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 .if ${COMPILER_VERSION} >= 30700
  35 CWARNEXTRA+=    -Wno-error-shift-negative-value
  36 .endif
  37 .if ${COMPILER_VERSION} >= 40000
  38 CWARNEXTRA+=    -Wno-address-of-packed-member
  39 .endif
  40 .endif
  41
  42 .if ${COMPILER_TYPE} == "gcc"
  43 .if ${COMPILER_VERSION} >= 40800
  44 # Catch-all for all the things that are in our tree, but for which we're
  45 # not yet ready for this compiler.
  46 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  47 CWARNEXTRA?=    -Wno-error=address                              \
  48                 -Wno-error=aggressive-loop-optimizations        \
  49                 -Wno-error=array-bounds                         \
  50                 -Wno-error=attributes                           \
  51                 -Wno-error=cast-qual                            \
  52                 -Wno-error=enum-compare                         \
  53                 -Wno-error=inline                               \
  54                 -Wno-error=maybe-uninitialized                  \
  55                 -Wno-error=overflow                             \
  56                 -Wno-error=sequence-point                       \
  57                 -Wno-unused-but-set-variable
  58 .if ${COMPILER_VERSION} >= 60100
  59 CWARNEXTRA+=    -Wno-error=misleading-indentation               \
  60                 -Wno-error=nonnull-compare                      \
  61                 -Wno-error=shift-overflow                       \
  62                 -Wno-error=tautological-compare
  63 .endif
  64 .if ${COMPILER_VERSION} >= 70100
  65 CWARNEXTRA+=    -Wno-error=stringop-overflow
  66 .endif
  67 .if ${COMPILER_VERSION} >= 70200
  68 CWARNEXTRA+=    -Wno-error=memset-elt-size
  69 .endif
  70 .if ${COMPILER_VERSION} >= 80000
  71 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  72 .endif
  73 .else
  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
  80 .endif
  81 .endif
  82
  83 # This warning is utter nonsense
  84 CWARNFLAGS+=    -Wno-format-zero-length
  85
  86 # External compilers may not support our format extensions.  Allow them
  87 # to be disabled.  WARNING: format checking is disabled in this case.
  88 .if ${MK_FORMAT_EXTENSIONS} == "no"
  89 FORMAT_EXTENSIONS=      -Wno-format
  90 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  91 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  92 .else
  93 FORMAT_EXTENSIONS=      -fformat-extensions
  94 .endif
  95
  96 #
  97 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  98 # and above adds code to the entry and exit point of every function to align the
  99 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 100 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 101 # it is probably an overall loss as it makes the code bigger (less efficient
 102 # use of code cache tag lines) and uses more stack (less efficient use of data
 103 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 104 # operations inside the kernel itself.  These operations are exclusively
 105 # reserved for user applications.
 106 #
 107 # gcc:
 108 # Setting -mno-mmx implies -mno-3dnow
 109 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 110 #
 111 # clang:
 112 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 113 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 114 #
 115 .if ${MACHINE_CPUARCH} == "i386"
 116 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 117 CFLAGS.clang+=  -mno-aes -mno-avx
 118 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 119 INLINE_LIMIT?=  8000
 120 .endif
 121
 122 .if ${MACHINE_CPUARCH} == "arm"
 123 INLINE_LIMIT?=  8000
 124 .endif
 125
 126 .if ${MACHINE_CPUARCH} == "aarch64"
 127 # We generally don't want fpu instructions in the kernel.
 128 CFLAGS += -mgeneral-regs-only
 129 # Reserve x18 for pcpu data
 130 CFLAGS += -ffixed-x18
 131 INLINE_LIMIT?=  8000
 132 .endif
 133
 134 #
 135 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 136 # point registers within the kernel. We also specify the "medium" code model,
 137 # which generates code suitable for a 2GiB addressing range located at any
 138 # offset, allowing modules to be located anywhere in the 64-bit address space.
 139 # Note that clang and GCC refer to this code model as "medium" and "medany"
 140 # respectively.
 141 #
 142 .if ${MACHINE_CPUARCH} == "riscv"
 143 CFLAGS+=        -march=rv64imafdc -mabi=lp64
 144 CFLAGS.clang+=  -mcmodel=medium
 145 CFLAGS.gcc+=    -mcmodel=medany
 146 INLINE_LIMIT?=  8000
 147
 148 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 149 CFLAGS+=        -mno-relax
 150 .endif
 151 .endif
 152
 153 #
 154 # For sparc64 we want the medany code model so modules may be located
 155 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 156 # point emulation.  This avoids using floating point registers for integer
 157 # operations which it has a tendency to do.
 158 #
 159 .if ${MACHINE_CPUARCH} == "sparc64"
 160 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 161 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 162 INLINE_LIMIT?=  15000
 163 .endif
 164
 165 #
 166 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 167 # operations inside the kernel itself.  These operations are exclusively
 168 # reserved for user applications.
