16192a771d
More and more projects use libbpf and one day it'll likely be packaged and distributed as DSO and that requires ABI versioning so that both compatible and incompatible changes to ABI can be introduced in a safe way in the future without breaking executables dynamically linked with a previous version of the library. Usual way to do ABI versioning is version script for the linker. Add such a script for libbpf. All global symbols currently exported via LIBBPF_API macro are added to the version script libbpf.map. The version name LIBBPF_0.0.1 is constructed from the name of the library + version specified by $(LIBBPF_VERSION) in Makefile. Version script does not duplicate the work done by LIBBPF_API macro, it rather complements it. The macro is used at compile time and can be used by compiler to do optimization that can't be done at link time, it is purely about global symbol visibility. The version script, in turn, is used at link time and takes care of ABI versioning. Both techniques are described in details in [1]. Whenever ABI is changed in the future, version script should be changed appropriately. [1] https://www.akkadia.org/drepper/dsohowto.pdf Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
233 lines
6.6 KiB
Makefile
233 lines
6.6 KiB
Makefile
# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
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# Most of this file is copied from tools/lib/traceevent/Makefile
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BPF_VERSION = 0
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BPF_PATCHLEVEL = 0
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BPF_EXTRAVERSION = 1
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MAKEFLAGS += --no-print-directory
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ifeq ($(srctree),)
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srctree := $(patsubst %/,%,$(dir $(CURDIR)))
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srctree := $(patsubst %/,%,$(dir $(srctree)))
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srctree := $(patsubst %/,%,$(dir $(srctree)))
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#$(info Determined 'srctree' to be $(srctree))
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endif
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# Makefiles suck: This macro sets a default value of $(2) for the
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# variable named by $(1), unless the variable has been set by
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# environment or command line. This is necessary for CC and AR
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# because make sets default values, so the simpler ?= approach
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# won't work as expected.
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define allow-override
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$(if $(or $(findstring environment,$(origin $(1))),\
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$(findstring command line,$(origin $(1)))),,\
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$(eval $(1) = $(2)))
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endef
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# Allow setting CC and AR, or setting CROSS_COMPILE as a prefix.
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$(call allow-override,CC,$(CROSS_COMPILE)gcc)
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$(call allow-override,AR,$(CROSS_COMPILE)ar)
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INSTALL = install
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# Use DESTDIR for installing into a different root directory.
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# This is useful for building a package. The program will be
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# installed in this directory as if it was the root directory.
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# Then the build tool can move it later.
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DESTDIR ?=
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DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))'
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include $(srctree)/tools/scripts/Makefile.arch
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ifeq ($(LP64), 1)
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libdir_relative = lib64
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else
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libdir_relative = lib
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endif
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prefix ?= /usr/local
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libdir = $(prefix)/$(libdir_relative)
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man_dir = $(prefix)/share/man
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man_dir_SQ = '$(subst ','\'',$(man_dir))'
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export man_dir man_dir_SQ INSTALL
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export DESTDIR DESTDIR_SQ
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include ../../scripts/Makefile.include
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# copy a bit from Linux kbuild
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ifeq ("$(origin V)", "command line")
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VERBOSE = $(V)
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endif
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ifndef VERBOSE
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VERBOSE = 0
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endif
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FEATURE_USER = .libbpf
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FEATURE_TESTS = libelf libelf-mmap bpf reallocarray cxx
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FEATURE_DISPLAY = libelf bpf
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INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
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FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)
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check_feat := 1
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NON_CHECK_FEAT_TARGETS := clean TAGS tags cscope help
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ifdef MAKECMDGOALS
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ifeq ($(filter-out $(NON_CHECK_FEAT_TARGETS),$(MAKECMDGOALS)),)
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check_feat := 0
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endif
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endif
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ifeq ($(check_feat),1)
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ifeq ($(FEATURES_DUMP),)
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include $(srctree)/tools/build/Makefile.feature
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else
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include $(FEATURES_DUMP)
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endif
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endif
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export prefix libdir src obj
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# Shell quotes
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libdir_SQ = $(subst ','\'',$(libdir))
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libdir_relative_SQ = $(subst ','\'',$(libdir_relative))
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LIB_FILE = libbpf.a libbpf.so
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VERSION = $(BPF_VERSION)
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PATCHLEVEL = $(BPF_PATCHLEVEL)
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EXTRAVERSION = $(BPF_EXTRAVERSION)
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OBJ = $@
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N =
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LIBBPF_VERSION = $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)
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# Set compile option CFLAGS
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ifdef EXTRA_CFLAGS
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CFLAGS := $(EXTRA_CFLAGS)
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else
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CFLAGS := -g -Wall
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endif
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ifeq ($(feature-libelf-mmap), 1)
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override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
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endif
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ifeq ($(feature-reallocarray), 0)
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override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
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endif
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# Append required CFLAGS
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override CFLAGS += $(EXTRA_WARNINGS)
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override CFLAGS += -Werror -Wall
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override CFLAGS += -fPIC
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override CFLAGS += $(INCLUDES)
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override CFLAGS += -fvisibility=hidden
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ifeq ($(VERBOSE),1)
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Q =
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else
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Q = @
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endif
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# Disable command line variables (CFLAGS) override from top
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# level Makefile (perf), otherwise build Makefile will get
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# the same command line setup.
