09bd7c75e5
Pull Kbuild updates from Masahiro Yamada:
"One of the most remarkable improvements in this cycle is, Kbuild is
now able to cache the result of shell commands. Some variables are
expensive to compute, for example, $(call cc-option,...) invokes the
compiler. It is not efficient to redo this computation every time,
even when we are not actually building anything. Kbuild creates a
hidden file ".cache.mk" that contains invoked shell commands and their
results. The speed-up should be noticeable.
Summary:
- Fix arch build issues (hexagon, sh)
- Clean up various Makefiles and scripts
- Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles
- Cache variables that are expensive to compute
- Improve cc-ldopton and ld-option for Clang
- Optimize output directory creation"
* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
sh: decompressor: add shipped files to .gitignore
frv: .gitignore: ignore vmlinux.lds
selinux: remove unnecessary assignment to subdir-
kbuild: specify FORCE in Makefile.headersinst as .PHONY target
kbuild: remove redundant mkdir from ./Kbuild
kbuild: optimize object directory creation for incremental build
kbuild: create object directories simpler and faster
kbuild: filter-out PHONY targets from "targets"
kbuild: remove redundant $(wildcard ...) for cmd_files calculation
kbuild: create directory for make cache only when necessary
sh: select KBUILD_DEFCONFIG depending on ARCH
kbuild: fix linker feature test macros when cross compiling with Clang
kbuild: shrink .cache.mk when it exceeds 1000 lines
kbuild: do not call cc-option before KBUILD_CFLAGS initialization
kbuild: Cache a few more calls to the compiler
kbuild: Add a cache for generated variables
kbuild: add forward declaration of default target to Makefile.asm-generic
kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
...
157 lines
5.5 KiB
Makefile
157 lines
5.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ===========================================================================
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# Module versions
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# ===========================================================================
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#
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# Stage one of module building created the following:
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# a) The individual .o files used for the module
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# b) A <module>.o file which is the .o files above linked together
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# c) A <module>.mod file in $(MODVERDIR)/, listing the name of the
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# the preliminary <module>.o file, plus all .o files
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# Stage 2 is handled by this file and does the following
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# 1) Find all modules from the files listed in $(MODVERDIR)/
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# 2) modpost is then used to
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# 3) create one <module>.mod.c file pr. module
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# 4) create one Module.symvers file with CRC for all exported symbols
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# 5) compile all <module>.mod.c files
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# 6) final link of the module to a <module.ko> file
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# Step 3 is used to place certain information in the module's ELF
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# section, including information such as:
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# Version magic (see include/linux/vermagic.h for full details)
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# - Kernel release
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# - SMP is CONFIG_SMP
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# - PREEMPT is CONFIG_PREEMPT
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# - GCC Version
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# Module info
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# - Module version (MODULE_VERSION)
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# - Module alias'es (MODULE_ALIAS)
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# - Module license (MODULE_LICENSE)
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# - See include/linux/module.h for more details
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# Step 4 is solely used to allow module versioning in external modules,
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# where the CRC of each module is retrieved from the Module.symvers file.
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# KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined
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# symbols in the final module linking stage
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# KBUILD_MODPOST_NOFINAL can be set to skip the final link of modules.
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# This is solely useful to speed up test compiles
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PHONY := _modpost
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_modpost: __modpost
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include include/config/auto.conf
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include scripts/Kbuild.include
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# When building external modules load the Kbuild file to retrieve EXTRA_SYMBOLS info
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ifneq ($(KBUILD_EXTMOD),)
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# set src + obj - they may be used when building the .mod.c file
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obj := $(KBUILD_EXTMOD)
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src := $(obj)
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# Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
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include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
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$(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
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endif
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include scripts/Makefile.lib
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kernelsymfile := $(objtree)/Module.symvers
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modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
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# Step 1), find all modules listed in $(MODVERDIR)/
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MODLISTCMD := find $(MODVERDIR) -name '*.mod' | xargs -r grep -h '\.ko$$' | sort -u
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__modules := $(shell $(MODLISTCMD))
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modules := $(patsubst %.o,%.ko, $(wildcard $(__modules:.ko=.o)))
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# Stop after building .o files if NOFINAL is set. Makes compile tests quicker
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_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules))
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# Step 2), invoke modpost
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# Includes step 3,4
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modpost = scripts/mod/modpost \
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$(if $(CONFIG_MODVERSIONS),-m) \
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$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a,) \
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$(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
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$(if $(KBUILD_EXTMOD),-I $(modulesymfile)) \
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$(if $(KBUILD_EXTRA_SYMBOLS), $(patsubst %, -e %,$(KBUILD_EXTRA_SYMBOLS))) \
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$(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
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$(if $(CONFIG_DEBUG_SECTION_MISMATCH),,-S) \
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$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
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$(if $(KBUILD_EXTMOD)$(KBUILD_MODPOST_WARN),-w)
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MODPOST_OPT=$(subst -i,-n,$(filter -i,$(MAKEFLAGS)))
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# We can go over command line length here, so be careful.
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quiet_cmd_modpost = MODPOST $(words $(filter-out vmlinux FORCE, $^)) modules
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cmd_modpost = $(MODLISTCMD) | sed 's/\.ko$$/.o/' | $(modpost) $(MODPOST_OPT) -s -T -
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PHONY += __modpost
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__modpost: $(modules:.ko=.o) FORCE
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$(call cmd,modpost) $(wildcard vmlinux)
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quiet_cmd_kernel-mod = MODPOST $@
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cmd_kernel-mod = $(modpost) $@
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vmlinux.o: FORCE
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$(call cmd,kernel-mod)
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# Declare generated files as targets for modpost
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$(modules:.ko=.mod.c): __modpost ;
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# Step 5), compile all *.mod.c files
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# modname is set to make c_flags define KBUILD_MODNAME
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modname = $(notdir $(@:.mod.o=))
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quiet_cmd_cc_o_c = CC $@
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cmd_cc_o_c = $(CC) $(c_flags) $(KBUILD_CFLAGS_MODULE) $(CFLAGS_MODULE) \
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-c -o $@ $<
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$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
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$(call if_changed_dep,cc_o_c)
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targets += $(modules:.ko=.mod.o)
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ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
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# Step 6), final link of the modules with optional arch pass after final link
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quiet_cmd_ld_ko_o = LD [M] $@
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cmd_ld_ko_o = \
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$(LD) -r $(LDFLAGS) \
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$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
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-o $@ $(filter-out FORCE,$^) ; \
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$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
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$(modules): %.ko :%.o %.mod.o FORCE
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+$(call if_changed,ld_ko_o)
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targets += $(modules)
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# Add FORCE to the prequisites of a target to force it to be always rebuilt.
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# ---------------------------------------------------------------------------
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PHONY += FORCE
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FORCE:
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# Read all saved command lines and dependencies for the $(targets) we
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# may be building above, using $(if_changed{,_dep}). As an
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# optimization, we don't need to read them if the target does not
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# exist, we will rebuild anyway in that case.
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cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
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ifneq ($(cmd_files),)
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include $(cmd_files)
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endif
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# Declare the contents of the .PHONY variable as phony. We keep that
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# information in a variable se we can use it in if_changed and friends.
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.PHONY: $(PHONY)
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