot.#   - To avoid messing with the user's Rust installation, we create a clone#     of the sysroot. However, `cargo` ignores `RUSTFLAGS` in the `-Zbuild-std`#     steps, thus we use a wrapper binary passed via `RUSTC` to pass the flag.## In the future, we hope to avoid the whole ordeal by either:#   - Making the `test` crate not depend on `std` (either improving upstream#     or having our own custom crate).#   - Making the tests run in kernel space (requires the previous point).#   - Making `std` and friends be more like a "normal" crate, so that#     `-Zbuild-std` and related hacks are not needed.quiet_cmd_rustsysroot = RUSTSYSROOT      cmd_rustsysroot = \	rm -rf $(objtree)/$(obj)/test; \	mkdir -p $(objtree)/$(obj)/test; \	cp -a $(rustc_sysroot) $(objtree)/$(obj)/test/sysroot; \	cp -r $(srctree)/$(src)/alloc/* \		$(objtree)/$(obj)/test/sysroot/lib/rustlib/src/rust/library/alloc/src; \	echo '\#!/bin/sh' > $(objtree)/$(obj)/test/rustc_sysroot; \	echo "$(RUSTC) --sysroot=$(abspath $(objtree)/$(obj)/test/sysroot) \"\$$@\"" \		>> $(objtree)/$(obj)/test/rustc_sysroot; \	chmod u+x $(objtree)/$(obj)/test/rustc_sysroot; \	$(CARGO) -q new $(objtree)/$(obj)/test/dummy; \	RUSTC=$(objtree)/$(obj)/test/rustc_sysroot $(CARGO) $(cargo_quiet) \		test -Zbuild-std --target $(rustc_host_target) \		--manifest-path $(objtree)/$(obj)/test/dummy/Cargo.toml; \	rm $(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib/*; \	cp $(objtree)/$(obj)/test/dummy/target/$(rustc_host_target)/debug/deps/* \		$(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib rusttest-prepare: FORCE	+$(call if_changed,rustsysroot) rusttest-macros: private rustc_target_flags = --extern proc_macrorusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macrorusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE	+$(call if_changed,rustc_test)	+$(call if_changed,rustdoc_test) rusttest-kernel: private rustc_target_flags = --extern alloc \    --extern build_error --extern macros --extern bindings --extern uapirusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \    rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \    rusttestlib-uapi FORCE	+$(call if_changed,rustc_test)	+$(call if_changed,rustc_test_library) ifdef CONFIG_CC_IS_CLANGbindgen_c_flags = $(c_flags)else# bindgen relies on libclang to parse C. Ideally, bindgen would support a GCC# plugin backend and/or the Clang driver would be perfectly compatible with GCC.## For the moment, here we are tweaking the flags on the fly. This is a hack,# and some kernel configurations may not work (e.g. `GCC_PLUGIN_RANDSTRUCT`# if we end up using one of those structs).bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \	-mskip-rax-setup -mgeneral-regs-only -msign-return-address=% \	-mindirect-branch=thunk-extern -mindirect-branch-register \	-mfunction-return=thunk-extern -mrecord-mcount -mabi=lp64 \	-mindirect-branch-cs-prefix -mstack-protector-guard% -mtraceback=no \	-mno-pointers-to-nested-functions -mno-string \	-mno-strict-align -mstrict-align \	-fconserve-stack -falign-jumps=% -falign-loops=% \	-femit-struct-debug-baseonly -fno-ipa-cp-clone -fno-ipa-sra \	-fno-partial-inlining -fplugin-arg-arm_ssp_per_task_plugin-% \	-fno-reorder-blocks -fno-allow-store-data-races -fasan-shadow-offset=% \	-fzero-call-used-regs=% -fno-stack-clash-protection \	-fno-inline-functions-called-once -fsanitize=bounds-strict \	-fstrict-flex-arrays=% \	--param=% --param asan-% # Derived from `scripts/Makefile.clang`.BINDGEN_TARGET_x86	:= x86_64-linux-gnuBINDGEN_TARGET_arm64	:= aarch64-linux-gnuBINDGEN_TARGET		:= $(BINDGEN_TARGET_$(SRCARCH)) # All warnings are inhibited since GCC builds are very experimental,# many GCC warnings are not supported by Clang, they may only appear in# some configurations, with new GCC versions, etc.bindgen_extra_c_flags = -w --target=$(BINDGEN_TARGET) # Auto variable zero-initialization requires an additional special option with# clang that is going to be removed sometime in the future (likely in# clang-18), so make sure to pass this option only if clang supports it# (libclang major version < 16).## https://github.com/llvm/llvm-project/issues/44842# https://github.com/llvm/llvm-project/blob/llvmorg-16.0.0-rc2/clang/docs/ReleaseNotes.rst#deprecated-compiler-flagsifdef CONFIG_INIT_STACK_ALL_ZEROlibclang_maj_ver=$(shell $(BINDGEN) $(srctree)/scripts/rust_is_available_bindgen_libclang.h 2>&1 | sed -ne 's/.*clang version \([0-9]*\).*/\1/p')ifeq ($(shell expr $(libclang_maj_ver) \< 16), 1)bindgen_extra_c_flags += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clangendifendif bindgen_c_flags = $(filter-out $(bindgen_skip_c_flags), $(c_flags)) \	$(bindgen_extra_c_flags)endif ifdef CONFIG_LTObindgen_c_flags_lto = $(filter-out $(CC_FLAGS_LTO), $(bindgen_c_flags))elsebindgen_c_flags_lto = $(bindgen_c_flags)endif bindgen_c_flags_final = $(bindgen_c_flags_lto) -D__BINDGEN__ quiet_cmd_bindgen = BINDGEN $@      cmd_bindgen = \	$(BINDGEN) $< $(bindgen_target_flags) \		--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \		--no-debug '.