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 CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
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.
50 $(if $(or $(findstring environment,$(origin $(1))),\
51 $(findstring command line,$(origin $(1)))),,\
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)
62 ifeq ($(CC_NO_CLANG), 1)
63 EXTRA_WARNINGS += -Wstrict-aliasing=3
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
70 # Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
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.
76 ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
77 EXTRA_WARNINGS += -fno-strict-aliasing
78 EXTRA_WARNINGS += -Wno-shadow
80 EXTRA_WARNINGS += -Wshadow
83 ifneq ($(findstring $(MAKEFLAGS), w),w)
84 PRINT_DIR = --no-print-directory
89 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
94 # Define a callable command for descending to a new directory
96 # Call by doing: $(call descend,directory[,target])
99 +mkdir -p $(OUTPUT)$(1) && \
100 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
102 QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
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 '$@;
118 QUIET_BISON = @echo ' BISON '$@;
121 +@echo ' DESCEND '$(1); \
122 mkdir -p $(OUTPUT)$(1) && \
123 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
125 QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
126 QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
127 QUIET_UNINST = @printf ' UNINST %s\n' $1;