On Fri, Aug 21, 2020 at 12:02 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > Currently, you need to manually run scripts/gen_compile_commands.py > to create compile_commands.json. It parses all the .*.cmd files found > under the specified directory. > > If you rebuild the kernel over again without 'make clean', > .*.cmd files from older builds will create stale entries in > compile_commands.json. > > This commit wires up the compile_commands.json rule to Makefile, and > makes it parse only the .*.cmd files involved in the current build. > > Pass $(KBUILD_VMLINUX_OBJS), $(KBUILD_VMLINUX_LIBS), and modules.order > to the script. The objects or archives linked to vmlinux are listed in > $(KBUILD_VMLINUX_OBJS) or $(KBUILD_VMLINUX_LIBS). All the modules are > listed in modules.order. > > You can create compile_commands.json from Make: > > $ make -j$(nproc) CC=clang compile_commands.json > > You can also build vmlinux, modules, and compile_commands.json all > together in a single command: > > $ make -j$(nproc) CC=clang all compile_commands.json > > It works for M= builds as well. In this case, compile_commands.json > is created in the top directory of the external module. > > This is convenient, but it has a drawback; the coverage of the > compile_commands.json is reduced because only the objects linked to > vmlinux or modules are handled. For example, the following C files are > not included in the compile_commands.json: > > - Decompressor source files (arch/*/boot/) > - VDSO source files > - C files used to generate intermediates (e.g. kernel/bounds.c) > - Standalone host programs > > I think it is fine for most developers because our main interest is > the kernel-space code. > > If you want to cover all the compiled C files, please build the kernel > then run the script manually as before: > > $ make clean # if you want to delete stale .cmd files [optional] > $ make -j$(nproc) CC=clang > $ scripts/gen_compile_commands.json > > Here is a note for out-of-tree builds. 'make compile_commands.json' > works with O= option, but please notice compile_commands.json is > created in the object tree instead of the source tree. > > Some people may want to have compile_commands.json in the source tree > because Clang Tools searches for it through all parent paths of the > first input source file. > > However, you cannot do this for O= builds. Kbuild should never generate > any build artifact in the source tree when O= is given because the > source tree might be read-only. Any write attempt to the source tree > is monitored and the violation may be reported. See the commit log of > 8ef14c2c41d9. > > So, the only possible way is to create compile_commands.json in the > object tree, then specify '-p <build-path>' when you use clang-check, > clang-tidy, etc. > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- > > (no changes since v1) > > Makefile | 29 +++++++++++++++++++++++++---- > 1 file changed, 25 insertions(+), 4 deletions(-) > > diff --git a/Makefile b/Makefile > index 9cac6fde3479..65ed336a6de1 100644 > --- a/Makefile > +++ b/Makefile > @@ -635,7 +635,7 @@ endif > # in addition to whatever we do anyway. > # Just "make" or "make all" shall build modules as well > > -ifneq ($(filter all modules nsdeps,$(MAKECMDGOALS)),) > +ifneq ($(filter all modules nsdeps %compile_commands.json,$(MAKECMDGOALS)),) > KBUILD_MODULES := 1 > endif > > @@ -1464,7 +1464,8 @@ endif # CONFIG_MODULES > > # Directories & files removed with 'make clean' > CLEAN_FILES += include/ksym vmlinux.symvers \ > - modules.builtin modules.builtin.modinfo modules.nsdeps > + modules.builtin modules.builtin.modinfo modules.nsdeps \ > + compile_commands.json > > # Directories & files removed with 'make mrproper' > MRPROPER_FILES += include/config include/generated \ > @@ -1698,9 +1699,12 @@ KBUILD_MODULES := 1 > > build-dirs := $(KBUILD_EXTMOD) > PHONY += modules > -modules: descend > +modules: $(MODORDER) > $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost > > +$(MODORDER): descend > + @: ^ stuff like this I don't understand. But I understand the premise of the patch, the change in behavior, and the tradeoffs, so: Acked-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > + > PHONY += modules_install > modules_install: _emodinst_ _emodinst_post > > @@ -1714,8 +1718,12 @@ PHONY += _emodinst_post > _emodinst_post: _emodinst_ > $(call cmd,depmod) > > +compile_commands.json: $(extmod-prefix)compile_commands.json > +PHONY += compile_commands.json > + > clean-dirs := $(KBUILD_EXTMOD) > -clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps > +clean: rm-files := $(KBUILD_EXTMOD)/Module.symvers $(KBUILD_EXTMOD)/modules.nsdeps \ > + $(KBUILD_EXTMOD)/compile_commands.json > > PHONY += help > help: > @@ -1828,6 +1836,19 @@ nsdeps: export KBUILD_NSDEPS=1 > nsdeps: modules > $(Q)$(CONFIG_SHELL) $(srctree)/scripts/nsdeps > > +# Clang Tooling > +# --------------------------------------------------------------------------- > + > +quiet_cmd_gen_compile_commands = GEN $@ > + cmd_gen_compile_commands = $(PYTHON3) $< -a $(AR) -o $@ $(filter-out $<, $(real-prereqs)) > + > +$(extmod-prefix)compile_commands.json: scripts/gen_compile_commands.py \ > + $(if $(KBUILD_EXTMOD),,$(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)) \ > + $(if $(CONFIG_MODULES), $(MODORDER)) FORCE > + $(call if_changed,gen_compile_commands) > + > +targets += $(extmod-prefix)compile_commands.json > + > # Scripts to check various things for consistency > # --------------------------------------------------------------------------- > > -- > 2.25.1 > -- Thanks, ~Nick Desaulniers
