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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
41
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.
47define allow-override
48  $(if $(or $(findstring environment,$(origin $(1))),\
49            $(findstring command line,$(origin $(1)))),,\
50    $(eval $(1) = $(2)))
51endef
52
53ifneq ($(LLVM),)
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$(call allow-override,STRIP,llvm-strip)
59else
60# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
61$(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)
66endif
67
68CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
69
70ifneq ($(LLVM),)
71HOSTAR  ?= llvm-ar
72HOSTCC  ?= clang
73HOSTLD  ?= ld.lld
74else
75HOSTAR  ?= ar
76HOSTCC  ?= gcc
77HOSTLD  ?= ld
78endif
79
80ifeq ($(CC_NO_CLANG), 1)
81EXTRA_WARNINGS += -Wstrict-aliasing=3
82endif
83
84# Hack to avoid type-punned warnings on old systems such as RHEL5:
85# We should be changing CFLAGS and checking gcc version, but this
86# will do for now and keep the above -Wstrict-aliasing=3 in place
87# in newer systems.
88# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
89#
90# See https://lkml.org/lkml/2006/11/28/253 and https://gcc.gnu.org/gcc-4.8/changes.html,
91# that takes into account Linus's comments (search for Wshadow) for the reasoning about
92# -Wshadow not being interesting before gcc 4.8.
93
94ifneq ($(filter 3.%,$(MAKE_VERSION)),)  # make-3
95EXTRA_WARNINGS += -fno-strict-aliasing
96EXTRA_WARNINGS += -Wno-shadow
97else
98EXTRA_WARNINGS += -Wshadow
99endif
100
101ifneq ($(findstring $(MAKEFLAGS), w),w)
102PRINT_DIR = --no-print-directory
103else
104NO_SUBDIR = :
105endif
106
107ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
108  silent=1
109endif
110
111#
112# Define a callable command for descending to a new directory
113#
114# Call by doing: $(call descend,directory[,target])
115#
116descend = \
117	+mkdir -p $(OUTPUT)$(1) && \
118	$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
119
120QUIET_SUBDIR0  = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
121QUIET_SUBDIR1  =
122
123ifneq ($(silent),1)
124  ifneq ($(V),1)
125	QUIET_CC       = @echo '  CC       '$@;
126	QUIET_CC_FPIC  = @echo '  CC FPIC  '$@;
127	QUIET_CLANG    = @echo '  CLANG    '$@;
128	QUIET_AR       = @echo '  AR       '$@;
129	QUIET_LINK     = @echo '  LINK     '$@;
130	QUIET_MKDIR    = @echo '  MKDIR    '$@;
131	QUIET_GEN      = @echo '  GEN      '$@;
132	QUIET_SUBDIR0  = +@subdir=
133	QUIET_SUBDIR1  = ;$(NO_SUBDIR) \
134			  echo '  SUBDIR   '$$subdir; \
135			 $(MAKE) $(PRINT_DIR) -C $$subdir
136	QUIET_FLEX     = @echo '  FLEX     '$@;
137	QUIET_BISON    = @echo '  BISON    '$@;
138
139	descend = \
140		+@echo	       '  DESCEND  '$(1); \
141		mkdir -p $(OUTPUT)$(1) && \
142		$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
143
144	QUIET_CLEAN    = @printf '  CLEAN    %s\n' $1;
145	QUIET_INSTALL  = @printf '  INSTALL  %s\n' $1;
146	QUIET_UNINST   = @printf '  UNINST   %s\n' $1;
147  endif
148endif
149
150pound := \#
151