sys/conf/kern.mk

   1 # $FreeBSD$
   2
   3 #
   4 # Warning flags for compiling the kernel and components of the kernel:
   5 #
   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 \
  11                 ${CWARNEXTRA}
  12 #
  13 # The following flags are next up for working on:
  14 #       -Wextra
  15
  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
  18 # a false positive.
  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 .if ${COMPILER_VERSION} >= 100000
  29 NO_WMISLEADING_INDENTATION=     -Wno-misleading-indentation
  30 .endif
  31 .if ${COMPILER_VERSION} >= 140000
  32 NO_WBITWISE_INSTEAD_OF_LOGICAL= -Wno-bitwise-instead-of-logical
  33 .endif
  34 .if ${COMPILER_VERSION} >= 150000
  35 NO_WSTRICT_PROTOTYPES=          -Wno-strict-prototypes
  36 .endif
  37 # Several other warnings which might be useful in some cases, but not severe
  38 # enough to error out the whole kernel build.  Display them anyway, so there is
  39 # some incentive to fix them eventually.
  40 CWARNEXTRA?=    -Wno-error=tautological-compare -Wno-error=empty-body \
  41                 -Wno-error=parentheses-equality -Wno-error=unused-function \
  42                 -Wno-error=pointer-sign
  43 CWARNEXTRA+=    -Wno-error=shift-negative-value
  44 CWARNEXTRA+=    -Wno-address-of-packed-member
  45 .if ${COMPILER_VERSION} >= 130000
  46 CWARNFLAGS+=    -Wno-error=unused-but-set-variable
  47 .endif
  48 .endif  # clang
  49
  50 .if ${COMPILER_TYPE} == "gcc"
  51 # Catch-all for all the things that are in our tree, but for which we're
  52 # not yet ready for this compiler.
  53 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  54 CWARNEXTRA?=    -Wno-error=address                              \
  55                 -Wno-error=aggressive-loop-optimizations        \
  56                 -Wno-error=array-bounds                         \
  57                 -Wno-error=attributes                           \
  58                 -Wno-error=cast-qual                            \
  59                 -Wno-error=enum-compare                         \
  60                 -Wno-error=maybe-uninitialized                  \
  61                 -Wno-error=misleading-indentation               \
  62                 -Wno-error=nonnull-compare                      \
  63                 -Wno-error=overflow                             \
  64                 -Wno-error=sequence-point                       \
  65                 -Wno-error=shift-overflow                       \
  66                 -Wno-error=tautological-compare                 \
  67                 -Wno-unused-but-set-variable
  68 .if ${COMPILER_VERSION} >= 70100
  69 CWARNEXTRA+=    -Wno-error=stringop-overflow
  70 .endif
  71 .if ${COMPILER_VERSION} >= 70200
  72 CWARNEXTRA+=    -Wno-error=memset-elt-size
  73 .endif
  74 .if ${COMPILER_VERSION} >= 80000
  75 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  76 .endif
  77 .if ${COMPILER_VERSION} >= 90100
  78 CWARNEXTRA+=    -Wno-address-of-packed-member                   \
  79                 -Wno-error=alloca-larger-than=
  80 .endif
  81
  82 # GCC produces false positives for functions that switch on an
  83 # enum (GCC bug 87950)
  84 CWARNFLAGS+=    -Wno-return-type
  85 .endif  # gcc
  86
  87 # This warning is utter nonsense
  88 CWARNFLAGS+=    -Wno-format-zero-length
  89
  90 # External compilers may not support our format extensions.  Allow them
  91 # to be disabled.  WARNING: format checking is disabled in this case.
  92 .if ${MK_FORMAT_EXTENSIONS} == "no"
  93 FORMAT_EXTENSIONS=      -Wno-format
  94 .elif ${COMPILER_TYPE} == "clang"
  95 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  96 .else
  97 FORMAT_EXTENSIONS=      -fformat-extensions
  98 .endif
  99
 100 #
 101 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 102 # and above adds code to the entry and exit point of every function to align the
 103 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 104 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 105 # it is probably an overall loss as it makes the code bigger (less efficient
 106 # use of code cache tag lines) and uses more stack (less efficient use of data
 107 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 108 # operations inside the kernel itself.  These operations are exclusively
 109 # reserved for user applications.
