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),) 55ifneq ($(filter %/,$(LLVM)),) 56LLVM_PREFIX := $(LLVM) 57else ifneq ($(filter -%,$(LLVM)),) 58LLVM_SUFFIX := $(LLVM) 59endif 60 61$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX)) 62$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)) 63$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)) 64$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX)) 65$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX)) 66else 67# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. 68$(call allow-override,CC,$(CROSS_COMPILE)gcc) 69$(call allow-override,AR,$(CROSS_COMPILE)ar) 70$(call allow-override,LD,$(CROSS_COMPILE)ld) 71$(call allow-override,CXX,$(CROSS_COMPILE)g++) 72$(call allow-override,STRIP,$(CROSS_COMPILE)strip) 73endif 74 75CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) 76 77ifneq ($(LLVM),) 78HOSTAR ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX) 79HOSTCC ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX) 80HOSTLD ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX) 81else 82HOSTAR ?= ar 83HOSTCC ?= gcc 84HOSTLD ?= ld 85endif 86 87# Some tools require Clang, LLC and/or LLVM utils 88CLANG ?= clang 89LLC ?= llc 90LLVM_CONFIG ?= llvm-config 91LLVM_OBJCOPY ?= llvm-objcopy 92LLVM_STRIP ?= llvm-strip 93 94# Some tools require bpftool 95SYSTEM_BPFTOOL ?= bpftool 96 97ifeq ($(CC_NO_CLANG), 1) 98EXTRA_WARNINGS += -Wstrict-aliasing=3 99 100else ifneq ($(CROSS_COMPILE),) 101# Allow userspace to override CLANG_CROSS_FLAGS to specify their own 102# sysroots and flags or to avoid the GCC call in pure Clang builds. 103ifeq ($(CLANG_CROSS_FLAGS),) 104CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) 105GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) 106ifneq ($(GCC_TOOLCHAIN_DIR),) 107CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) 108CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) 109CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) 110endif # GCC_TOOLCHAIN_DIR 111endif # CLANG_CROSS_FLAGS 112CFLAGS += $(CLANG_CROSS_FLAGS) 113AFLAGS += $(CLANG_CROSS_FLAGS) 114else 115CLANG_CROSS_FLAGS := 116endif # CROSS_COMPILE 117 118# Hack to avoid type-punned warnings on old systems such as RHEL5: 119# We should be changing CFLAGS and checking gcc version, but this 120# will do for now and keep the above -Wstrict-aliasing=3 in place 121# in newer systems. 122# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 123# 124# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ 125# and https://gcc.gnu.org/gcc-4.8/changes.html, 126# that takes into account Linus's comments (search for Wshadow) for the reasoning about 127# -Wshadow not being interesting before gcc 4.8. 128 129ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 130EXTRA_WARNINGS += -fno-strict-aliasing 131EXTRA_WARNINGS += -Wno-shadow 132else 133EXTRA_WARNINGS += -Wshadow 134endif 135 136ifneq ($(findstring $(MAKEFLAGS), w),w) 137PRINT_DIR = --no-print-directory 138else 139NO_SUBDIR = : 140endif 141 142# Beautify output 143# --------------------------------------------------------------------------- 144# 145# Most of build commands in Kbuild start with "cmd_". You can optionally define 146# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from 147# that command is printed by default. 148# 149# e.g.) 150# quiet_cmd_depmod = DEPMOD $(MODLIB) 151# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE) 152# 153# A simple variant is to prefix commands with $(Q) - that's useful 154# for commands that shall be hidden in non-verbose mode. 155# 156# $(Q)$(MAKE) $(build)=scripts/basic 157# 158# To put more focus on warnings, be less verbose as default 159# Use 'make V=1' to see the full commands 160 161ifeq ($(V),1) 162 quiet = 163 Q = 164else 165 quiet = quiet_ 166 Q = @ 167endif 168 169# If the user is running make -s (silent mode), suppress echoing of commands 170# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS. 171ifeq ($(filter 3.%,$(MAKE_VERSION)),) 172short-opts := $(firstword -$(MAKEFLAGS)) 173else 174short-opts := $(filter-out --%,$(MAKEFLAGS)) 175endif 176 177ifneq ($(findstring s,$(short-opts)),) 178 silent=1 179 quiet=silent_ 180endif 181 182export quiet Q 183 184# 185# Define a callable command for descending to a new directory 186# 187# Call by doing: $(call descend,directory[,target]) 188# 189descend = \ 190 +mkdir -p $(OUTPUT)$(1) && \ 191 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 192 193QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 194QUIET_SUBDIR1 = 195 196ifneq ($(silent),1) 197 ifneq ($(V),1) 198 QUIET_CC = @echo ' CC '$@; 199 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 200 QUIET_CLANG = @echo ' CLANG '$@; 201 QUIET_AR = @echo ' AR '$@; 202 QUIET_LINK = @echo ' LINK '$@; 203 QUIET_MKDIR = @echo ' MKDIR '$@; 204 QUIET_GEN = @echo ' GEN '$@; 205 QUIET_SUBDIR0 = +@subdir= 206 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 207 echo ' SUBDIR '$$subdir; \ 208 $(MAKE) $(PRINT_DIR) -C $$subdir 209 QUIET_FLEX = @echo ' FLEX '$@; 210 QUIET_BISON = @echo ' BISON '$@; 211 QUIET_GENSKEL = @echo ' GENSKEL '$@; 212 213 descend = \ 214 +@echo ' DESCEND '$(1); \ 215 mkdir -p $(OUTPUT)$(1) && \ 216 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 217 218 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 219 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 220 QUIET_UNINST = @printf ' UNINST %s\n' $1; 221 endif 222endif 223 224pound := \# 225