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 CWARNEXTRA+= -Wno-error-shift-negative-value
35 CWARNEXTRA+= -Wno-address-of-packed-member
36 .if ${COMPILER_VERSION} >= 100000
37 NO_WMISLEADING_INDENTATION= -Wno-misleading-indentation
41 .if ${COMPILER_TYPE} == "gcc"
42 # Catch-all for all the things that are in our tree, but for which we're
43 # not yet ready for this compiler.
44 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
45 CWARNEXTRA?= -Wno-error=address \
46 -Wno-error=aggressive-loop-optimizations \
47 -Wno-error=array-bounds \
48 -Wno-error=attributes \
49 -Wno-error=cast-qual \
50 -Wno-error=enum-compare \
52 -Wno-error=maybe-uninitialized \
53 -Wno-error=misleading-indentation \
54 -Wno-error=nonnull-compare \
56 -Wno-error=sequence-point \
57 -Wno-error=shift-overflow \
58 -Wno-error=tautological-compare \
59 -Wno-unused-but-set-variable
60 .if ${COMPILER_VERSION} >= 70100
61 CWARNEXTRA+= -Wno-error=stringop-overflow
63 .if ${COMPILER_VERSION} >= 70200
64 CWARNEXTRA+= -Wno-error=memset-elt-size
66 .if ${COMPILER_VERSION} >= 80000
67 CWARNEXTRA+= -Wno-error=packed-not-aligned
69 .if ${COMPILER_VERSION} >= 90100
70 CWARNEXTRA+= -Wno-address-of-packed-member
74 # This warning is utter nonsense
75 CWARNFLAGS+= -Wno-format-zero-length
77 # External compilers may not support our format extensions. Allow them
78 # to be disabled. WARNING: format checking is disabled in this case.
79 .if ${MK_FORMAT_EXTENSIONS} == "no"
80 FORMAT_EXTENSIONS= -Wno-format
81 .elif ${COMPILER_TYPE} == "clang"
82 FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
84 FORMAT_EXTENSIONS= -fformat-extensions
88 # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
89 # and above adds code to the entry and exit point of every function to align the
90 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
91 # per function call. While the 16-byte alignment may benefit micro benchmarks,
92 # it is probably an overall loss as it makes the code bigger (less efficient
93 # use of code cache tag lines) and uses more stack (less efficient use of data
94 # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
95 # operations inside the kernel itself. These operations are exclusively
96 # reserved for user applications.
99 # Setting -mno-mmx implies -mno-3dnow
100 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
103 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
104 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
106 .if ${MACHINE_CPUARCH} == "i386"
107 CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
108 CFLAGS.clang+= -mno-aes -mno-avx
109 CFLAGS+= -mno-mmx -mno-sse -msoft-float
113 .if ${MACHINE_CPUARCH} == "arm"
117 .if ${MACHINE_CPUARCH} == "aarch64"
118 # We generally don't want fpu instructions in the kernel.
119 CFLAGS += -mgeneral-regs-only
120 # Reserve x18 for pcpu data
121 CFLAGS += -ffixed-x18
126 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
127 # point registers within the kernel. However, for kernels supporting hardware
128 # float (FPE), we have to include that in the march so we can have limited
129 # floating point support in context switching needed for that. This is different
130 # than userland where we use a hard-float ABI (lp64d).
132 # We also specify the "medium" code model, which generates code suitable for a
133 # 2GiB addressing range located at any offset, allowing modules to be located
134 # anywhere in the 64-bit address space. Note that clang and GCC refer to this
135 # code model as "medium" and "medany" respectively.
137 .if ${MACHINE_CPUARCH} == "riscv"
138 CFLAGS+= -march=rv64imafdc
140 CFLAGS.clang+= -mcmodel=medium
141 CFLAGS.gcc+= -mcmodel=medany
144 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
150 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
151 # operations inside the kernel itself. These operations are exclusively
152 # reserved for user applications.
155 # Setting -mno-mmx implies -mno-3dnow
156 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
159 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
160 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
161 # (-mfpmath= is not supported)
163 .if ${MACHINE_CPUARCH} == "amd64"
164 CFLAGS.clang+= -mno-aes -mno-avx
165 CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
166 -fno-asynchronous-unwind-tables
171 # For PowerPC we tell gcc to use floating point emulation. This avoids using
172 # floating point registers for integer operations which it has a tendency to do.
173 # Also explicitly disable Altivec instructions inside the kernel.
175 .if ${MACHINE_CPUARCH} == "powerpc"
176 CFLAGS+= -mno-altivec -msoft-float
180 .if ${MACHINE_ARCH} == "powerpcspe"
181 CFLAGS.gcc+= -mno-spe
185 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
186 # DDB happy. ELFv2, if available, has some other efficiency benefits.
