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 90endif 91 92# Hack to avoid type-punned warnings on old systems such as RHEL5: 93# We should be changing CFLAGS and checking gcc version, but this 94# will do for now and keep the above -Wstrict-aliasing=3 in place 95# in newer systems. 96# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 97# 98# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/ 99# and https://gcc.gnu.org/gcc-4.8/changes.html, 100# that takes into account Linus's comments (search for Wshadow) for the reasoning about 101# -Wshadow not being interesting before gcc 4.8. 102 103ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 104EXTRA_WARNINGS += -fno-strict-aliasing 105EXTRA_WARNINGS += -Wno-shadow 106else 107EXTRA_WARNINGS += -Wshadow 108endif 109 110ifneq ($(findstring $(MAKEFLAGS), w),w) 111PRINT_DIR = --no-print-directory 112else 113NO_SUBDIR = : 114endif 115 116ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),) 117 silent=1 118endif 119 120# 121# Define a callable command for descending to a new directory 122# 123# Call by doing: $(call descend,directory[,target]) 124# 125descend = \ 126 +mkdir -p $(OUTPUT)$(1) && \ 127 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 128 129QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 130QUIET_SUBDIR1 = 131 132ifneq ($(silent),1) 133 ifneq ($(V),1) 134 QUIET_CC = @echo ' CC '$@; 135 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 136 QUIET_CLANG = @echo ' CLANG '$@; 137 QUIET_AR = @echo ' AR '$@; 138 QUIET_LINK = @echo ' LINK '$@; 139 QUIET_MKDIR = @echo ' MKDIR '$@; 140 QUIET_GEN = @echo ' GEN '$@; 141 QUIET_SUBDIR0 = +@subdir= 142 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 143 echo ' SUBDIR '$$subdir; \ 144 $(MAKE) $(PRINT_DIR) -C $$subdir 145 QUIET_FLEX = @echo ' FLEX '$@; 146 QUIET_BISON = @echo ' BISON '$@; 147 QUIET_GENSKEL = @echo ' GENSKEL '$@; 148 149 descend = \ 150 +@echo ' DESCEND '$(1); \ 151 mkdir -p $(OUTPUT)$(1) && \ 152 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 153 154 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 155 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 156 QUIET_UNINST = @printf ' UNINST %s\n' $1; 157 endif 158endif 159 160pound := \# 161