sys/conf/kern.mk

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