188 .if ${MACHINE_ARCH:Mpowerpc64*} != ""
193 # For MIPS we also tell gcc to use floating point emulation
195 .if ${MACHINE_CPUARCH} == "mips"
196 CFLAGS+= -msoft-float
201 # GCC 3.0 and above like to do certain optimizations based on the
202 # assumption that the program is linked against libc. Stop this.
204 CFLAGS+= -ffreestanding
207 # The C standard leaves signed integer overflow behavior undefined.
208 # gcc and clang opimizers take advantage of this. The kernel makes
209 # use of signed integer wraparound mechanics so we need the compiler
210 # to treat it as a wraparound and not take shortcuts.
217 .if ${MK_SSP} != "no" && \
218 ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
219 CFLAGS+= -fstack-protector
223 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
225 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
226 ${MK_KERNEL_RETPOLINE} != "no"
231 # Initialize stack variables on function entry
233 .if ${MK_INIT_ALL_ZERO} == "yes"
234 .if ${COMPILER_FEATURES:Minit-all}
235 CFLAGS+= -ftrivial-auto-var-init=zero \
236 -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
238 .warning InitAll (zeros) requested but not support by compiler
240 .elif ${MK_INIT_ALL_PATTERN} == "yes"
241 .if ${COMPILER_FEATURES:Minit-all}
242 CFLAGS+= -ftrivial-auto-var-init=pattern
244 .warning InitAll (pattern) requested but not support by compiler
249 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
250 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
251 # cope well with DWARF 4, so force it to genereate DWARF2, which they
252 # understand. Do this unconditionally as it is harmless when not needed,
253 # but critical for these newer versions.
255 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
259 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
260 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
261 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
263 # Tell bmake not to mistake standard targets for things to be searched for
264 # or expect to ever be up-to-date.
265 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
266 beforelinking build build-tools buildfiles buildincludes \
267 checkdpadd clean cleandepend cleandir cleanobj configure \
268 depend distclean distribute exe \
269 html includes install installfiles installincludes \
270 obj objlink objs objwarn \
271 realinstall regress \
274 .PHONY: ${PHONY_NOTMAIN}
275 .NOTMAIN: ${PHONY_NOTMAIN}
280 CFLAGS+= -traditional
281 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
282 CFLAGS+= -std=iso9899:1990
283 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
284 CFLAGS+= -std=iso9899:199409
285 .elif ${CSTD} == "c99"
286 CFLAGS+= -std=iso9899:1999
288 CFLAGS+= -std=${CSTD}
291 # Please keep this if in sync with bsd.sys.mk
292 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
293 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
294 # Note: Clang 12+ will prefer --ld-path= over -fuse-ld=.
295 .if ${COMPILER_TYPE} == "clang"
296 # Note: unlike bsd.sys.mk we can't use LDFLAGS here since that is used for the
297 # flags required when linking the kernel. We don't need those flags when
298 # building the vdsos. However, we do need -fuse-ld, so use ${CCLDFLAGS} instead.
299 # Note: Clang does not like relative paths in -fuse-ld so we map ld.lld -> lld.
300 CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W}
302 # GCC does not support an absolute path for -fuse-ld so we just print this
303 # warning instead and let the user add the required symlinks.
304 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
308 # Set target-specific linker emulation name.
309 LD_EMULATION_aarch64=aarch64elf
310 LD_EMULATION_amd64=elf_x86_64_fbsd
311 LD_EMULATION_arm=armelf_fbsd
312 LD_EMULATION_armv6=armelf_fbsd
313 LD_EMULATION_armv7=armelf_fbsd
314 LD_EMULATION_i386=elf_i386_fbsd
315 LD_EMULATION_mips= elf32btsmip_fbsd
316 LD_EMULATION_mipshf= elf32btsmip_fbsd
317 LD_EMULATION_mips64= elf64btsmip_fbsd
318 LD_EMULATION_mips64hf= elf64btsmip_fbsd
319 LD_EMULATION_mipsel= elf32ltsmip_fbsd
320 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
321 LD_EMULATION_mips64el= elf64ltsmip_fbsd
322 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
323 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
324 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
325 LD_EMULATION_powerpc= elf32ppc_fbsd
326 LD_EMULATION_powerpcspe= elf32ppc_fbsd
327 LD_EMULATION_powerpc64= elf64ppc_fbsd
328 LD_EMULATION_powerpc64le= elf64lppc_fbsd
329 LD_EMULATION_riscv64= elf64lriscv
330 LD_EMULATION_riscv64sf= elf64lriscv
331 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}