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MAKEOVERRIDES=
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all:
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export srctree OUTPUT CC LD CFLAGS V
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include $(srctree)/tools/build/Makefile.include
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BPF_IN := $(OUTPUT)libbpf-in.o
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LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))
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VERSION_SCRIPT := libbpf.map
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CMD_TARGETS = $(LIB_FILE)
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CXX_TEST_TARGET = $(OUTPUT)test_libbpf
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ifeq ($(feature-cxx), 1)
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CMD_TARGETS += $(CXX_TEST_TARGET)
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endif
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TARGETS = $(CMD_TARGETS)
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all: fixdep all_cmd
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all_cmd: $(CMD_TARGETS)
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$(BPF_IN): force elfdep bpfdep
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@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \
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(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \
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echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
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@(test -f ../../include/uapi/linux/bpf_common.h -a -f ../../../include/uapi/linux/bpf_common.h && ( \
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(diff -B ../../include/uapi/linux/bpf_common.h ../../../include/uapi/linux/bpf_common.h >/dev/null) || \
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echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf_common.h' differs from latest version at 'include/uapi/linux/bpf_common.h'" >&2 )) || true
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@(test -f ../../include/uapi/linux/netlink.h -a -f ../../../include/uapi/linux/netlink.h && ( \
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(diff -B ../../include/uapi/linux/netlink.h ../../../include/uapi/linux/netlink.h >/dev/null) || \
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echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/netlink.h' differs from latest version at 'include/uapi/linux/netlink.h'" >&2 )) || true
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@(test -f ../../include/uapi/linux/if_link.h -a -f ../../../include/uapi/linux/if_link.h && ( \
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(diff -B ../../include/uapi/linux/if_link.h ../../../include/uapi/linux/if_link.h >/dev/null) || \
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echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h'" >&2 )) || true
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$(Q)$(MAKE) $(build)=libbpf
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$(OUTPUT)libbpf.so: $(BPF_IN)
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$(QUIET_LINK)$(CC) --shared -Wl,--version-script=$(VERSION_SCRIPT) \
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$^ -o $@
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$(OUTPUT)libbpf.a: $(BPF_IN)
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$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
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$(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
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$(QUIET_LINK)$(CXX) $^ -lelf -o $@
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define do_install
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if [ ! -d '$(DESTDIR_SQ)$2' ]; then \
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$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2'; \
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fi; \
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$(INSTALL) $1 $(if $3,-m $3,) '$(DESTDIR_SQ)$2'
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endef
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install_lib: all_cmd
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$(call QUIET_INSTALL, $(LIB_FILE)) \
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$(call do_install,$(LIB_FILE),$(libdir_SQ))
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install_headers:
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$(call QUIET_INSTALL, headers) \
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$(call do_install,bpf.h,$(prefix)/include/bpf,644); \
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$(call do_install,libbpf.h,$(prefix)/include/bpf,644);
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$(call do_install,btf.h,$(prefix)/include/bpf,644);
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install: install_lib
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### Cleaning rules
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config-clean:
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$(call QUIET_CLEAN, config)
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$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null
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clean:
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$(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \
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*.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS
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$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf
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PHONY += force elfdep bpfdep
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force:
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elfdep:
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@if [ "$(feature-libelf)" != "1" ]; then echo "No libelf found"; exit 1 ; fi
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bpfdep:
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@if [ "$(feature-bpf)" != "1" ]; then echo "BPF API too old"; exit 1 ; fi
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# Declare the contents of the .PHONY variable as phony. We keep that
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# information in a variable so we can use it in if_changed and friends.
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.PHONY: $(PHONY)
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