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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-08-27 12:59:07 -04:00
380e3f23bb
Two parse-time probes still invoke $(CC) unconditionally:
- LP64 in tools/scripts/Makefile.arch, probing with
$(CC) -E -x c, pulled in twice by tools/perf/Makefile.perf;
- CC_NO_CLANG in tools/scripts/Makefile.include, probing with
$(CC) -dM -E -x c /dev/null.
In the corner case where gcc is not yet installed, the very setup the
install-build-deps target, added in the next patch of this series, is
meant for, these probes make even targets that never compile parse-time
spew errors like:
/bin/sh: 1: gcc: not found
/bin/sh: 1: gcc: not found
/bin/sh: 1: gcc: not found
Guard both probes with 'command -v' using the first word of CC so a
missing compiler is handled silently with the same result as a failing
probe (CC_NO_CLANG and LP64 unset/0), and with no behavior change when
the compiler is installed.
Only the first word is consulted because CC may carry arguments such as
'ccache gcc', and shell implementations differ in how 'command -v'
handles multiple words (dash only checks the first, bash any of them),
so validating the whole CC value would silently disable both probes on
some make SHELLs.
Assisted-by: opencode:deepseek-v4-flash-free
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
244 lines
8.4 KiB
Makefile
244 lines
8.4 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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ifneq ($(O),)
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ifeq ($(origin O), command line)
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$(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
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ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd)
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OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
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COMMAND_O := O=$(ABSOLUTE_O)
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ifeq ($(objtree),)
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objtree := $(O)
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endif
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endif
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endif
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# check that the output directory actually exists
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ifneq ($(OUTPUT),)
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OUTDIR := $(shell cd $(OUTPUT) && pwd)
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$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
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endif
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#
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# Include saner warnings here, which can catch bugs:
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#
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EXTRA_WARNINGS := -Wbad-function-cast
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EXTRA_WARNINGS += -Wdeclaration-after-statement
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EXTRA_WARNINGS += -Wformat-security
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EXTRA_WARNINGS += -Wformat-y2k
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EXTRA_WARNINGS += -Winit-self
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EXTRA_WARNINGS += -Wmissing-declarations
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EXTRA_WARNINGS += -Wmissing-prototypes
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EXTRA_WARNINGS += -Wnested-externs
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EXTRA_WARNINGS += -Wno-system-headers
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EXTRA_WARNINGS += -Wold-style-definition
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EXTRA_WARNINGS += -Wpacked
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EXTRA_WARNINGS += -Wredundant-decls
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EXTRA_WARNINGS += -Wstrict-prototypes
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EXTRA_WARNINGS += -Wswitch-default
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EXTRA_WARNINGS += -Wswitch-enum
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EXTRA_WARNINGS += -Wundef
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EXTRA_WARNINGS += -Wwrite-strings
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EXTRA_WARNINGS += -Wformat
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EXTRA_WARNINGS += -Wno-type-limits
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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) = $(2)))
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endef
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ifneq ($(LLVM),)
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ifneq ($(filter %/,$(LLVM)),)
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LLVM_PREFIX := $(LLVM)
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else ifneq ($(filter -%,$(LLVM)),)
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LLVM_SUFFIX := $(LLVM)
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else ifneq ($(LLVM),1)
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$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
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endif
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$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
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$(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
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$(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
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$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
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$(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
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$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
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$(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
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$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
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$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
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$(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
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$(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX))
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$(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX))
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$(call allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX))
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$(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
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$(call allow-override,HOSTREADELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
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else
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# Allow setting various cross-compile vars 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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$(call allow-override,LD,$(CROSS_COMPILE)ld)
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$(call allow-override,CXX,$(CROSS_COMPILE)g++)
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$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
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$(call allow-override,READELF,$(CROSS_COMPILE)readelf)
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# Host versions aren't prefixed
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$(call allow-override,HOSTAR,ar)
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$(call allow-override,HOSTCC,gcc)
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$(call allow-override,HOSTLD,ld)
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$(call allow-override,HOSTREADELF,readelf)
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# Some tools still require Clang, LLC and/or LLVM utils
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$(call allow-override,CLANG,clang)
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$(call allow-override,LLC,llc)
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$(call allow-override,LLVM_CONFIG,llvm-config)
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$(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
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$(call allow-override,LLVM_STRIP,llvm-strip)
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endif
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# The CC_NO_CLANG probe also runs at parse time for targets that never
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# compile, so guard it with 'command -v': when the compiler is not yet
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# installed, e.g. the first install-build-deps run, it would otherwise
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# spew "gcc: not found". Only the first word of CC is consulted, as CC
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# may carry arguments, e.g. 'ccache gcc'. A missing compiler leaves
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# CC_NO_CLANG at 1, as if the probe had failed.
