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654102df2a
Some architectures embed boot DTBs in vmlinux. A potential issue for these architectures is a race condition during parallel builds because Kbuild descends into arch/*/boot/dts/ twice. One build thread is initiated by the 'dtbs' target, which is a prerequisite of the 'all' target in the top-level Makefile: ifdef CONFIG_OF_EARLY_FLATTREE all: dtbs endif For architectures that support the built-in boot dtb, arch/*/boot/dts/ is visited also during the ordinary directory traversal in order to build obj-y objects that wrap DTBs. Since these build threads are unaware of each other, they can run simultaneously during parallel builds. This commit introduces a generic build rule to scripts/Makefile.vmlinux to support embedded boot DTBs in a race-free way. Architectures that want to use this rule need to select CONFIG_GENERIC_BUILTIN_DTB. After the migration, Makefiles under arch/*/boot/dts/ will be visited only once to build only *.dtb files. This change also aims to unify the CONFIG options used for built-in DTBs support. Currently, different architectures use different CONFIG options for the same purposes. With this commit, the CONFIG options will be unified as follows: - CONFIG_GENERIC_BUILTIN_DTB This enables the generic rule for built-in boot DTBs. This will be renamed to CONFIG_BUILTIN_DTB after all architectures migrate to the generic rule. - CONFIG_BUILTIN_DTB_NAME This specifies the path to the embedded DTB. (relative to arch/*/boot/dts/) - CONFIG_BUILTIN_DTB_ALL If this is enabled, all DTB files compiled under arch/*/boot/dts/ are embedded into vmlinux. Only used by MIPS. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
114 lines
3.2 KiB
Makefile
114 lines
3.2 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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PHONY := __default
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__default: vmlinux
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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
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include $(srctree)/scripts/Makefile.lib
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targets :=
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quiet_cmd_cc_o_c = CC $@
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cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
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%.o: %.c FORCE
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$(call if_changed_dep,cc_o_c)
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quiet_cmd_as_o_S = AS $@
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cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
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%.o: %.S FORCE
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$(call if_changed_dep,as_o_S)
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# Built-in dtb
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# ---------------------------------------------------------------------------
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quiet_cmd_wrap_dtbs = WRAP $@
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cmd_wrap_dtbs = { \
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echo '\#include <asm-generic/vmlinux.lds.h>'; \
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echo '.section .dtb.init.rodata,"a"'; \
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while read dtb; do \
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symbase=__dtb_$$(basename -s .dtb "$${dtb}" | tr - _); \
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echo '.balign STRUCT_ALIGNMENT'; \
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echo ".global $${symbase}_begin"; \
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echo "$${symbase}_begin:"; \
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echo '.incbin "'$$dtb'" '; \
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echo ".global $${symbase}_end"; \
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echo "$${symbase}_end:"; \
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done < $<; \
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} > $@
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.builtin-dtbs.S: .builtin-dtbs-list FORCE
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$(call if_changed,wrap_dtbs)
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quiet_cmd_gen_dtbs_list = GEN $@
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cmd_gen_dtbs_list = \
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$(if $(CONFIG_BUILTIN_DTB_NAME), echo "arch/$(SRCARCH)/boot/dts/$(CONFIG_BUILTIN_DTB_NAME).dtb",:) > $@
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.builtin-dtbs-list: arch/$(SRCARCH)/boot/dts/dtbs-list FORCE
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$(call if_changed,$(if $(CONFIG_BUILTIN_DTB_ALL),copy,gen_dtbs_list))
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targets += .builtin-dtbs-list
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ifdef CONFIG_GENERIC_BUILTIN_DTB
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targets += .builtin-dtbs.S .builtin-dtbs.o
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vmlinux: .builtin-dtbs.o
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endif
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# vmlinux
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# ---------------------------------------------------------------------------
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ifdef CONFIG_MODULES
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targets += .vmlinux.export.o
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vmlinux: .vmlinux.export.o
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endif
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ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
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# Final link of vmlinux with optional arch pass after final link
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cmd_link_vmlinux = \
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$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
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$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
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targets += vmlinux
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vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
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+$(call if_changed_dep,link_vmlinux)
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# module.builtin.ranges
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# ---------------------------------------------------------------------------
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ifdef CONFIG_BUILTIN_MODULE_RANGES
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__default: modules.builtin.ranges
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quiet_cmd_modules_builtin_ranges = GEN $@
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cmd_modules_builtin_ranges = gawk -f $(real-prereqs) > $@
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targets += modules.builtin.ranges
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modules.builtin.ranges: $(srctree)/scripts/generate_builtin_ranges.awk \
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modules.builtin vmlinux.map vmlinux.o.map FORCE
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$(call if_changed,modules_builtin_ranges)
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vmlinux.map: vmlinux
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@:
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endif
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# Add FORCE to the prerequisites 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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