7d5e1de98e
When KBUILD_MIXED_TREE points to the output folder of another kernel's build output, Kbuild can compile a complete kernel tree's modules against that other kernel tree's vmlinux. This is useful when two kernel trees exist: a "Generic Kernel Image" tree and a "device kernel" tree. Both trees are complete kernel source trees, and the "Generic Kernel Image" should provide the kernel Image and device kernel tree provides device driver modules. To accomplish this, references to vmlinux.symvers in the device kernel should point to the generic kernel's vmlinux.symvers and the device kernel should skip compilation of built-in files. Bug: 178469391 Change-Id: I614f3e87519236c4e2c5da74937cb0ecd98a278a Signed-off-by: Elliot Berman <eberman@codeaurora.org> Signed-off-by: Giuliano Procida <gprocida@google.com>
175 lines
5.5 KiB
Makefile
175 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, 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 pr. 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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# 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:
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include include/config/auto.conf
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include scripts/Kbuild.include
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# for ld_flags
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include scripts/Makefile.lib
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mixed-build-prefix = $(if $(KBUILD_MIXED_TREE),$(KBUILD_MIXED_TREE)/)
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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_MODPOST_WARN),-w) \
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-o $@
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ifdef MODPOST_VMLINUX
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quiet_cmd_modpost = MODPOST $@
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cmd_modpost = $(MODPOST) $<
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vmlinux.symvers: vmlinux.o
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$(call cmd,modpost)
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__modpost: vmlinux.symvers
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else
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ifeq ($(KBUILD_EXTMOD),)
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input-symdump := $(mixed-build-prefix)vmlinux.symvers
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output-symdump := Module.symvers
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module_srcpath := $(srctree)
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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 $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
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$(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
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# modpost option for external modules
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MODPOST += -e
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input-symdump := Module.symvers $(KBUILD_EXTRA_SYMBOLS)
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output-symdump := $(KBUILD_EXTMOD)/Module.symvers
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# Get the external module's source path. KBUILD_EXTMOD could either be an
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# absolute path or relative path from $(srctree). This makes sure that we
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# aren't using a relative path from a separate working directory (O= or
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# KBUILD_OUTPUT) since that may not be the actual module's SCM project path. So
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# check the path relative to $(srctree) first.
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ifneq ($(realpath $(srctree)/$(KBUILD_EXTMOD) 2>/dev/null),)
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module_srcpath := $(srctree)/$(KBUILD_EXTMOD)
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else
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module_srcpath := $(KBUILD_EXTMOD)
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endif
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endif
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ifeq ($(CONFIG_MODULE_SCMVERSION),y)
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# Get the SCM version of the module. `sed` verifies setlocalversion returns
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# a proper revision based on the SCM type, e.g. git, mercurial, or svn.
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module_scmversion := $(shell $(srctree)/scripts/setlocalversion $(module_srcpath) | \
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sed -n 's/.*-\(\(g\|hg\)[a-fA-F0-9]\+\(-dirty\)\?\|svn[0-9]\+\).*/\1/p')
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ifneq ($(module_scmversion),)
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MODPOST += -v $(module_scmversion)
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endif
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endif
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# modpost options for modules (both in-kernel and external)
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MODPOST += \
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$(addprefix -i ,$(wildcard $(input-symdump))) \
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$(if $(KBUILD_NSDEPS),-d $(MODULES_NSDEPS)) \
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$(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N)
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# '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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# Clear VPATH to not search for *.symvers in $(srctree). Check only $(objtree).
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VPATH :=
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$(input-symdump):
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@echo >&2 'WARNING: Symbol version dump "$@" is missing.'
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@echo >&2 ' Modules may not have dependencies or modversions.'
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ifdef CONFIG_LTO_CLANG
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# With CONFIG_LTO_CLANG, .o files might be LLVM bitcode, so we need to run
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# LTO to compile them into native code before running modpost
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prelink-ext := .lto
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quiet_cmd_cc_lto_link_modules = LTO [M] $@
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cmd_cc_lto_link_modules = \
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$(LD) $(ld_flags) -r -o $@ \
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$(shell [ -s $(@:.lto.o=.o.symversions) ] && \
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echo -T $(@:.lto.o=.o.symversions)) \
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--whole-archive $^
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%.lto.o: %.o
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$(call if_changed,cc_lto_link_modules)
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endif
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modules := $(sort $(shell cat $(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 = sed 's/\.ko$$/$(prelink-ext)\.o/' $< | $(MODPOST) -T -
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$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(prelink-ext).o) FORCE
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$(call if_changed,modpost)
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targets += $(output-symdump)
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__modpost: $(output-symdump)
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ifneq ($(KBUILD_MODPOST_NOFINAL),1)
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$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modfinal
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endif
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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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endif
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.PHONY: $(PHONY)
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