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CC_NO_CLANG := $(shell if command -v $(firstword $(CC)) >/dev/null 2>&1; then $(CC) -dM -E -x c /dev/null; fi | grep -Fq "__clang__"; echo $$?)
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# Some tools require bpftool
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SYSTEM_BPFTOOL ?= bpftool
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RUSTC ?= rustc
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ifeq ($(CC_NO_CLANG), 1)
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EXTRA_WARNINGS += -Wstrict-aliasing=3
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else ifneq ($(CROSS_COMPILE),)
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# Allow userspace to override CLANG_CROSS_FLAGS to specify their own
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# sysroots and flags or to avoid the GCC call in pure Clang builds.
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ifeq ($(CLANG_CROSS_FLAGS),)
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CLANG_TARGET := $(notdir $(CROSS_COMPILE:%-=%))
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CLANG_TARGET := $(subst s390-linux,s390x-linux,$(CLANG_TARGET))
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CLANG_CROSS_FLAGS := --target=$(CLANG_TARGET)
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GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null))
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ifneq ($(GCC_TOOLCHAIN_DIR),)
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CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
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CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot)
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CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..)
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endif # GCC_TOOLCHAIN_DIR
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endif # CLANG_CROSS_FLAGS
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CFLAGS += $(CLANG_CROSS_FLAGS)
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AFLAGS += $(CLANG_CROSS_FLAGS)
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else
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CLANG_CROSS_FLAGS :=
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endif # CROSS_COMPILE
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# Hack to avoid type-punned warnings on old systems such as RHEL5:
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# We should be changing CFLAGS and checking gcc version, but this
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# will do for now and keep the above -Wstrict-aliasing=3 in place
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# in newer systems.
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# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
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#
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# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/
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# and https://gcc.gnu.org/gcc-4.8/changes.html,
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# that takes into account Linus's comments (search for Wshadow) for the reasoning about
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# -Wshadow not being interesting before gcc 4.8.
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ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
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EXTRA_WARNINGS += -fno-strict-aliasing
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EXTRA_WARNINGS += -Wno-shadow
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else
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EXTRA_WARNINGS += -Wshadow
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endif
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ifneq ($(findstring $(MAKEFLAGS), w),w)
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PRINT_DIR = --no-print-directory
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else
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NO_SUBDIR = :
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endif
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# Beautify output
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# ---------------------------------------------------------------------------
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#
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# Most of build commands in Kbuild start with "cmd_". You can optionally define
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# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
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# that command is printed by default.
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#
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# e.g.)
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# quiet_cmd_depmod = DEPMOD $(MODLIB)
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# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
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#
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# A simple variant is to prefix commands with $(Q) - that's useful
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# for commands that shall be hidden in non-verbose mode.
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#
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# $(Q)$(MAKE) $(build)=scripts/basic
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#
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# To put more focus on warnings, be less verbose as default
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# Use 'make V=1' to see the full commands
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ifeq ($(V),1)
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quiet =
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Q =
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else
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quiet = quiet_
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Q = @
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endif
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# If the user is running make -s (silent mode), suppress echoing of commands
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# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
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ifeq ($(filter 3.%,$(MAKE_VERSION)),)
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short-opts := $(firstword -$(MAKEFLAGS))
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else
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short-opts := $(filter-out --%,$(MAKEFLAGS))
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endif
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ifneq ($(findstring s,$(short-opts)),)
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silent=1
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quiet=silent_
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endif
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export quiet Q
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#
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# Define a callable command for descending to a new directory
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#
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# Call by doing: $(call descend,directory[,target])
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#
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descend = \
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+mkdir -p $(OUTPUT)$(1) && \
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$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
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QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
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QUIET_SUBDIR1 =
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ifneq ($(silent),1)
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ifneq ($(V),1)
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QUIET_CC = @echo ' CC '$@;
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QUIET_CC_FPIC = @echo ' CC FPIC '$@;
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QUIET_CLANG = @echo ' CLANG '$@;
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QUIET_AR = @echo ' AR '$@;
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QUIET_LINK = @echo ' LINK '$@;
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QUIET_MKDIR = @echo ' MKDIR '$@;
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QUIET_GEN = @echo ' GEN '$@;
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QUIET_SUBDIR0 = +@subdir=
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QUIET_SUBDIR1 = ;$(NO_SUBDIR) \
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echo ' SUBDIR '$$subdir; \
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$(MAKE) $(PRINT_DIR) -C $$subdir
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QUIET_FLEX = @echo ' FLEX '$@;
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QUIET_BISON = @echo ' BISON '$@;
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QUIET_GENSKEL = @echo ' GENSKEL '$@;
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descend = \
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+@echo ' DESCEND '$(1); \
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mkdir -p $(OUTPUT)$(1) && \
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$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
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QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
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QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
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QUIET_UNINST = @printf ' UNINST %s\n' $1;
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endif
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endif
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pound := \#
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