 110 #
 111 # gcc:
 112 # Setting -mno-mmx implies -mno-3dnow
 113 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 114 #
 115 # clang:
 116 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 117 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 118 #
 119 .if ${MACHINE_CPUARCH} == "i386"
 120 CFLAGS.gcc+=    -mpreferred-stack-boundary=2
 121 CFLAGS.clang+=  -mno-aes -mno-avx
 122 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 123 INLINE_LIMIT?=  8000
 124 .endif
 125
 126 .if ${MACHINE_CPUARCH} == "arm"
 127 INLINE_LIMIT?=  8000
 128 .endif
 129
 130 .if ${MACHINE_CPUARCH} == "aarch64"
 131 # We generally don't want fpu instructions in the kernel.
 132 CFLAGS += -mgeneral-regs-only
 133 # Reserve x18 for pcpu data
 134 CFLAGS += -ffixed-x18
 135 INLINE_LIMIT?=  8000
 136 .endif
 137
 138 #
 139 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 140 # point registers within the kernel. However, for kernels supporting hardware
 141 # float (FPE), we have to include that in the march so we can have limited
 142 # floating point support in context switching needed for that. This is different
 143 # than userland where we use a hard-float ABI (lp64d).
 144 #
 145 # We also specify the "medium" code model, which generates code suitable for a
 146 # 2GiB addressing range located at any offset, allowing modules to be located
 147 # anywhere in the 64-bit address space.  Note that clang and GCC refer to this
 148 # code model as "medium" and "medany" respectively.
 149 #
 150 .if ${MACHINE_CPUARCH} == "riscv"
 151 CFLAGS+=        -march=rv64imafdc
 152 CFLAGS+=        -mabi=lp64
 153 CFLAGS.clang+=  -mcmodel=medium
 154 CFLAGS.gcc+=    -mcmodel=medany
 155 INLINE_LIMIT?=  8000
 156
 157 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 158 CFLAGS+=        -mno-relax
 159 .endif
 160 .endif
 161
 162 #
 163 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 164 # operations inside the kernel itself.  These operations are exclusively
 165 # reserved for user applications.
 166 #
 167 # gcc:
 168 # Setting -mno-mmx implies -mno-3dnow
 169 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 170 #
 171 # clang:
 172 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 173 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 174 # (-mfpmath= is not supported)
 175 #
 176 .if ${MACHINE_CPUARCH} == "amd64"
 177 CFLAGS.clang+=  -mno-aes -mno-avx
 178 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 179                 -fno-asynchronous-unwind-tables
 180 INLINE_LIMIT?=  8000
 181 .endif
 182
 183 #
 184 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 185 # floating point registers for integer operations which it has a tendency to do.
 186 # Also explicitly disable Altivec instructions inside the kernel.
 187 #
 188 .if ${MACHINE_CPUARCH} == "powerpc"
 189 CFLAGS+=        -mno-altivec -msoft-float
 190 INLINE_LIMIT?=  15000
 191 .endif
 192
 193 .if ${MACHINE_ARCH} == "powerpcspe"
 194 CFLAGS.gcc+=    -mno-spe
 195 .endif
 196
 197 #
 198 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 199 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 200 #
 201 .if ${MACHINE_ARCH:Mpowerpc64*} != ""
 202 CFLAGS+=        -mabi=elfv2
 203 .endif
 204
 205 #
 206 # For MIPS we also tell gcc to use floating point emulation
 207 #
 208 .if ${MACHINE_CPUARCH} == "mips"
 209 CFLAGS+=        -msoft-float
 210 INLINE_LIMIT?=  8000
 211 .endif
 212
 213 #
 214 # GCC 3.0 and above like to do certain optimizations based on the
 215 # assumption that the program is linked against libc.  Stop this.
 216 #
 217 CFLAGS+=        -ffreestanding
 218
 219 #
 220 # The C standard leaves signed integer overflow behavior undefined.
 221 # gcc and clang opimizers take advantage of this.  The kernel makes
 222 # use of signed integer wraparound mechanics so we need the compiler
 223 # to treat it as a wraparound and not take shortcuts.
