projects/linux·blob master · refs

243 lines · 8.4 KiB

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),)
55 ifneq ($(filter %/,$(LLVM)),)
56 LLVM_PREFIX := $(LLVM)
57 else ifneq ($(filter -%,$(LLVM)),)
58 LLVM_SUFFIX := $(LLVM)
59 else ifneq ($(LLVM),1)
60 $(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
61 endif
62
63 $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
64 $(call allow-override,CLANG,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
65 $(call allow-override,HOSTCC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
66 $(call allow-override,AR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
67 $(call allow-override,HOSTAR,$(LLVM_PREFIX)llvm-ar$(LLVM_SUFFIX))
68 $(call allow-override,LD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
69 $(call allow-override,HOSTLD,$(LLVM_PREFIX)ld.lld$(LLVM_SUFFIX))
70 $(call allow-override,CXX,$(LLVM_PREFIX)clang++$(LLVM_SUFFIX))
71 $(call allow-override,STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
72 $(call allow-override,LLVM_STRIP,$(LLVM_PREFIX)llvm-strip$(LLVM_SUFFIX))
73 $(call allow-override,LLC,$(LLVM_PREFIX)llc$(LLVM_SUFFIX))
74 $(call allow-override,LLVM_CONFIG,$(LLVM_PREFIX)llvm-config$(LLVM_SUFFIX))
75 $(call allow-override,LLVM_OBJCOPY,$(LLVM_PREFIX)llvm-objcopy$(LLVM_SUFFIX))
76 $(call allow-override,READELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
77 $(call allow-override,HOSTREADELF,$(LLVM_PREFIX)llvm-readelf$(LLVM_SUFFIX))
78else
79 # Allow setting various cross-compile vars or setting CROSS_COMPILE as a prefix.
80 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
81 $(call allow-override,AR,$(CROSS_COMPILE)ar)
82 $(call allow-override,LD,$(CROSS_COMPILE)ld)
83 $(call allow-override,CXX,$(CROSS_COMPILE)g++)
84 $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
85 $(call allow-override,READELF,$(CROSS_COMPILE)readelf)
86
87 # Host versions aren't prefixed
88 $(call allow-override,HOSTAR,ar)
89 $(call allow-override,HOSTCC,gcc)
90 $(call allow-override,HOSTLD,ld)
91 $(call allow-override,HOSTREADELF,readelf)
92
93 # Some tools still require Clang, LLC and/or LLVM utils
94 $(call allow-override,CLANG,clang)
95 $(call allow-override,LLC,llc)
96 $(call allow-override,LLVM_CONFIG,llvm-config)
97 $(call allow-override,LLVM_OBJCOPY,llvm-objcopy)
98 $(call allow-override,LLVM_STRIP,llvm-strip)
99endif
100
101# The CC_NO_CLANG probe also runs at parse time for targets that never
102# compile, so guard it with 'command -v': when the compiler is not yet
103# installed, e.g. the first install-build-deps run, it would otherwise
104# spew "gcc: not found". Only the first word of CC is consulted, as CC
105# may carry arguments, e.g. 'ccache gcc'. A missing compiler leaves
106# CC_NO_CLANG at 1, as if the probe had failed.
107CC_NO_CLANG := $(shell if command -v $(firstword $(CC)) >/dev/null 2>&1; then $(CC) -dM -E -x c /dev/null; fi | grep -Fq "__clang__"; echo $$?)
108
109# Some tools require bpftool
110SYSTEM_BPFTOOL ?= bpftool
111
112RUSTC ?= rustc
113
114ifeq ($(CC_NO_CLANG), 1)
115EXTRA_WARNINGS += -Wstrict-aliasing=3
116
117else ifneq ($(CROSS_COMPILE),)
118# Allow userspace to override CLANG_CROSS_FLAGS to specify their own
119# sysroots and flags or to avoid the GCC call in pure Clang builds.
120ifeq ($(CLANG_CROSS_FLAGS),)
121CLANG_TARGET := $(notdir $(CROSS_COMPILE:%-=%))
122CLANG_TARGET := $(subst s390-linux,s390x-linux,$(CLANG_TARGET))
123CLANG_CROSS_FLAGS := --target=$(CLANG_TARGET)
124GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)gcc 2>/dev/null))
125ifneq ($(GCC_TOOLCHAIN_DIR),)
126CLANG_CROSS_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
127CLANG_CROSS_FLAGS += --sysroot=$(shell $(CROSS_COMPILE)gcc -print-sysroot)
128CLANG_CROSS_FLAGS += --gcc-toolchain=$(realpath $(GCC_TOOLCHAIN_DIR)/..)
