4 # Warning flags for compiling the kernel and components of the kernel:
6 CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
7 -Wmissing-prototypes -Wpointer-arith -Wcast-qual \
8 -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
9 -Wmissing-include-dirs -fdiagnostics-show-option \
10 -Wno-unknown-pragmas \
13 # The following flags are next up for working on:
16 # Disable a few warnings for clang, since there are several places in the
17 # kernel where fixing them is more trouble than it is worth, or where there is
19 .if ${COMPILER_TYPE} == "clang"
20 NO_WCONSTANT_CONVERSION= -Wno-error-constant-conversion
21 NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
22 NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
23 NO_WSELF_ASSIGN= -Wno-self-assign
24 NO_WUNNEEDED_INTERNAL_DECL= -Wno-error-unneeded-internal-declaration
25 NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
26 NO_WCAST_QUAL= -Wno-error-cast-qual
27 NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare
28 # Several other warnings which might be useful in some cases, but not severe
29 # enough to error out the whole kernel build. Display them anyway, so there is
30 # some incentive to fix them eventually.
31 CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
32 -Wno-error-parentheses-equality -Wno-error-unused-function \
33 -Wno-error-pointer-sign
34 .if ${COMPILER_VERSION} >= 30700
35 CWARNEXTRA+= -Wno-error-shift-negative-value
37 .if ${COMPILER_VERSION} >= 40000
38 CWARNEXTRA+= -Wno-address-of-packed-member
41 CLANG_NO_IAS= -no-integrated-as
44 .if ${COMPILER_TYPE} == "gcc"
45 .if ${COMPILER_VERSION} >= 40800
46 # Catch-all for all the things that are in our tree, but for which we're
47 # not yet ready for this compiler.
48 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
49 CWARNEXTRA?= -Wno-error=address \
50 -Wno-error=aggressive-loop-optimizations \
51 -Wno-error=array-bounds \
52 -Wno-error=attributes \
53 -Wno-error=cast-qual \
54 -Wno-error=enum-compare \
56 -Wno-error=maybe-uninitialized \
58 -Wno-error=sequence-point \
59 -Wno-unused-but-set-variable
60 .if ${COMPILER_VERSION} >= 60100
61 CWARNEXTRA+= -Wno-error=misleading-indentation \
62 -Wno-error=nonnull-compare \
63 -Wno-error=shift-overflow \
64 -Wno-error=tautological-compare \
65 -Wno-format-zero-length
67 .if ${COMPILER_VERSION} >= 70200
68 CWARNEXTRA+= -Wno-error=memset-elt-size
70 .if ${COMPILER_VERSION} >= 80000
71 CWARNEXTRA+= -Wno-error=packed-not-aligned
74 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
75 CWARNEXTRA?= -Wno-uninitialized
76 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
77 # the few files that are already known to generate cast-qual warnings.
78 NO_WCAST_QUAL= -Wno-cast-qual
82 # External compilers may not support our format extensions. Allow them
83 # to be disabled. WARNING: format checking is disabled in this case.
84 .if ${MK_FORMAT_EXTENSIONS} == "no"
85 FORMAT_EXTENSIONS= -Wno-format
86 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
87 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
89 FORMAT_EXTENSIONS= -fformat-extensions
93 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
94 # and above adds code to the entry and exit point of every function to align the
95 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
96 # per function call. While the 16-byte alignment may benefit micro benchmarks,
97 # it is probably an overall loss as it makes the code bigger (less efficient
98 # use of code cache tag lines) and uses more stack (less efficient use of data
99 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
100 # operations inside the kernel itself. These operations are exclusively
101 # reserved for user applications.
104 # Setting -mno-mmx implies -mno-3dnow
105 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
108 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
109 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
111 .if ${MACHINE_CPUARCH} == "i386"
112 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
113 CFLAGS.clang+= -mno-aes -mno-avx
114 CFLAGS+= -mno-mmx -mno-sse -msoft-float
118 .if ${MACHINE_CPUARCH} == "arm"
122 .if ${MACHINE_CPUARCH} == "aarch64"
123 # We generally don't want fpu instructions in the kernel.
124 CFLAGS += -mgeneral-regs-only
125 # Reserve x18 for pcpu data
126 CFLAGS += -ffixed-x18
130 .if ${MACHINE_CPUARCH} == "riscv"
131 CFLAGS.gcc+= -mcmodel=medany -march=rv64imafdc -mabi=lp64
136 # For sparc64 we want the medany code model so modules may be located
137 # anywhere in the 64-bit address space. We also tell GCC to use floating
138 # point emulation. This avoids using floating point registers for integer
139 # operations which it has a tendency to do.
