History

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.

Miguel Ojeda committed 2 years ago

Commit ecab4111 parent e9441714 files · +31 −31Browse files

Unified · Split

4 files
  1. Makefile +2 −2
  2. rust/Makefile +24 −24
  3. scripts/Makefile.build +4 −4
  4. scripts/Makefile.host +1 −1
Makefile+2−2
@@ -1197,7 +1197,7 @@ prepare0: archprepare · 1196 unmodified lines
11971197 # All the preparing..
11981198 prepare: prepare0
11991199 ifdef CONFIG_RUST
1200− $(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
1200+ +$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
12011201 $(Q)$(MAKE) $(build)=rust
12021202 endif
12031203
@@ -1707,7 +1707,7 @@ $(DOC_TARGETS): · 503 unmodified lines
17071707 # "Is Rust available?" target
17081708 PHONY += rustavailable
17091709 rustavailable:
1710− $(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
1710+ +$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
17111711
17121712 # Documentation target
17131713 #
rust/Makefile+24−24
@@ -40,7 +40,7 @@ obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.o · 39 unmodified lines
4040 ifdef CONFIG_RUST
4141
4242 # `$(rust_flags)` is passed in case the user added `--sysroot`.
43−rustc_sysroot := $(shell $(RUSTC) $(rust_flags) --print sysroot)
43+rustc_sysroot := $(shell MAKEFLAGS= $(RUSTC) $(rust_flags) --print sysroot)
4444 rustc_host_target := $(shell $(RUSTC) --version --verbose | grep -F 'host: ' | cut -d' ' -f2)
4545 RUST_LIB_SRC ?= $(rustc_sysroot)/lib/rustlib/src/rust/library
4646
@@ -108,14 +108,14 @@ rustdoc-macros: private rustdoc_host = yes · 61 unmodified lines
108108 rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
109109 --extern proc_macro
110110 rustdoc-macros: $(src)/macros/lib.rs FORCE
111− $(call if_changed,rustdoc)
111+ +$(call if_changed,rustdoc)
112112
113113 rustdoc-core: private rustc_target_flags = $(core-cfgs)
114114 rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
115− $(call if_changed,rustdoc)
115+ +$(call if_changed,rustdoc)
116116
117117 rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
118− $(call if_changed,rustdoc)
118+ +$(call if_changed,rustdoc)
119119
120120 # We need to allow `rustdoc::broken_intra_doc_links` because some
121121 # `no_global_oom_handling` functions refer to non-`no_global_oom_handling`
@@ -124,7 +124,7 @@ rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE · 2 unmodified lines
124124 rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \
125125 -Arustdoc::broken_intra_doc_links
126126 rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
127− $(call if_changed,rustdoc)
127+ +$(call if_changed,rustdoc)
128128
129129 rustdoc-kernel: private rustc_target_flags = --extern alloc \
130130 --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
@@ -132,7 +132,7 @@ rustdoc-kernel: private rustc_target_flags = --extern alloc \ · 1 unmodified line
132132 rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
133133 rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
134134 $(obj)/bindings.o FORCE
135− $(call if_changed,rustdoc)
135+ +$(call if_changed,rustdoc)
136136
137137 quiet_cmd_rustc_test_library = RUSTC TL $<
138138 cmd_rustc_test_library = \
@@ -146,18 +146,18 @@ quiet_cmd_rustc_test_library = RUSTC TL $< · 7 unmodified lines
146146 --crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<
147147
148148 rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE
149− $(call if_changed,rustc_test_library)
149+ +$(call if_changed,rustc_test_library)
150150
151151 rusttestlib-macros: private rustc_target_flags = --extern proc_macro
152152 rusttestlib-macros: private rustc_test_library_proc = yes
153153 rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
154− $(call if_changed,rustc_test_library)
154+ +$(call if_changed,rustc_test_library)
155155
156156 rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE
157− $(call if_changed,rustc_test_library)
157+ +$(call if_changed,rustc_test_library)
158158
159159 rusttestlib-uapi: $(src)/uapi/lib.rs rusttest-prepare FORCE
160− $(call if_changed,rustc_test_library)
160+ +$(call if_changed,rustc_test_library)
161161
162162 quiet_cmd_rustdoc_test = RUSTDOC T $<
163163 cmd_rustdoc_test = \
@@ -189,7 +189,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $< · 25 unmodified lines
189189 $(src)/kernel/lib.rs $(obj)/kernel.o \
190190 $(objtree)/scripts/rustdoc_test_builder \
191191 $(objtree)/scripts/rustdoc_test_gen FORCE
192− $(call if_changed,rustdoc_test_kernel)
192+ +$(call if_changed,rustdoc_test_kernel)
193193
194194 # We cannot use `-Zpanic-abort-tests` because some tests are dynamic,
195195 # so for the moment we skip `-Cpanic=abort`.
@@ -254,21 +254,21 @@ quiet_cmd_rustsysroot = RUSTSYSROOT · 58 unmodified lines
254254 $(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib
255255
256256 rusttest-prepare: FORCE
257− $(call if_changed,rustsysroot)
257+ +$(call if_changed,rustsysroot)
258258
259259 rusttest-macros: private rustc_target_flags = --extern proc_macro
260260 rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
