Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1# SPDX-License-Identifier: GPL-2.0
2ifneq ($(O),)
3ifeq ($(origin O), command line)
4 $(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
41EXTRA_WARNINGS += -Wno-type-limits
42
43# Makefiles suck: This macro sets a default value of $(2) for the
44# variable named by $(1), unless the variable has been set by
45# environment or command line. This is necessary for CC and AR
46# because make sets default values, so the simpler ?= approach
47# won't work as expected.
48define allow-override
49 $(if $(or $(findstring environment,$(origin $(1))),\
50 $(findstring command line,$(origin $(1)))),,\
51 $(eval $(1) = $(2)))
52endef
53
54ifneq ($(LLVM),)
55ifneq ($(filter %/,$(LLVM)),)
56LLVM_PREFIX := $(LLVM)
57else ifneq ($(filter -%,$(LLVM)),)
58LLVM_SUFFIX := $(LLVM)
59endif
60
61$(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
62$(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
63$(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
64$(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
65$(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
66else
67# Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
68$(call allow-override,CC,$(CROSS_COMPILE)gcc)
69$(call allow-override,AR,$(CROSS_COMPILE)ar)
70$(call allow-override,LD,$(CROSS_COMPILE)ld)
71$(call allow-override,CXX,$(CROSS_COMPILE)g++)
72$(call allow-override,STRIP,$(CROSS_COMPILE)strip)
73endif
74
75CC_NO_CLANG := $(shell $(CC) -dM -E -x c /dev/null | grep -Fq "__clang__"; echo $$?)
76
77ifneq ($(LLVM),)
78HOSTAR ?= $(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX)
79HOSTCC ?= $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
80HOSTLD ?= $(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX)
81else
82HOSTAR ?= ar
83HOSTCC ?= gcc
84HOSTLD ?= ld
85endif
86
87# Some tools require Clang, LLC and/or LLVM utils
88CLANG ?= clang
89LLC ?= llc
90LLVM_CONFIG ?= llvm-config
91LLVM_OBJCOPY ?= llvm-objcopy
92LLVM_STRIP ?= llvm-strip
93
94# Some tools require bpftool
95SYSTEM_BPFTOOL ?= bpftool
96
97RUSTC ?= rustc
98
99ifeq ($(CC_NO_CLANG), 1)
100EXTRA_WARNINGS += -Wstrict-aliasing=3
101
102else ifneq ($(CROSS_COMPILE),)
103# Allow userspace to override CLANG_CROSS_FLAGS to specify their own
104# sysroots and flags or to avoid the GCC call in pure Clang builds.
105ifeq ($(CLANG_CROSS_FLAGS),)
106CLANG_TARGET := $(notdir $(CROSS_COMPILE:%-=%))
107CLANG_TARGET := $(subst s390-linux,s390x-linux,$(CLANG_TARGET))
108CLANG_CROSS_FLAGS := --target=$(CLANG_TARGET)
109GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null))
110ifneq ($(GCC_TOOLCHAIN_DIR),)
111CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
112CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot)
113CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..)
114endif # GCC_TOOLCHAIN_DIR
115endif # CLANG_CROSS_FLAGS
116CFLAGS += $(CLANG_CROSS_FLAGS)
117AFLAGS += $(CLANG_CROSS_FLAGS)
118else
119CLANG_CROSS_FLAGS :=
120endif # CROSS_COMPILE
121
122# Hack to avoid type-punned warnings on old systems such as RHEL5:
123# We should be changing CFLAGS and checking gcc version, but this
124# will do for now and keep the above -Wstrict-aliasing=3 in place
125# in newer systems.
126# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
127#
128# See https://lore.kernel.org/lkml/9a8748490611281710g78402fbeh8ff7fcc162dbcbca@mail.gmail.com/
129# and https://gcc.gnu.org/gcc-4.8/changes.html,
130# that takes into account Linus's comments (search for Wshadow) for the reasoning about
131# -Wshadow not being interesting before gcc 4.8.
132
133ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
134EXTRA_WARNINGS += -fno-strict-aliasing
135EXTRA_WARNINGS += -Wno-shadow
136else
137EXTRA_WARNINGS += -Wshadow
138endif
139
140ifneq ($(findstring $(MAKEFLAGS), w),w)
141PRINT_DIR = --no-print-directory
142else
143NO_SUBDIR = :
144endif
145
146# Beautify output
147# ---------------------------------------------------------------------------
148#
149# Most of build commands in Kbuild start with "cmd_". You can optionally define
150# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
151# that command is printed by default.
152#
153# e.g.)
154# quiet_cmd_depmod = DEPMOD $(MODLIB)
155# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
156#
157# A simple variant is to prefix commands with $(Q) - that's useful
158# for commands that shall be hidden in non-verbose mode.
159#
160# $(Q)$(MAKE) $(build)=scripts/basic
161#
162# To put more focus on warnings, be less verbose as default
163# Use 'make V=1' to see the full commands
164
165ifeq ($(V),1)
166 quiet =
167 Q =
168else
169 quiet = quiet_
170 Q = @
171endif
172
173# If the user is running make -s (silent mode), suppress echoing of commands
174# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
175ifeq ($(filter 3.%,$(MAKE_VERSION)),)
176short-opts := $(firstword -$(MAKEFLAGS))
177else
178short-opts := $(filter-out --%,$(MAKEFLAGS))
179endif
180
181ifneq ($(findstring s,$(short-opts)),)
182 silent=1
183 quiet=silent_
184endif
185
186export quiet Q
187
188#
189# Define a callable command for descending to a new directory
190#
191# Call by doing: $(call descend,directory[,target])
192#
193descend = \
194 +mkdir -p $(OUTPUT)$(1) && \
195 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
196
197QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
198QUIET_SUBDIR1 =
199
200ifneq ($(silent),1)
201 ifneq ($(V),1)
202 QUIET_CC = @echo ' CC '$@;
203 QUIET_CC_FPIC = @echo ' CC FPIC '$@;
204 QUIET_CLANG = @echo ' CLANG '$@;
205 QUIET_AR = @echo ' AR '$@;
206 QUIET_LINK = @echo ' LINK '$@;
207 QUIET_MKDIR = @echo ' MKDIR '$@;
208 QUIET_GEN = @echo ' GEN '$@;
209 QUIET_SUBDIR0 = +@subdir=
210 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \
211 echo ' SUBDIR '$$subdir; \
212 $(MAKE) $(PRINT_DIR) -C $$subdir
213 QUIET_FLEX = @echo ' FLEX '$@;
214 QUIET_BISON = @echo ' BISON '$@;
215 QUIET_GENSKEL = @echo ' GENSKEL '$@;
216
217 descend = \
218 +@echo ' DESCEND '$(1); \
219 mkdir -p $(OUTPUT)$(1) && \
220 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
221
222 QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
223 QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
224 QUIET_UNINST = @printf ' UNINST %s\n' $1;
225 endif
226endif
227
228pound := \#