141 .if ${MACHINE_CPUARCH} == "sparc64"
142 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
143 CFLAGS.gcc+= -mcmodel=medany -msoft-float
148 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
149 # operations inside the kernel itself. These operations are exclusively
150 # reserved for user applications.
153 # Setting -mno-mmx implies -mno-3dnow
154 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
157 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
158 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
159 # (-mfpmath= is not supported)
161 .if ${MACHINE_CPUARCH} == "amd64"
162 CFLAGS.clang+= -mno-aes -mno-avx
163 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
164 -fno-asynchronous-unwind-tables
169 # For PowerPC we tell gcc to use floating point emulation. This avoids using
170 # floating point registers for integer operations which it has a tendency to do.
171 # Also explicitly disable Altivec instructions inside the kernel.
173 .if ${MACHINE_CPUARCH} == "powerpc"
174 CFLAGS+= -mno-altivec -msoft-float
178 .if ${MACHINE_ARCH} == "powerpcspe"
179 CFLAGS.gcc+= -mno-spe
183 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
184 # DDB happy. ELFv2, if available, has some other efficiency benefits.
186 .if ${MACHINE_ARCH} == "powerpc64"
187 .if ${COMPILER_VERSION} >= 40900
188 CFLAGS.gcc+= -mabi=elfv2
190 CFLAGS.gcc+= -mcall-aixdesc
192 CFLAGS.clang+= -mabi=elfv2
196 # For MIPS we also tell gcc to use floating point emulation
198 .if ${MACHINE_CPUARCH} == "mips"
199 CFLAGS+= -msoft-float
204 # GCC 3.0 and above like to do certain optimizations based on the
205 # assumption that the program is linked against libc. Stop this.
207 CFLAGS+= -ffreestanding
210 # The C standard leaves signed integer overflow behavior undefined.
211 # gcc and clang opimizers take advantage of this. The kernel makes
212 # use of signed integer wraparound mechanics so we need the compiler
213 # to treat it as a wraparound and not take shortcuts.
220 .if ${MK_SSP} != "no" && \
221 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
222 CFLAGS+= -fstack-protector
226 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
228 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
229 ${MK_KERNEL_RETPOLINE} != "no"
234 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
235 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
236 # cope well with DWARF 4, so force it to genereate DWARF2, which they
237 # understand. Do this unconditionally as it is harmless when not needed,
238 # but critical for these newer versions.
240 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
244 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
245 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
247 # Tell bmake not to mistake standard targets for things to be searched for
248 # or expect to ever be up-to-date.
249 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
250 beforelinking build build-tools buildfiles buildincludes \
251 checkdpadd clean cleandepend cleandir cleanobj configure \
252 depend distclean distribute exe \
253 html includes install installfiles installincludes \
254 obj objlink objs objwarn \
255 realinstall regress \
258 .PHONY: ${PHONY_NOTMAIN}
259 .NOTMAIN: ${PHONY_NOTMAIN}
264 CFLAGS+= -traditional
265 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
266 CFLAGS+= -std=iso9899:1990
267 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
268 CFLAGS+= -std=iso9899:199409
269 .elif ${CSTD} == "c99"
270 CFLAGS+= -std=iso9899:1999
272 CFLAGS+= -std=${CSTD}
275 # Set target-specific linker emulation name.
276 LD_EMULATION_aarch64=aarch64elf
277 LD_EMULATION_amd64=elf_x86_64_fbsd
278 LD_EMULATION_arm=armelf_fbsd
279 LD_EMULATION_armv6=armelf_fbsd
280 LD_EMULATION_armv7=armelf_fbsd
281 LD_EMULATION_i386=elf_i386_fbsd
282 LD_EMULATION_mips= elf32btsmip_fbsd
283 LD_EMULATION_mipshf= elf32btsmip_fbsd
284 LD_EMULATION_mips64= elf64btsmip_fbsd
285 LD_EMULATION_mips64hf= elf64btsmip_fbsd
286 LD_EMULATION_mipsel= elf32ltsmip_fbsd
287 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
288 LD_EMULATION_mips64el= elf64ltsmip_fbsd
289 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
290 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
291 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
292 LD_EMULATION_powerpc= elf32ppc_fbsd
293 LD_EMULATION_powerpcspe= elf32ppc_fbsd
294 LD_EMULATION_powerpc64= elf64ppc_fbsd
295 LD_EMULATION_riscv64= elf64lriscv
296 LD_EMULATION_sparc64= elf64_sparc_fbsd
297 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}