*' \		-o $@ -- $(bindgen_c_flags_final) -DMODULE \		$(bindgen_target_cflags) $(bindgen_target_extra) $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \    $(shell grep -Ev '^#|^$$' $(srctree)/$(src)/bindgen_parameters)$(obj)/bindings/bindings_generated.rs: private bindgen_target_extra = ; \    sed -Ei 's/pub const RUST_CONST_HELPER_([a-zA-Z0-9_]*)/pub const \1/g' $@$(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \    $(src)/bindgen_parameters FORCE	$(call if_changed_dep,bindgen) $(obj)/uapi/uapi_generated.rs: private bindgen_target_flags = \    $(shell grep -Ev '^#|^$$' $(srctree)/$(src)/bindgen_parameters)$(obj)/uapi/uapi_generated.rs: $(src)/uapi/uapi_helper.h \    $(src)/bindgen_parameters FORCE	$(call if_changed_dep,bindgen) # See `CFLAGS_REMOVE_helpers.o` above. In addition, Clang on C does not warn# with `-Wmissing-declarations` (unlike GCC), so it is not strictly needed here# given it is `libclang`; but for consistency, future Clang changes and/or# a potential future GCC backend for `bindgen`, we disable it too.$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_flags = \    --blocklist-type '.*' --allowlist-var '' \    --allowlist-function 'rust_helper_.*'$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_cflags = \    -I$(objtree)/$(obj) -Wno-missing-prototypes -Wno-missing-declarations$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ; \    sed -Ei 's/pub fn rust_helper_([a-zA-Z0-9_]*)/#[link_name="rust_helper_\1"]\n    pub fn \1/g' $@$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers.c FORCE	$(call if_changed_dep,bindgen) quiet_cmd_exports = EXPORTS $@      cmd_exports = \	$(NM) -p --defined-only $< \		| awk '/ (T|R|D) / {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@ $(obj)/exports_core_generated.h: $(obj)/core.o FORCE	$(call if_changed,exports) $(obj)/exports_alloc_generated.h: $(obj)/alloc.o FORCE	$(call if_changed,exports) $(obj)/exports_bindings_generated.h: $(obj)/bindings.o FORCE	$(call if_changed,exports) $(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE	$(call if_changed,exports) quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@      cmd_rustc_procmacro = \	$(RUSTC_OR_CLIPPY) $(rust_common_flags) \		-Clinker-flavor=gcc -Clinker=$(HOSTCC) \		-Clink-args='$(call escsq,$(KBUILD_HOSTLDFLAGS))' \		--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \		--crate-type proc-macro \		--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 $(obj)/core.o FORCE	+$(call if_changed_dep,rustc_procmacro) quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@      cmd_rustc_library = \	OBJTREE=$(abspath $(objtree)) \	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \		$(filter-out $(skip_flags),$(rust_flags) $(rustc_target_flags)) \		--emit=dep-info=$(depfile) --emit=obj=$@ \		--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \		--crate-type rlib -L$(objtree)/$(obj) \		--crate-name $(patsubst %.o,%,$(notdir $@)) $< \		--sysroot=/dev/null \	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@) rust-analyzer:	$(Q)$(srctree)/scripts/generate_rust_analyzer.py \		--cfgs='core=$(core-cfgs)' --cfgs='alloc=$(alloc-cfgs)' \		$(realpath $(srctree)) $(realpath $(objtree)) \		$(RUST_LIB_SRC) $(KBUILD_EXTMOD) > \		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/rust-project.json redirect-intrinsics = \	__addsf3 __eqsf2 __gesf2 __lesf2 __ltsf2 __mulsf3 __nesf2 __unordsf2 \	__adddf3 __ledf2 __ltdf2 __muldf3 __unorddf2 \	__muloti4 __multi3 \	__udivmodti4 __udivti3 __umodti3 ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)	# These intrinsics are defined for ARM64 and RISCV64	redirect-intrinsics += \		__ashrti3 \		__ashlti3 __lshrti3endif $(obj)/core.o: private skip_clippy = 1$(obj)/core.o: private skip_flags = -Dunreachable_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: $(RUST_LIB_SRC)/core/src/lib.rs FORCE	+$(call if_changed_dep,rustc_library)ifneq ($(or $(CONFIG_X86_64),$(CONFIG_LOONGARCH)),)$(obj)/core.o: scripts/target.jsonendif $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE	+$(call if_changed_dep,rustc_library) $(obj)/alloc.o: private skip_clippy = 1$(obj)/alloc.o: private skip_flags = -Dunreachable_pub$(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)$(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE	+$(call if_changed_dep,rustc_library) $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE	+$(call if_changed_dep,rustc_library) $(obj)/bindings.o: $(src)/bindings/lib.rs \    $(obj)/compiler_builtins.o \    $(obj)/bindings/bindings_generated.rs \    $(obj)/bindings/bindings_helpers_generated.rs FORCE	+$(call if_changed_dep,rustc_library) $(obj)/uapi.o: $(src)/uapi/lib.rs \    $(obj)/compiler_builtins.o \    $(obj)/uapi/uapi_generated.rs FORCE	+$(call if_changed_dep,rustc_library) $(obj)/kernel.o: private rustc_target_flags = --extern alloc \    --extern build_error --extern macros --extern bindings --extern uapi$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \    $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE	+$(call if_changed_dep,rustc_library) endif # CONFIG_RUST