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