1ifneq ($(O),)
2ifeq ($(origin O), command line)
3	ABSOLUTE_O := $(realpath $(O))
4	dummy := $(if $(ABSOLUTE_O),,$(error O=$(O) does not exist))
5	OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
6	COMMAND_O := O=$(ABSOLUTE_O)
7ifeq ($(objtree),)
8	objtree := $(O)
9endif
10endif
11endif
12
13# check that the output directory actually exists
14ifneq ($(OUTPUT),)
15OUTDIR := $(realpath $(OUTPUT))
16$(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
17endif
18
19#
20# Include saner warnings here, which can catch bugs:
21#
22EXTRA_WARNINGS := -Wbad-function-cast
23EXTRA_WARNINGS += -Wdeclaration-after-statement
24EXTRA_WARNINGS += -Wformat-security
25EXTRA_WARNINGS += -Wformat-y2k
26EXTRA_WARNINGS += -Winit-self
27EXTRA_WARNINGS += -Wmissing-declarations
28EXTRA_WARNINGS += -Wmissing-prototypes
29EXTRA_WARNINGS += -Wnested-externs
30EXTRA_WARNINGS += -Wno-system-headers
31EXTRA_WARNINGS += -Wold-style-definition
32EXTRA_WARNINGS += -Wpacked
33EXTRA_WARNINGS += -Wredundant-decls
34EXTRA_WARNINGS += -Wshadow
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 $$?)
43
44ifeq ($(CC_NO_CLANG), 1)
45EXTRA_WARNINGS += -Wstrict-aliasing=3
46endif
47
48# Hack to avoid type-punned warnings on old systems such as RHEL5:
49# We should be changing CFLAGS and checking gcc version, but this
50# will do for now and keep the above -Wstrict-aliasing=3 in place
51# in newer systems.
52# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
53ifneq ($(filter 3.%,$(MAKE_VERSION)),)  # make-3
54EXTRA_WARNINGS += -fno-strict-aliasing
55endif
56
57ifneq ($(findstring $(MAKEFLAGS), w),w)
58PRINT_DIR = --no-print-directory
59else
60NO_SUBDIR = :
61endif
62
63ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
64  silent=1
65endif
66
67#
68# Define a callable command for descending to a new directory
69#
70# Call by doing: $(call descend,directory[,target])
71#
72descend = \
73	+mkdir -p $(OUTPUT)$(1) && \
74	$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
75
76QUIET_SUBDIR0  = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
77QUIET_SUBDIR1  =
78
79ifneq ($(silent),1)
80  ifneq ($(V),1)
81	QUIET_CC       = @echo '  CC       '$@;
82	QUIET_CC_FPIC  = @echo '  CC FPIC  '$@;
83	QUIET_AR       = @echo '  AR       '$@;
84	QUIET_LINK     = @echo '  LINK     '$@;
85	QUIET_MKDIR    = @echo '  MKDIR    '$@;
86	QUIET_GEN      = @echo '  GEN      '$@;
87	QUIET_SUBDIR0  = +@subdir=
88	QUIET_SUBDIR1  = ;$(NO_SUBDIR) \
89			  echo '  SUBDIR   '$$subdir; \
90			 $(MAKE) $(PRINT_DIR) -C $$subdir
91	QUIET_FLEX     = @echo '  FLEX     '$@;
92	QUIET_BISON    = @echo '  BISON    '$@;
93
94	descend = \
95		+@echo	       '  DESCEND  '$(1); \
96		mkdir -p $(OUTPUT)$(1) && \
97		$(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
98
99	QUIET_CLEAN    = @printf '  CLEAN    %s\n' $1;
100	QUIET_INSTALL  = @printf '  INSTALL  %s\n' $1;
101  endif
102endif
103