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
79 NO_WNONNULL= -Wno-nonnull
83 # External compilers may not support our format extensions. Allow them
84 # to be disabled. WARNING: format checking is disabled in this case.
85 .if ${MK_FORMAT_EXTENSIONS} == "no"
86 FORMAT_EXTENSIONS= -Wno-format
87 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
88 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
90 FORMAT_EXTENSIONS= -fformat-extensions
94 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
95 # and above adds code to the entry and exit point of every function to align the
96 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
97 # per function call. While the 16-byte alignment may benefit micro benchmarks,
98 # it is probably an overall loss as it makes the code bigger (less efficient
99 # use of code cache tag lines) and uses more stack (less efficient use of data
100 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
101 # operations inside the kernel itself. These operations are exclusively
102 # reserved for user applications.
105 # Setting -mno-mmx implies -mno-3dnow
106 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
109 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
110 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
112 .if ${MACHINE_CPUARCH} == "i386"
113 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
114 CFLAGS.clang+= -mno-aes -mno-avx
115 CFLAGS+= -mno-mmx -mno-sse -msoft-float
119 .if ${MACHINE_CPUARCH} == "arm"
123 .if ${MACHINE_CPUARCH} == "aarch64"
124 # We generally don't want fpu instructions in the kernel.
125 CFLAGS += -mgeneral-regs-only
126 # Reserve x18 for pcpu data
127 CFLAGS += -ffixed-x18
131 .if ${MACHINE_CPUARCH} == "riscv"
132 CFLAGS.gcc+= -mcmodel=medany -march=rv64imafdc -mabi=lp64
137 # For sparc64 we want the medany code model so modules may be located
138 # anywhere in the 64-bit address space. We also tell GCC to use floating
139 # point emulation. This avoids using floating point registers for integer
140 # operations which it has a tendency to do.
142 .if ${MACHINE_CPUARCH} == "sparc64"
143 CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
144 CFLAGS.gcc+= -mcmodel=medany -msoft-float
149 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
150 # operations inside the kernel itself. These operations are exclusively
151 # reserved for user applications.
154 # Setting -mno-mmx implies -mno-3dnow
155 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
158 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
159 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
160 # (-mfpmath= is not supported)
162 .if ${MACHINE_CPUARCH} == "amd64"
163 CFLAGS.clang+= -mno-aes -mno-avx
164 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
165 -fno-asynchronous-unwind-tables
170 # For PowerPC we tell gcc to use floating point emulation. This avoids using
171 # floating point registers for integer operations which it has a tendency to do.
172 # Also explicitly disable Altivec instructions inside the kernel.
174 .if ${MACHINE_CPUARCH} == "powerpc"
175 CFLAGS+= -mno-altivec -msoft-float
179 .if ${MACHINE_ARCH} == "powerpcspe"
180 CFLAGS.gcc+= -mno-spe
184 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
185 # DDB happy. ELFv2, if available, has some other efficiency benefits.
187 .if ${MACHINE_ARCH} == "powerpc64"
188 .if ${COMPILER_VERSION} >= 40900
189 CFLAGS.gcc+= -mabi=elfv2
191 CFLAGS.gcc+= -mcall-aixdesc
193 CFLAGS.clang+= -mabi=elfv2
197 # For MIPS we also tell gcc to use floating point emulation
199 .if ${MACHINE_CPUARCH} == "mips"
200 CFLAGS+= -msoft-float
205 # GCC 3.0 and above like to do certain optimizations based on the
206 # assumption that the program is linked against libc. Stop this.
208 CFLAGS+= -ffreestanding
211 # The C standard leaves signed integer overflow behavior undefined.
212 # gcc and clang opimizers take advantage of this. The kernel makes
213 # use of signed integer wraparound mechanics so we need the compiler
214 # to treat it as a wraparound and not take shortcuts.
221 .if ${MK_SSP} != "no" && \
222 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
223 CFLAGS+= -fstack-protector
227 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
229 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
230 ${MK_KERNEL_RETPOLINE} != "no"
235 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
236 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
237 # cope well with DWARF 4, so force it to genereate DWARF2, which they
238 # understand. Do this unconditionally as it is harmless when not needed,
239 # but critical for these newer versions.
241 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
245 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
246 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
248 # Tell bmake not to mistake standard targets for things to be searched for
249 # or expect to ever be up-to-date.
250 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
251 beforelinking build build-tools buildfiles buildincludes \
252 checkdpadd clean cleandepend cleandir cleanobj configure \
253 depend distclean distribute exe \
254 html includes install installfiles installincludes \
255 obj objlink objs objwarn \
256 realinstall regress \
259 .PHONY: ${PHONY_NOTMAIN}
260 .NOTMAIN: ${PHONY_NOTMAIN}
265 CFLAGS+= -traditional
266 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
267 CFLAGS+= -std=iso9899:1990
268 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
269 CFLAGS+= -std=iso9899:199409
270 .elif ${CSTD} == "c99"
271 CFLAGS+= -std=iso9899:1999
273 CFLAGS+= -std=${CSTD}
276 # Set target-specific linker emulation name.
277 LD_EMULATION_aarch64=aarch64elf
278 LD_EMULATION_amd64=elf_x86_64_fbsd
279 LD_EMULATION_arm=armelf_fbsd
280 LD_EMULATION_armv6=armelf_fbsd
281 LD_EMULATION_armv7=armelf_fbsd
282 LD_EMULATION_i386=elf_i386_fbsd
283 LD_EMULATION_mips= elf32btsmip_fbsd
284 LD_EMULATION_mipshf= elf32btsmip_fbsd
285 LD_EMULATION_mips64= elf64btsmip_fbsd
286 LD_EMULATION_mips64hf= elf64btsmip_fbsd
287 LD_EMULATION_mipsel= elf32ltsmip_fbsd
288 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
289 LD_EMULATION_mips64el= elf64ltsmip_fbsd
290 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
291 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
292 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
293 LD_EMULATION_powerpc= elf32ppc_fbsd
294 LD_EMULATION_powerpcspe= elf32ppc_fbsd
295 LD_EMULATION_powerpc64= elf64ppc_fbsd
296 LD_EMULATION_riscv64= elf64lriscv
297 LD_EMULATION_sparc64= elf64_sparc_fbsd
298 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}