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
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
62ifneq ($(LLVM),)
63HOSTAR  ?= llvm-ar
64HOSTCC  ?= clang
65HOSTLD  ?= ld.lld
66else
67HOSTAR  ?= ar
68HOSTCC  ?= gcc
69HOSTLD  ?= ld
70endif
71
72ifeq ($(CC_NO_CLANG), 1)
73EXTRA_WARNINGS += -Wstrict-aliasing=3
74endif
75
76# Hack to avoid type-punned warnings on old systems such as RHEL5:
77# We should be changing CFLAGS and checking gcc version, but this
78# will do for now and keep the above -Wstrict-aliasing=3 in place
79# in newer systems.
80# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
81#
82# See https://lkml.org/lkml/2006/11/28/253 and https://gcc.gnu.org/gcc-4.8/changes.html,
83# that takes into account Linus's comments (search for Wshadow) for the reasoning about
84# -Wshadow not being interesting before gcc 4.8.
85
86ifneq ($(filter 3.%,$(MAKE_VERSION)),)  # make-3
87EXTRA_WARNINGS += -fno-strict-aliasing
88EXTRA_WARNINGS += -Wno-shadow
89else
90EXTRA_WARNINGS += -Wshadow
91endif
92
93ifneq ($(findstring $(MAKEFLAGS), w),w)
94PRINT_DIR = --no-print-directory
95else
96NO_SUBDIR = :
97endif
98
99ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
100  silent=1
101endif
102
103#
104# Define a callable command for descending to a new directory
105#
106# Call by doing: $(call descend,directory[,target])
107#
108descend = \
109	+mkdir -p $(OUTPUT)$(1) && \
110	$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
111
112QUIET_SUBDIR0  = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
113QUIET_SUBDIR1  =
114
115ifneq ($(silent),1)
116  ifneq ($(V),1)
117	QUIET_CC       = @echo '  CC       '$@;
118	QUIET_CC_FPIC  = @echo '  CC FPIC  '$@;
119	QUIET_CLANG    = @echo '  CLANG    '$@;
120	QUIET_AR       = @echo '  AR       '$@;
121	QUIET_LINK     = @echo '  LINK     '$@;
122	QUIET_MKDIR    = @echo '  MKDIR    '$@;
123	QUIET_GEN      = @echo '  GEN      '$@;
124	QUIET_SUBDIR0  = +@subdir=
125	QUIET_SUBDIR1  = ;$(NO_SUBDIR) \
126			  echo '  SUBDIR   '$$subdir; \
127			 $(MAKE) $(PRINT_DIR) -C $$subdir
128	QUIET_FLEX     = @echo '  FLEX     '$@;
129	QUIET_BISON    = @echo '  BISON    '$@;
130	QUIET_GENSKEL  = @echo '  GEN-SKEL '$@;
131
132	descend = \
133		+@echo	       '  DESCEND  '$(1); \
134		mkdir -p $(OUTPUT)$(1) && \
135		$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
136
137	QUIET_CLEAN    = @printf '  CLEAN    %s\n' $1;
138	QUIET_INSTALL  = @printf '  INSTALL  %s\n' $1;
139	QUIET_UNINST   = @printf '  UNINST   %s\n' $1;
140  endif
141endif
142
143pound := \#
144