261261 rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
262− $(call if_changed,rustc_test)
263− $(call if_changed,rustdoc_test)
262+ +$(call if_changed,rustc_test)
263+ +$(call if_changed,rustdoc_test)
264264
265265 rusttest-kernel: private rustc_target_flags = --extern alloc \
266266 --extern build_error --extern macros --extern bindings --extern uapi
267267 rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
268268 rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \
269269 rusttestlib-uapi FORCE
270− $(call if_changed,rustc_test)
271− $(call if_changed,rustc_test_library)
270+ +$(call if_changed,rustc_test)
271+ +$(call if_changed,rustc_test_library)
272272
273273 ifdef CONFIG_CC_IS_CLANG
274274 bindgen_c_flags = $(c_flags)
@@ -396,7 +396,7 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@ · 121 unmodified lines
396396 # Therefore, to get `libmacros.so` automatically recompiled when the compiler
397397 # version changes, we add `core.o` as a dependency (even if it is not needed).
398398 $(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE
399− $(call if_changed_dep,rustc_procmacro)
399+ +$(call if_changed_dep,rustc_procmacro)
400400
401401 quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
402402 cmd_rustc_library = \
@@ -435,36 +435,36 @@ $(obj)/core.o: private skip_flags = -Dunreachable_pub · 32 unmodified lines
435435 $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
436436 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
437437 $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE
438− $(call if_changed_dep,rustc_library)
438+ +$(call if_changed_dep,rustc_library)
439439
440440 $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
441441 $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
442− $(call if_changed_dep,rustc_library)
442+ +$(call if_changed_dep,rustc_library)
443443
444444 $(obj)/alloc.o: private skip_clippy = 1
445445 $(obj)/alloc.o: private skip_flags = -Dunreachable_pub
446446 $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
447447 $(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
448− $(call if_changed_dep,rustc_library)
448+ +$(call if_changed_dep,rustc_library)
449449
450450 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
451− $(call if_changed_dep,rustc_library)
451+ +$(call if_changed_dep,rustc_library)
452452
453453 $(obj)/bindings.o: $(src)/bindings/lib.rs \
454454 $(obj)/compiler_builtins.o \
455455 $(obj)/bindings/bindings_generated.rs \
456456 $(obj)/bindings/bindings_helpers_generated.rs FORCE
457− $(call if_changed_dep,rustc_library)
457+ +$(call if_changed_dep,rustc_library)
458458
459459 $(obj)/uapi.o: $(src)/uapi/lib.rs \
460460 $(obj)/compiler_builtins.o \
461461 $(obj)/uapi/uapi_generated.rs FORCE
462− $(call if_changed_dep,rustc_library)
462+ +$(call if_changed_dep,rustc_library)
463463
464464 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
465465 --extern build_error --extern macros --extern bindings --extern uapi
466466 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
467467 $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE
468− $(call if_changed_dep,rustc_library)
468+ +$(call if_changed_dep,rustc_library)
469469
470470 endif # CONFIG_RUST
scripts/Makefile.build+4−4
@@ -290,7 +290,7 @@ quiet_cmd_rustc_o_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@ · 289 unmodified lines
290290 cmd_rustc_o_rs = $(rust_common_cmd) --emit=obj=$@ $<
291291
292292 $(obj)/%.o: $(src)/%.rs FORCE
293− $(call if_changed_dep,rustc_o_rs)
293+ +$(call if_changed_dep,rustc_o_rs)
294294
295295 quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
296296 cmd_rustc_rsi_rs = \
@@ -298,19 +298,19 @@ quiet_cmd_rustc_rsi_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@ · 1 unmodified line
298298 command -v $(RUSTFMT) >/dev/null && $(RUSTFMT) $@
299299
300300 $(obj)/%.rsi: $(src)/%.rs FORCE
301− $(call if_changed_dep,rustc_rsi_rs)
301+ +$(call if_changed_dep,rustc_rsi_rs)
302302
303303 quiet_cmd_rustc_s_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
304304 cmd_rustc_s_rs = $(rust_common_cmd) --emit=asm=$@ $<
305305
306306 $(obj)/%.s: $(src)/%.rs FORCE
307− $(call if_changed_dep,rustc_s_rs)
307+ +$(call if_changed_dep,rustc_s_rs)
308308
309309 quiet_cmd_rustc_ll_rs = $(RUSTC_OR_CLIPPY_QUIET) $(quiet_modtag) $@
310310 cmd_rustc_ll_rs = $(rust_common_cmd) --emit=llvm-ir=$@ $<
311311
312312 $(obj)/%.ll: $(src)/%.rs FORCE
313− $(call if_changed_dep,rustc_ll_rs)
313+ +$(call if_changed_dep,rustc_ll_rs)
314314
315315 # Compile assembler sources (.S)
316316 # ---------------------------------------------------------------------------
scripts/Makefile.host+1−1
@@ -156,7 +156,7 @@ quiet_cmd_host-rust = HOSTRUSTC $@ · 155 unmodified lines
156156 cmd_host-rust = \
157157 $(HOSTRUSTC) $(hostrust_flags) --emit=link=$@ $<
158158 $(host-rust): $(obj)/%: $(src)/%.rs FORCE
159− $(call if_changed_dep,host-rust)
159+ +$(call if_changed_dep,host-rust)
160160
161161 targets += $(host-csingle) $(host-cmulti) $(host-cobjs) \
162162 $(host-cxxmulti) $(host-cxxobjs) $(host-rust)