 224 #
 225 CFLAGS+=        -fwrapv
 226
 227 #
 228 # GCC SSP support
 229 #
 230 .if ${MK_SSP} != "no"
 231 CFLAGS+=        -fstack-protector
 232 .endif
 233
 234 #
 235 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 236 #
 237 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 238     ${MK_KERNEL_RETPOLINE} != "no"
 239 CFLAGS+=        -mretpoline
 240 .endif
 241
 242 #
 243 # Initialize stack variables on function entry
 244 #
 245 .if ${MK_INIT_ALL_ZERO} == "yes"
 246 .if ${COMPILER_FEATURES:Minit-all}
 247 CFLAGS+= -ftrivial-auto-var-init=zero \
 248     -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
 249 .else
 250 .warning InitAll (zeros) requested but not support by compiler
 251 .endif
 252 .elif ${MK_INIT_ALL_PATTERN} == "yes"
 253 .if ${COMPILER_FEATURES:Minit-all}
 254 CFLAGS+= -ftrivial-auto-var-init=pattern
 255 .else
 256 .warning InitAll (pattern) requested but not support by compiler
 257 .endif
 258 .endif
 259
 260 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 261 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 262 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 263
 264 # Tell bmake not to mistake standard targets for things to be searched for
 265 # or expect to ever be up-to-date.
 266 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 267                 beforelinking build build-tools buildfiles buildincludes \
 268                 checkdpadd clean cleandepend cleandir cleanobj configure \
 269                 depend distclean distribute exe \
 270                 html includes install installfiles installincludes \
 271                 obj objlink objs objwarn \
 272                 realinstall regress \
 273                 tags whereobj
 274
 275 .PHONY: ${PHONY_NOTMAIN}
 276 .NOTMAIN: ${PHONY_NOTMAIN}
 277
 278 CSTD=           c99
 279
 280 .if ${CSTD} == "k&r"
 281 CFLAGS+=        -traditional
 282 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 283 CFLAGS+=        -std=iso9899:1990
 284 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 285 CFLAGS+=        -std=iso9899:199409
 286 .elif ${CSTD} == "c99"
 287 CFLAGS+=        -std=iso9899:1999
 288 .else # CSTD
 289 CFLAGS+=        -std=${CSTD}
 290 .endif # CSTD
 291
 292 # Please keep this if in sync with bsd.sys.mk
 293 .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld")
 294 # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld".
 295 .if ${COMPILER_TYPE} == "clang"
 296 # Note: Clang does not like relative paths for ld so we map ld.lld -> lld.
 297 .if ${COMPILER_VERSION} >= 120000
 298 CCLDFLAGS+=     --ld-path=${LD:[1]:S/^ld.//1W}
 299 .else
 300 CCLDFLAGS+=     -fuse-ld=${LD:[1]:S/^ld.//1W}
 301 .endif
 302 .else
 303 # GCC does not support an absolute path for -fuse-ld so we just print this
 304 # warning instead and let the user add the required symlinks.
 305 # However, we can avoid this warning if -B is set appropriately (e.g. for
 306 # CROSS_TOOLCHAIN=...-gcc).
 307 .if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/})
 308 .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
 309 .endif
 310 .endif
 311 .endif
 312
 313 # Set target-specific linker emulation name.
 314 LD_EMULATION_aarch64=aarch64elf
 315 LD_EMULATION_amd64=elf_x86_64_fbsd
 316 LD_EMULATION_arm=armelf_fbsd
 317 LD_EMULATION_armv6=armelf_fbsd
 318 LD_EMULATION_armv7=armelf_fbsd
 319 LD_EMULATION_i386=elf_i386_fbsd
 320 LD_EMULATION_mips= elf32btsmip_fbsd
 321 LD_EMULATION_mipshf= elf32btsmip_fbsd
 322 LD_EMULATION_mips64= elf64btsmip_fbsd
 323 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 324 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 325 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 326 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 327 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 328 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 329 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 330 LD_EMULATION_powerpc= elf32ppc_fbsd
 331 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 332 LD_EMULATION_powerpc64= elf64ppc_fbsd
 333 LD_EMULATION_powerpc64le= elf64lppc_fbsd
 334 LD_EMULATION_riscv64= elf64lriscv
 335 LD_EMULATION_riscv64sf= elf64lriscv
 336 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}