 169 #
 170 # gcc:
 171 # Setting -mno-mmx implies -mno-3dnow
 172 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 173 #
 174 # clang:
 175 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 176 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 177 # (-mfpmath= is not supported)
 178 #
 179 .if ${MACHINE_CPUARCH} == "amd64"
 180 CFLAGS.clang+=  -mno-aes -mno-avx
 181 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 182                 -fno-asynchronous-unwind-tables
 183 INLINE_LIMIT?=  8000
 184 .endif
 185
 186 #
 187 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 188 # floating point registers for integer operations which it has a tendency to do.
 189 # Also explicitly disable Altivec instructions inside the kernel.
 190 #
 191 .if ${MACHINE_CPUARCH} == "powerpc"
 192 CFLAGS+=        -mno-altivec -msoft-float
 193 INLINE_LIMIT?=  15000
 194 .endif
 195
 196 .if ${MACHINE_ARCH} == "powerpcspe"
 197 CFLAGS.gcc+=    -mno-spe
 198 .endif
 199
 200 #
 201 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 202 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 203 #
 204 .if ${MACHINE_ARCH} == "powerpc64"
 205 .if ${COMPILER_VERSION} >= 40900
 206 CFLAGS.gcc+=    -mabi=elfv2
 207 .else
 208 CFLAGS.gcc+=    -mcall-aixdesc
 209 .endif
 210 CFLAGS.clang+=  -mabi=elfv2
 211 .endif
 212
 213 #
 214 # For MIPS we also tell gcc to use floating point emulation
 215 #
 216 .if ${MACHINE_CPUARCH} == "mips"
 217 CFLAGS+=        -msoft-float
 218 INLINE_LIMIT?=  8000
 219 .endif
 220
 221 #
 222 # GCC 3.0 and above like to do certain optimizations based on the
 223 # assumption that the program is linked against libc.  Stop this.
 224 #
 225 CFLAGS+=        -ffreestanding
 226
 227 #
 228 # The C standard leaves signed integer overflow behavior undefined.
 229 # gcc and clang opimizers take advantage of this.  The kernel makes
 230 # use of signed integer wraparound mechanics so we need the compiler
 231 # to treat it as a wraparound and not take shortcuts.
 232 #
 233 CFLAGS+=        -fwrapv
 234
 235 #
 236 # GCC SSP support
 237 #
 238 .if ${MK_SSP} != "no" && \
 239     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 240 CFLAGS+=        -fstack-protector
 241 .endif
 242
 243 #
 244 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 245 #
 246 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 247     ${MK_KERNEL_RETPOLINE} != "no"
 248 CFLAGS+=        -mretpoline
 249 .endif
 250
 251 #
 252 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 253 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 254 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 255 # understand. Do this unconditionally as it is harmless when not needed,
 256 # but critical for these newer versions.
 257 #
 258 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 259 CFLAGS+=        -gdwarf-2
 260 .endif
 261
 262 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 263 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 264 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 265
 266 # Tell bmake not to mistake standard targets for things to be searched for
 267 # or expect to ever be up-to-date.
 268 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 269                 beforelinking build build-tools buildfiles buildincludes \
 270                 checkdpadd clean cleandepend cleandir cleanobj configure \
 271                 depend distclean distribute exe \
 272                 html includes install installfiles installincludes \
 273                 obj objlink objs objwarn \
 274                 realinstall regress \
 275                 tags whereobj
 276
 277 .PHONY: ${PHONY_NOTMAIN}
 278 .NOTMAIN: ${PHONY_NOTMAIN}
 279
 280 CSTD=           c99
 281
 282 .if ${CSTD} == "k&r"
 283 CFLAGS+=        -traditional
 284 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 285 CFLAGS+=        -std=iso9899:1990
 286 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 287 CFLAGS+=        -std=iso9899:199409
 288 .elif ${CSTD} == "c99"
 289 CFLAGS+=        -std=iso9899:1999
 290 .else # CSTD
 291 CFLAGS+=        -std=${CSTD}
 292 .endif # CSTD
 293
 294 # Set target-specific linker emulation name.
 295 LD_EMULATION_aarch64=aarch64elf
 296 LD_EMULATION_amd64=elf_x86_64_fbsd
 297 LD_EMULATION_arm=armelf_fbsd
 298 LD_EMULATION_armv6=armelf_fbsd
 299 LD_EMULATION_armv7=armelf_fbsd
 300 LD_EMULATION_i386=elf_i386_fbsd
 301 LD_EMULATION_mips= elf32btsmip_fbsd
 302 LD_EMULATION_mipshf= elf32btsmip_fbsd
 303 LD_EMULATION_mips64= elf64btsmip_fbsd
 304 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 305 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 306 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 307 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 308 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 309 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 310 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 311 LD_EMULATION_powerpc= elf32ppc_fbsd
 312 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 313 LD_EMULATION_powerpc64= elf64ppc_fbsd
 314 LD_EMULATION_riscv64= elf64lriscv
 315 LD_EMULATION_sparc64= elf64_sparc_fbsd
 316 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}