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https://github.com/torvalds/linux
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5573b4daa2
When there is a missing input file (vmlinux.o or Module.symvers), you are likely to get a ton of unresolved symbols. Currently, Kbuild automatically adds the -w option to allow module builds to continue with warnings instead of errors. This may not be what the user expects because it is generally more useful to catch all possible issues at build time instead of at run time. Let's not do what the user did not ask. If you still want to build modules anyway, you can proceed by explicitly setting KBUILD_MODPOST_WARN=1. Since you may miss a real issue, you need to be aware of what you are doing. Suggested-by: William McVicker <willmcvicker@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Will McVicker <willmcvicker@google.com>
147 lines
4.4 KiB
Makefile
147 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 $(srctree)/scripts/Kbuild.include
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MODPOST = scripts/mod/modpost
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modpost-args = \
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$(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 $(KBUILD_MODPOST_WARN),-w) \
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$(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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modpost-deps := $(MODPOST)
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# 'make -i -k' ignores compile errors, and builds as many modules as possible.
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ifneq ($(findstring i,$(filter-out --%,$(MAKEFLAGS))),)
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modpost-args += -n
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endif
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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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ifdef KBUILD_MODULES
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modpost-args += -T $(MODORDER)
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modpost-deps += $(MODORDER)
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endif
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ifeq ($(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 $${f} in \
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*libgcc.a) ;; \
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*) $(AR) t $${f} ;; \
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esac \
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done > $@
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targets += .vmlinux.objs
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.vmlinux.objs: vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
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$(call if_changed,vmlinux_objs)
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ifeq ($(wildcard vmlinux.o),)
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missing-input := vmlinux.o
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output-symdump := modules-only.symvers
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else
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modpost-args += vmlinux.o
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modpost-deps += vmlinux.o
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output-symdump := $(if $(KBUILD_MODULES), Module.symvers, vmlinux.symvers)
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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 $(kbuild-file)
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output-symdump := $(KBUILD_EXTMOD)/Module.symvers
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ifeq ($(wildcard Module.symvers),)
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missing-input := Module.symvers
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else
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modpost-args += -i Module.symvers
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modpost-deps += Module.symvers
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endif
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modpost-args += -e $(addprefix -i , $(KBUILD_EXTRA_SYMBOLS))
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endif # ($(KBUILD_EXTMOD),)
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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: $(missing-input) is missing."; \
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echo >&2 " Modules may not have dependencies or modversions."; \
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echo >&2 " You may get many unresolved symbol errors."; \
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echo >&2 " You can set KBUILD_MODPOST_WARN=1 to turn errors into warning"; \
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echo >&2 " if you want to proceed at your own risk.";) \
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$(MODPOST) $(modpost-args)
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targets += $(output-symdump)
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$(output-symdump): $(modpost-deps) FORCE
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$(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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