1# SPDX-License-Identifier: GPL-2.0 2ifneq ($(O),) 3ifeq ($(origin O), command line) 4 $(if $(shell cd $(PWD); test -d $(O) || echo $(O)),$(error O=$(O) does not exist),) 5 ABSOLUTE_O := $(shell cd $(PWD); cd $(O) ; pwd) 6 OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/) 7 COMMAND_O := O=$(ABSOLUTE_O) 8ifeq ($(objtree),) 9 objtree := $(O) 10endif 11endif 12endif 13 14# check that the output directory actually exists 15ifneq ($(OUTPUT),) 16OUTDIR := $(shell cd $(OUTPUT) && pwd) 17$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist)) 18endif 19 20# 21# Include saner warnings here, which can catch bugs: 22# 23EXTRA_WARNINGS := -Wbad-function-cast 24EXTRA_WARNINGS += -Wdeclaration-after-statement 25EXTRA_WARNINGS += -Wformat-security 26EXTRA_WARNINGS += -Wformat-y2k 27EXTRA_WARNINGS += -Winit-self 28EXTRA_WARNINGS += -Wmissing-declarations 29EXTRA_WARNINGS += -Wmissing-prototypes 30EXTRA_WARNINGS += -Wnested-externs 31EXTRA_WARNINGS += -Wno-system-headers 32EXTRA_WARNINGS += -Wold-style-definition 33EXTRA_WARNINGS += -Wpacked 34EXTRA_WARNINGS += -Wredundant-decls 35EXTRA_WARNINGS += -Wstrict-prototypes 36EXTRA_WARNINGS += -Wswitch-default 37EXTRA_WARNINGS += -Wswitch-enum 38EXTRA_WARNINGS += -Wundef 39EXTRA_WARNINGS += -Wwrite-strings 40EXTRA_WARNINGS += -Wformat 41EXTRA_WARNINGS += -Wno-type-limits 42 43# Makefiles suck: This macro sets a default value of $(2) for the 44# variable named by $(1), unless the variable has been set by 45# environment or command line. This is necessary for CC and AR 46# because make sets default values, so the simpler ?= approach 47# won't work as expected. 48define allow-override 49 $(if $(or $(findstring environment,$(origin $(1))),\ 50 $(findstring command line,$(origin $(1)))),,\ 51 $(eval $(1) = $(2))) 52endef 53 54ifneq ($(LLVM),) 55 ifneq ($(filter %/,$(LLVM)),) 56 LLVM_PREFIX := $(LLVM) 57 else ifneq ($(filter -%,$(LLVM)),) 58 LLVM_SUFFIX := $(LLVM) 59 else ifneq ($(LLVM),1) 60 $(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst) 61 endif 62 63 $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) 64 $(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) 65 $(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) 66 $(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)) 67 $(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)) 68 $(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)) 69 $(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)) 70 $(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX)) 71 $(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)) 72 $(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)) 73 $(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX)) 74 $(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX)) 75 $(call allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX)) 76 $(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX)) 77 $(call allow-override,HOSTREADELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX)) 78else 79 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. 80 $(call allow-override,CC,$(CROSS_COMPILE)gcc) 81 $(call allow-override,AR,$(CROSS_COMPILE)ar) 82 $(call allow-override,LD,$(CROSS_COMPILE)ld) 83 $(call allow-override,CXX,$(CROSS_COMPILE)g++) 84 $(call allow-override,STRIP,$(CROSS_COMPILE)strip) 85 $(call allow-override,READELF,$(CROSS_COMPILE)readelf) 86 87 # Host versions aren't prefixed 88 $(call allow-override,HOSTAR,ar) 89 $(call allow-override,HOSTCC,gcc) 90 $(call allow-override,HOSTLD,ld) 91 $(call allow-override,HOSTREADELF,readelf) 92 93 # Some tools still require Clang, LLC and/or LLVM utils 94 $(call allow-override,CLANG,clang) 95 $(call allow-override,LLC,llc) 96 $(call allow-override,LLVM_CONFIG,llvm-config) 97 $(call allow-override,LLVM_OBJCOPY,llvm-objcopy) 98 $(call allow-override,LLVM_STRIP,llvm-strip) 99endif 100 101CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) 102 103# Some tools require bpftool 104SYSTEM_BPFTOOL ?= bpftool 105 106RUSTC ?