1 # SPDX-License-Identifier: GPL-2.0
3 ifeq ($(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)
14 # check that the output directory actually exists
16 OUTDIR := $(shell cd $(OUTPUT) && pwd)
17 $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
21 # Include saner warnings here, which can catch bugs:
23 EXTRA_WARNINGS := -Wbad-function-cast
24 EXTRA_WARNINGS += -Wdeclaration-after-statement
25 EXTRA_WARNINGS += -Wformat-security
26 EXTRA_WARNINGS += -Wformat-y2k
27 EXTRA_WARNINGS += -Winit-self
28 EXTRA_WARNINGS += -Wmissing-declarations
29 EXTRA_WARNINGS += -Wmissing-prototypes
30 EXTRA_WARNINGS += -Wnested-externs
31 EXTRA_WARNINGS += -Wno-system-headers
32 EXTRA_WARNINGS += -Wold-style-definition
33 EXTRA_WARNINGS += -Wpacked
34 EXTRA_WARNINGS += -Wredundant-decls
35 EXTRA_WARNINGS += -Wstrict-prototypes
36 EXTRA_WARNINGS += -Wswitch-default
37 EXTRA_WARNINGS += -Wswitch-enum
38 EXTRA_WARNINGS += -Wundef
39 EXTRA_WARNINGS += -Wwrite-strings
40 EXTRA_WARNINGS += -Wformat
42 # Makefiles suck: This macro sets a default value of $(2) for the
43 # variable named by $(1), unless the variable has been set by
44 # environment or command line. This is necessary for CC and AR
45 # because make sets default values, so the simpler ?= approach
46 # won't work as expected.
48 $(if $(or $(findstring environment,$(origin $(1))),\
49 $(findstring command line,$(origin $(1)))),,\
54 $(call allow-override,CC,clang)
55 $(call allow-override,AR,llvm-ar)
56 $(call allow-override,LD,ld.lld)
57 $(call allow-override,CXX,clang++)
58 $(call allow-override,STRIP,llvm-strip)
60 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
61 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
62 $(call allow-override,AR,$(CROSS_COMPILE)ar)
63 $(call allow-override,LD,$(CROSS_COMPILE)ld)
64 $(call allow-override,CXX,$(CROSS_COMPILE)g++)
65 $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
68 CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
80 ifeq ($(CC_NO_CLANG), 1)
81 EXTRA_WARNINGS += -Wstrict-aliasing=3
84 # Hack to avoid type-punned warnings on old systems such as RHEL5:
85 # We should be changing CFLAGS and checking gcc version, but this
86 # will do for now and keep the above -Wstrict-aliasing=3 in place
88 # Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
90 # See https://lkml.org/lkml/2006/11/28/253 and https://gcc.gnu.org/gcc-4.8/changes.html,
91 # that takes into account Linus's comments (search for Wshadow) for the reasoning about
92 # -Wshadow not being interesting before gcc 4.8.
94 ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
95 EXTRA_WARNINGS += -fno-strict-aliasing
96 EXTRA_WARNINGS += -Wno-shadow
98 EXTRA_WARNINGS += -Wshadow
101 ifneq ($(findstring $(MAKEFLAGS), w),w)
102 PRINT_DIR = --no-print-directory
107 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
112 # Define a callable command for descending to a new directory
114 # Call by doing: $(call descend,directory[,target])
117 +mkdir -p $(OUTPUT)$(1) && \
118 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
120 QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
125 QUIET_CC = @echo ' CC '$@;
126 QUIET_CC_FPIC = @echo ' CC FPIC '$@;
127 QUIET_CLANG = @echo ' CLANG '$@;
128 QUIET_AR = @echo ' AR '$@;
129 QUIET_LINK = @echo ' LINK '$@;
130 QUIET_MKDIR = @echo ' MKDIR '$@;
131 QUIET_GEN = @echo ' GEN '$@;
132 QUIET_SUBDIR0 = +@subdir=
133 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \
134 echo ' SUBDIR '$$subdir; \
135 $(MAKE) $(PRINT_DIR) -C $$subdir
136 QUIET_FLEX = @echo ' FLEX '$@;
137 QUIET_BISON = @echo ' BISON '$@;
140 +@echo ' DESCEND '$(1); \
141 mkdir -p $(OUTPUT)$(1) && \
142 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
144 QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
145 QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
146 QUIET_UNINST = @printf ' UNINST %s\n' $1;