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f73edc8951
Currently, modpost is executed twice; first for vmlinux, second
for modules.
This commit merges them.
Current build flow
==================
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux
4) link vmlinux
5) modpost for modules
6) link modules (*.ko)
The build steps 1) through 6) are serialized, that is, modules are
built after vmlinux. You do not get benefits of parallel builds when
scripts/link-vmlinux.sh is being run.
New build flow
==============
1) build obj-y and obj-m objects
2) link vmlinux.o
3) modpost for vmlinux and modules
4a) link vmlinux
4b) link modules (*.ko)
In the new build flow, modpost is invoked just once.
vmlinux and modules are built in parallel. One exception is
CONFIG_DEBUG_INFO_BTF_MODULES=y, where modules depend on vmlinux.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
136 lines
4.4 KiB
Makefile
136 lines
4.4 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, listing the name of the preliminary <module>.o file,
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# plus all .o files
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# d) modules.order, which lists all the modules
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# Stage 2 is handled by this file and does the following
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# 1) Find all modules listed in modules.order
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# 2) modpost is then used to
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# 3) create one <module>.mod.c file per module
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# 4) create one Module.symvers file with CRC for all exported symbols
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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[_RT]
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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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PHONY := __modpost
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__modpost:
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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MODPOST = scripts/mod/modpost \
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$(if $(CONFIG_MODVERSIONS),-m) \
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$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
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$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
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$(if $(KBUILD_NSDEPS),-d $(MODULES_NSDEPS)) \
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$(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N) \
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-o $@
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# 'make -i -k' ignores compile errors, and builds as many modules as possible.
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ifneq ($(findstring i,$(filter-out --%,$(MAKEFLAGS))),)
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MODPOST += -n
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endif
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ifeq ($(KBUILD_EXTMOD),)
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# Generate the list of in-tree objects in vmlinux
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# ---------------------------------------------------------------------------
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# This is used to retrieve symbol versions generated by genksyms.
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ifdef CONFIG_MODVERSIONS
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vmlinux.symvers Module.symvers: .vmlinux.objs
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endif
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# Ignore libgcc.a
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# Some architectures do '$(CC) --print-libgcc-file-name' to borrow libgcc.a
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# from the toolchain, but there is no EXPORT_SYMBOL in it.
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quiet_cmd_vmlinux_objs = GEN $@
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cmd_vmlinux_objs = \
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for f in $(real-prereqs); do \
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case $${f} in \
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*libgcc.a) ;; \
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*.a) $(AR) t $${f} ;; \
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*) echo $${f} ;; \
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esac \
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done > $@
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targets += .vmlinux.objs
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.vmlinux.objs: $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS) FORCE
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$(call if_changed,vmlinux_objs)
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vmlinux.o-if-present := $(wildcard vmlinux.o)
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output-symdump := vmlinux.symvers
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ifdef KBUILD_MODULES
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output-symdump := $(if $(vmlinux.o-if-present), Module.symvers, modules-only.symvers)
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missing-input := $(filter-out $(vmlinux.o-if-present),vmlinux.o)
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endif
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else
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# set src + obj - they may be used in the modules's Makefile
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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 $(or $(wildcard $(src)/Kbuild), $(src)/Makefile)
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module.symvers-if-present := $(wildcard Module.symvers)
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output-symdump := $(KBUILD_EXTMOD)/Module.symvers
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missing-input := $(filter-out $(module.symvers-if-present), Module.symvers)
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MODPOST += -e $(addprefix -i ,$(module.symvers-if-present) $(KBUILD_EXTRA_SYMBOLS))
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endif # ($(KBUILD_EXTMOD),)
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ifneq ($(KBUILD_MODPOST_WARN)$(missing-input),)
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MODPOST += -w
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endif
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modorder-if-needed := $(if $(KBUILD_MODULES), $(MODORDER))
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# Read out modules.order to pass in modpost.
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# Otherwise, allmodconfig would fail with "Argument list too long".
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quiet_cmd_modpost = MODPOST $@
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cmd_modpost = \
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$(if $(missing-input), \
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echo >&2 "WARNING: $(missing-input) is missing."; \
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echo >&2 " Modules may not have dependencies or modversions."; \
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echo >&2 " You may get many unresolved symbol warnings.";) \
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sed 's/ko$$/o/' $(or $(modorder-if-needed), /dev/null) | $(MODPOST) $(vmlinux.o-if-present) -T -
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targets += $(output-symdump)
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$(output-symdump): $(modorder-if-needed) $(vmlinux.o-if-present) $(moudle.symvers-if-present) FORCE
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$(call if_changed,modpost)
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__modpost: $(output-symdump)
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PHONY += FORCE
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FORCE:
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existing-targets := $(wildcard $(sort $(targets)))
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-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
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.PHONY: $(PHONY)
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