1# SPDX-License-Identifier: GPL-2.0 2ifneq ($(O),) 3ifeq ($(origin O), command line) 4 dummy := $(if $(shell test -d $(O) || echo $(O)),$(error O=$(O) does not exist),) 5 ABSOLUTE_O := $(shell 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 41 42CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?) 43 44# Makefiles suck: This macro sets a default value of $(2) for the 45# variable named by $(1), unless the variable has been set by 46# environment or command line. This is necessary for CC and AR 47# because make sets default values, so the simpler ?= approach 48# won't work as expected. 49define allow-override 50 $(if $(or $(findstring environment,$(origin $(1))),\ 51 $(findstring command line,$(origin $(1)))),,\ 52 $(eval $(1) = $(2))) 53endef 54 55# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix. 56$(call allow-override,CC,$(CROSS_COMPILE)gcc) 57$(call allow-override,AR,$(CROSS_COMPILE)ar) 58$(call allow-override,LD,$(CROSS_COMPILE)ld) 59$(call allow-override,CXX,$(CROSS_COMPILE)g++) 60$(call allow-override,STRIP,$(CROSS_COMPILE)strip) 61 62ifeq ($(CC_NO_CLANG), 1) 63EXTRA_WARNINGS += -Wstrict-aliasing=3 64endif 65 66# Hack to avoid type-punned warnings on old systems such as RHEL5: 67# We should be changing CFLAGS and checking gcc version, but this 68# will do for now and keep the above -Wstrict-aliasing=3 in place 69# in newer systems. 70# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h 71# 72# See https://lkml.org/lkml/2006/11/28/253 and https://gcc.gnu.org/gcc-4.8/changes.html, 73# that takes into account Linus's comments (search for Wshadow) for the reasoning about 74# -Wshadow not being interesting before gcc 4.8. 75 76ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3 77EXTRA_WARNINGS += -fno-strict-aliasing 78EXTRA_WARNINGS += -Wno-shadow 79else 80EXTRA_WARNINGS += -Wshadow 81endif 82 83ifneq ($(findstring $(MAKEFLAGS), w),w) 84PRINT_DIR = --no-print-directory 85else 86NO_SUBDIR = : 87endif 88 89ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),) 90 silent=1 91endif 92 93# 94# Define a callable command for descending to a new directory 95# 96# Call by doing: $(call descend,directory[,target]) 97# 98descend = \ 99 +mkdir -p $(OUTPUT)$(1) && \ 100 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 101 102QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir 103QUIET_SUBDIR1 = 104 105ifneq ($(silent),1) 106 ifneq ($(V),1) 107 QUIET_CC = @echo ' CC '$@; 108 QUIET_CC_FPIC = @echo ' CC FPIC '$@; 109 QUIET_AR = @echo ' AR '$@; 110 QUIET_LINK = @echo ' LINK '$@; 111 QUIET_MKDIR = @echo ' MKDIR '$@; 112 QUIET_GEN = @echo ' GEN '$@; 113 QUIET_SUBDIR0 = +@subdir= 114 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \ 115 echo ' SUBDIR '$$subdir; \ 116 $(MAKE) $(PRINT_DIR) -C $$subdir 117 QUIET_FLEX = @echo ' FLEX '$@; 118 QUIET_BISON = @echo ' BISON '$@; 119 120 descend = \ 121 +@echo ' DESCEND '$(1); \ 122 mkdir -p $(OUTPUT)$(1) && \ 123 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2) 124 125 QUIET_CLEAN = @printf ' CLEAN %s\n' $1; 126 QUIET_INSTALL = @printf ' INSTALL %s\n' $1; 127 QUIET_UNINST = @printf ' UNINST %s\n' $1; 128 endif 129endif 130 131pound := \# 132