= rustc 107 108ifeq ($(CC_NO_CLANG), 1) 109EXTRA_WARNINGS += -Wstrict-aliasing=3 110 111else ifneq ($(CROSS_COMPILE),) 112# Allow userspace to override CLANG_CROSS_FLAGS to specify their own 113# sysroots and flags or to avoid the GCC call in pure Clang builds. 114ifeq ($(CLANG_CROSS_FLAGS),) 115CLANG_TARGET := $(notdir $(CROSS_COMPILE:%-=%)) 116CLANG_TARGET := $(subst s390-linux,s390x-linux,$(CLANG_TARGET)) 117CLANG_CROSS_FLAGS := --target=$(CLANG_TARGET) 118GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) 119ifneq ($(GCC_TOOLCHAIN_DIR),) 120CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) 121CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) 122CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) 123endif # GCC_TOOLCHAIN_DIR 124endif # CLANG_CROSS_FLAGS 125CFLAGS += $(CLANG_CROSS_FLAGS) 126AFLAGS += $(CLANG_CROSS_FLAGS) 127else 128CLANG_CROSS_FLAGS := 129endif # CROSS_COMPILE 130 131# Hack to avoid type-punned warnings on old systems such as RHEL5: 132# We should be changing CFLAGS and checking gcc version, but this 133# will do for now and keep the above -Wstrict-aliasing=3 in place 134# in newer systems. 135# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 136# 137# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ 138# and https://gcc.gnu.org/gcc-4.8/changes.html, 139# that takes into account Linus's comments (search for Wshadow) for the reasoning about 140# -Wshadow not being interesting before gcc 4.8. 141 142ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 143EXTRA_WARNINGS += -fno-strict-aliasing 144EXTRA_WARNINGS += -Wno-shadow 145else 146EXTRA_WARNINGS += -Wshadow 147endif 148 149ifneq ($(findstring $(MAKEFLAGS), w),w) 150PRINT_DIR = --no-print-directory 151else 152NO_SUBDIR = : 153endif 154 155# Beautify output 156# --------------------------------------------------------------------------- 157# 158# Most of build commands in Kbuild start with "cmd_". You can optionally define 159# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from 160# that command is printed by default. 161# 162# e.g.) 163# quiet_cmd_depmod = DEPMOD $(MODLIB) 164# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE) 165# 166# A simple variant is to prefix commands with $(Q) - that's useful 167# for commands that shall be hidden in non-verbose mode. 168# 169# $(Q)$(MAKE) $(build)=scripts/basic 170# 171# To put more focus on warnings, be less verbose as default 172# Use 'make V=1' to see the full commands 173 174ifeq ($(V),1) 175 quiet = 176 Q = 177else 178 quiet = quiet_ 179 Q = @ 180endif 181 182# If the user is running make -s (silent mode), suppress echoing of commands 183# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS. 184ifeq ($(filter 3.%,$(MAKE_VERSION)),) 185short-opts := $(firstword -$(MAKEFLAGS)) 186else 187short-opts := $(filter-out --%,$(MAKEFLAGS)) 188endif 189 190ifneq ($(findstring s,$(short-opts)),) 191 silent=1 192 quiet=silent_ 193endif 194 195export quiet Q 196 197# 198# Define a callable command for descending to a new directory 199# 200# Call by doing: $(call descend,directory[,target]) 201# 202descend = \ 203 +mkdir -p $(OUTPUT)$(1) && \ 204 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 205 206QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 207QUIET_SUBDIR1 = 208 209ifneq ($(silent),1) 210 ifneq ($(V),1) 211 QUIET_CC = @echo ' CC '$@; 212 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 213 QUIET_CLANG = @echo ' CLANG '$@; 214 QUIET_AR = @echo ' AR '$@; 215 QUIET_LINK = @echo ' LINK '$@; 216 QUIET_MKDIR = @echo ' MKDIR '$@; 217 QUIET_GEN = @echo ' GEN '$@; 218 QUIET_SUBDIR0 = +@subdir= 219 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 220 echo ' SUBDIR '$$subdir; \ 221 $(MAKE) $(PRINT_DIR) -C $$subdir 222 QUIET_FLEX = @echo ' FLEX '$@; 223 QUIET_BISON = @echo ' BISON '$@; 224 QUIET_GENSKEL = @echo ' GENSKEL '$@; 225 226 descend = \ 227 +@echo ' DESCEND '$(1); \ 228 mkdir -p $(OUTPUT)$(1) && \ 229 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 230 231 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 232 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 233 QUIET_UNINST = @printf ' UNINST %s\n' $1; 234 endif 235endif 236 237pound := \# 238