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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 in the device kernel
should point to the generic kernel's vmlinux and the device
kernel should skip compilation of built-in files.
Change ee1b16e80d
adds support for KBUILD_MIXED_TREE
in Makefile and Makefile.modpost. This change adds support for
KBUILD_MIXED_TREE in Makefile.modfinal, where vmlinux is referenced.
Bug: 202075496
Change-Id: I9bb3ff34fd6b5f0510b87648b9942af25c903de0
Signed-off-by: Yifan Hong <elsk@google.com>
84 lines
2.9 KiB
Makefile
84 lines
2.9 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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# ===========================================================================
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# Module final link
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# ===========================================================================
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PHONY := __modfinal
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__modfinal:
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for c_flags and mod-prelink-ext
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include $(srctree)/scripts/Makefile.lib
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mixed-build-prefix = $(if $(KBUILD_MIXED_TREE),$(KBUILD_MIXED_TREE)/)
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# find all modules listed in modules.order
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modules := $(sort $(shell cat $(MODORDER)))
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__modfinal: $(modules)
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@:
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# modname and part-of-module are set to make c_flags define proper module flags
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modname = $(notdir $(@:.mod.o=))
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part-of-module = y
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quiet_cmd_cc_o_c = CC [M] $@
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cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI), $(c_flags)) -c -o $@ $<
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%.mod.o: %.mod.c FORCE
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$(call if_changed_dep,cc_o_c)
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ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
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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 $(KBUILD_LDFLAGS) \
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$(KBUILD_LDFLAGS_MODULE) $(LDFLAGS_MODULE) \
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-T scripts/module.lds -o $@ $(filter %.o, $^); \
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$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
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quiet_cmd_btf_ko = BTF [M] $@
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cmd_btf_ko = \
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if [ -f $(mixed-build-prefix)vmlinux ]; then \
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LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base $(mixed-build-prefix)vmlinux $@; \
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else \
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printf "Skipping BTF generation for %s due to unavailability of $(mixed-build-prefix)vmlinux\n" $@ 1>&2; \
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fi;
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# Same as newer-prereqs, but allows to exclude specified extra dependencies
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newer_prereqs_except = $(filter-out $(PHONY) $(1),$?)
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# Same as if_changed, but allows to exclude specified extra dependencies
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if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \
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$(cmd); \
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printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
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# Re-generate module BTFs if either module's .ko or vmlinux changed
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$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),$(mixed-build-prefix)vmlinux) FORCE
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+$(call if_changed_except,ld_ko_o,$(mixed-build-prefix)vmlinux)
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ifdef CONFIG_DEBUG_INFO_BTF_MODULES
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+$(if $(newer-prereqs),$(call cmd,btf_ko))
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endif
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targets += $(modules) $(modules:.ko=.mod.o)
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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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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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