129endif # GCC_TOOLCHAIN_DIR
130endif # CLANG_CROSS_FLAGS
131CFLAGS += $(CLANG_CROSS_FLAGS)
132AFLAGS += $(CLANG_CROSS_FLAGS)
133else
134CLANG_CROSS_FLAGS :=
135endif # CROSS_COMPILE
136
137# Hack to avoid type-punned warnings on old systems such as RHEL5:
138# We should be changing CFLAGS and checking gcc version, but this
139# will do for now and keep the above -Wstrict-aliasing=3 in place
140# in newer systems.
141# Needed for the __raw_cmpxchg in tools/arch/x86/include/asm/cmpxchg.h
142#
143# See https://lore.kernel.org/lkml/[email protected]/
144# and https://gcc.gnu.org/gcc-4.8/changes.html,
145# that takes into account Linus's comments (search for Wshadow) for the reasoning about
146# -Wshadow not being interesting before gcc 4.8.
147
148ifneq ($(filter 3.%,$(MAKE_VERSION)),) # make-3
149EXTRA_WARNINGS += -fno-strict-aliasing
150EXTRA_WARNINGS += -Wno-shadow
151else
152EXTRA_WARNINGS += -Wshadow
153endif
154
155ifneq ($(findstring $(MAKEFLAGS), w),w)
156PRINT_DIR = --no-print-directory
157else
158NO_SUBDIR = :
159endif
160
161# Beautify output
162# ---------------------------------------------------------------------------
163#
164# Most of build commands in Kbuild start with "cmd_". You can optionally define
165# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
166# that command is printed by default.
167#
168# e.g.)
169# quiet_cmd_depmod = DEPMOD $(MODLIB)
170# cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
171#
172# A simple variant is to prefix commands with $(Q) - that's useful
173# for commands that shall be hidden in non-verbose mode.
174#
175# $(Q)$(MAKE) $(build)=scripts/basic
176#
177# To put more focus on warnings, be less verbose as default
178# Use 'make V=1' to see the full commands
179
180ifeq ($(V),1)
181 quiet =
182 Q =
183else
184 quiet = quiet_
185 Q = @
186endif
187
188# If the user is running make -s (silent mode), suppress echoing of commands
189# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
190ifeq ($(filter 3.%,$(MAKE_VERSION)),)
191short-opts := $(firstword -$(MAKEFLAGS))
192else
193short-opts := $(filter-out --%,$(MAKEFLAGS))
194endif
195
196ifneq ($(findstring s,$(short-opts)),)
197 silent=1
198 quiet=silent_
199endif
200
201export quiet Q
202
203#
204# Define a callable command for descending to a new directory
205#
206# Call by doing: $(call descend,directory[,target])
207#
208descend = \
209 +mkdir -p $(OUTPUT)$(1) && \
210 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
211
212QUIET_SUBDIR0 = +$(MAKE) $(COMMAND_O) -C # space to separate -C and subdir
213QUIET_SUBDIR1 =
214
215ifneq ($(silent),1)
216 ifneq ($(V),1)
217 QUIET_CC = @echo ' CC '$@;
218 QUIET_CC_FPIC = @echo ' CC FPIC '$@;
219 QUIET_CLANG = @echo ' CLANG '$@;
220 QUIET_AR = @echo ' AR '$@;
221 QUIET_LINK = @echo ' LINK '$@;
222 QUIET_MKDIR = @echo ' MKDIR '$@;
223 QUIET_GEN = @echo ' GEN '$@;
224 QUIET_SUBDIR0 = +@subdir=
225 QUIET_SUBDIR1 = ;$(NO_SUBDIR) \
226 echo ' SUBDIR '$$subdir; \
227 $(MAKE) $(PRINT_DIR) -C $$subdir
228 QUIET_FLEX = @echo ' FLEX '$@;
229 QUIET_BISON = @echo ' BISON '$@;
230 QUIET_GENSKEL = @echo ' GENSKEL '$@;
231
232 descend = \
233 +@echo ' DESCEND '$(1); \
234 mkdir -p $(OUTPUT)$(1) && \
235 $(MAKE) $(COMMAND_O) subdir=$(if $(subdir),$(subdir)/$(1),$(1)) $(PRINT_DIR) -C $(1) $(2)
236
237 QUIET_CLEAN = @printf ' CLEAN %s\n' $1;
238 QUIET_INSTALL = @printf ' INSTALL %s\n' $1;
239 QUIET_UNINST = @printf ' UNINST %s\n' $1;
240 endif
241endif
242
243pound := \#