1# SPDX-License-Identifier: GPL-2.0 2ifneq ($(O),) 3ifeq ($(origin O), command line) 4 dummy := $(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$(call allow-override,CC,clang) 56$(call allow-override,AR,llvm-ar) 57$(call allow-override,LD,ld.lld) 58$(call allow-override,CXX,clang++) 59$(call allow-override,STRIP,llvm-strip) 60else 61# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. 62$(call allow-override,CC,$(CROSS_COMPILE)gcc) 63$(call allow-override,AR,$(CROSS_COMPILE)ar) 64$(call allow-override,LD,$(CROSS_COMPILE)ld) 65$(call allow-override,CXX,$(CROSS_COMPILE)g++) 66$(call allow-override,STRIP,$(CROSS_COMPILE)strip) 67endif 68 69CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) 70 71ifneq ($(LLVM),) 72HOSTAR ?= llvm-ar 73HOSTCC ?= clang 74HOSTLD ?= ld.lld 75else 76HOSTAR ?= ar 77HOSTCC ?= gcc 78HOSTLD ?= ld 79endif 80 81# Some tools require Clang, LLC and/or LLVM utils 82CLANG ?= clang 83LLC ?= llc 84LLVM_CONFIG ?= llvm-config 85LLVM_OBJCOPY ?= llvm-objcopy 86LLVM_STRIP ?= llvm-strip 87 88ifeq ($(CC_NO_CLANG), 1) 89EXTRA_WARNINGS += -Wstrict-aliasing=3 90 91else ifneq ($(CROSS_COMPILE),) 92# Allow userspace to override CLANG_CROSS_FLAGS to specify their own 93# sysroots and flags or to avoid the GCC call in pure Clang builds. 94ifeq ($(CLANG_CROSS_FLAGS),) 95CLANG_CROSS_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) 96GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null)) 97ifneq ($(GCC_TOOLCHAIN_DIR),) 98CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) 99CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot) 100CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..) 101endif # GCC_TOOLCHAIN_DIR 102endif # CLANG_CROSS_FLAGS 103CFLAGS += $(CLANG_CROSS_FLAGS) 104AFLAGS += $(CLANG_CROSS_FLAGS) 105endif # CROSS_COMPILE 106 107# Hack to avoid type-punned warnings on old systems such as RHEL5: 108# We should be changing CFLAGS and checking gcc version, but this 109# will do for now and keep the above -Wstrict-aliasing=3 in place 110# in newer systems. 111# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 112# 113# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ 114# and https://gcc.gnu.org/gcc-4.8/changes.html, 115# that takes into account Linus's comments (search for Wshadow) for the reasoning about 116# -Wshadow not being interesting before gcc 4.8. 117 118ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 119EXTRA_WARNINGS += -fno-strict-aliasing 120EXTRA_WARNINGS += -Wno-shadow 121else 122EXTRA_WARNINGS += -Wshadow 123endif 124 125ifneq ($(findstring $(MAKEFLAGS), w),w) 126PRINT_DIR = --no-print-directory 127else 128NO_SUBDIR = : 129endif 130 131ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),) 132 silent=1 133endif 134 135# 136# Define a callable command for descending to a new directory 137# 138# Call by doing: $(call descend,directory[,target]) 139# 140descend = \ 141 +mkdir -p $(OUTPUT)$(1) && \ 142 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 143 144QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 145QUIET_SUBDIR1 = 146 147ifneq ($(silent),1) 148 ifneq ($(V),1) 149 QUIET_CC = @echo ' CC '$@; 150 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 151 QUIET_CLANG = @echo ' CLANG '$@; 152 QUIET_AR = @echo ' AR '$@; 153 QUIET_LINK = @echo ' LINK '$@; 154 QUIET_MKDIR = @echo ' MKDIR '$@; 155 QUIET_GEN = @echo ' GEN '$@; 156 QUIET_SUBDIR0 = +@subdir= 157 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 158 echo ' SUBDIR '$$subdir; \ 159 $(MAKE) $(PRINT_DIR) -C $$subdir 160 QUIET_FLEX = @echo ' FLEX '$@; 161 QUIET_BISON = @echo ' BISON '$@; 162 QUIET_GENSKEL = @echo ' GENSKEL '$@; 163 164 descend = \ 165 +@echo ' DESCEND '$(1); \ 166 mkdir -p $(OUTPUT)$(1) && \ 167 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 168 169 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 170 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 171 QUIET_UNINST = @printf ' UNINST %s\n' $1; 172 endif 173endif 174 175pound := \# 176