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} >= 70200
  65 CWARNEXTRA+=    -Wno-error=memset-elt-size
  66 .endif
  67 .if ${COMPILER_VERSION} >= 80000
  68 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  69 .endif
  70 .else
  71 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  72 CWARNEXTRA?=    -Wno-uninitialized
  73 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
  74 # the few files that are already known to generate cast-qual warnings.
  75 NO_WCAST_QUAL= -Wno-cast-qual
  76 NO_WNONNULL=    -Wno-nonnull
  77 .endif
  78 .endif
  79
  80 # This warning is utter nonsense
  81 CWARNFLAGS+=    -Wno-format-zero-length
  82
  83 # External compilers may not support our format extensions.  Allow them
  84 # to be disabled.  WARNING: format checking is disabled in this case.
  85 .if ${MK_FORMAT_EXTENSIONS} == "no"
  86 FORMAT_EXTENSIONS=      -Wno-format
  87 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  88 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  89 .else
  90 FORMAT_EXTENSIONS=      -fformat-extensions
  91 .endif
  92
  93 #
  94 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  95 # and above adds code to the entry and exit point of every function to align the
  96 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
  97 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
  98 # it is probably an overall loss as it makes the code bigger (less efficient
  99 # use of code cache tag lines) and uses more stack (less efficient use of data
 100 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 101 # operations inside the kernel itself.  These operations are exclusively
 102 # reserved for user applications.
 103 #
 104 # gcc:
 105 # Setting -mno-mmx implies -mno-3dnow
 106 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 107 #
 108 # clang:
 109 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 110 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 111 #
 112 .if ${MACHINE_CPUARCH} == "i386"
 113 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 114 CFLAGS.clang+=  -mno-aes -mno-avx
 115 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 116 INLINE_LIMIT?=  8000
 117 .endif
 118
 119 .if ${MACHINE_CPUARCH} == "arm"
 120 INLINE_LIMIT?=  8000
 121 .endif
 122
 123 .if ${MACHINE_CPUARCH} == "aarch64"
 124 # We generally don't want fpu instructions in the kernel.
 125 CFLAGS += -mgeneral-regs-only
 126 # Reserve x18 for pcpu data
 127 CFLAGS += -ffixed-x18
 128 INLINE_LIMIT?=  8000
 129 .endif
 130
 131 #
 132 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 133 # point registers within the kernel. We also specify the "medium" code model,
 134 # which generates code suitable for a 2GiB addressing range located at any
 135 # offset, allowing modules to be located anywhere in the 64-bit address space.
 136 # Note that clang and GCC refer to this code model as "medium" and "medany"
 137 # respectively.
 138 #
 139 .if ${MACHINE_CPUARCH} == "riscv"
 140 CFLAGS+=        -march=rv64imafdc -mabi=lp64
 141 CFLAGS.clang+=  -mcmodel=medium
 142 CFLAGS.gcc+=    -mcmodel=medany
 143 INLINE_LIMIT?=  8000
 144 .endif
 145
 146 #
 147 # For sparc64 we want the medany code model so modules may be located
 148 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 149 # point emulation.  This avoids using floating point registers for integer
 150 # operations which it has a tendency to do.
 151 #
 152 .if ${MACHINE_CPUARCH} == "sparc64"
 153 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 154 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 155 INLINE_LIMIT?=  15000
 156 .endif
 157
 158 #
 159 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 160 # operations inside the kernel itself.  These operations are exclusively
 161 # reserved for user applications.
 162 #
 163 # gcc:
 164 # Setting -mno-mmx implies -mno-3dnow
 165 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 166 #
 167 # clang:
 168 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 169 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 170 # (-mfpmath= is not supported)
 171 #
 172 .if ${MACHINE_CPUARCH} == "amd64"
 173 CFLAGS.clang+=  -mno-aes -mno-avx
 174 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 175                 -fno-asynchronous-unwind-tables
 176 INLINE_LIMIT?=  8000
 177 .endif
 178
 179 #
 180 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 181 # floating point registers for integer operations which it has a tendency to do.
 182 # Also explicitly disable Altivec instructions inside the kernel.
 183 #
 184 .if ${MACHINE_CPUARCH} == "powerpc"
 185 CFLAGS+=        -mno-altivec -msoft-float
 186 INLINE_LIMIT?=  15000
 187 .endif
 188
 189 .if ${MACHINE_ARCH} == "powerpcspe"
 190 CFLAGS.gcc+=    -mno-spe
 191 .endif
 192
 193 #
 194 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 195 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 196 #
 197 .if ${MACHINE_ARCH} == "powerpc64"
 198 .if ${COMPILER_VERSION} >= 40900
 199 CFLAGS.gcc+=    -mabi=elfv2
 200 .else
 201 CFLAGS.gcc+=    -mcall-aixdesc
 202 .endif
 203 CFLAGS.clang+=  -mabi=elfv2
 204 .endif
 205
 206 #
 207 # For MIPS we also tell gcc to use floating point emulation
 208 #
 209 .if ${MACHINE_CPUARCH} == "mips"
 210 CFLAGS+=        -msoft-float
 211 INLINE_LIMIT?=  8000
 212 .endif
 213
 214 #
 215 # GCC 3.0 and above like to do certain optimizations based on the
 216 # assumption that the program is linked against libc.  Stop this.
 217 #
 218 CFLAGS+=        -ffreestanding
 219
 220 #
 221 # The C standard leaves signed integer overflow behavior undefined.
 222 # gcc and clang opimizers take advantage of this.  The kernel makes
 223 # use of signed integer wraparound mechanics so we need the compiler
 224 # to treat it as a wraparound and not take shortcuts.
 225 #
 226 CFLAGS+=        -fwrapv
 227
 228 #
 229 # GCC SSP support
 230 #
 231 .if ${MK_SSP} != "no" && \
 232     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 233 CFLAGS+=        -fstack-protector
 234 .endif
 235
 236 #
 237 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 238 #
 239 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 240     ${MK_KERNEL_RETPOLINE} != "no"
 241 CFLAGS+=        -mretpoline
 242 .endif
 243
 244 #
 245 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 246 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 247 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 248 # understand. Do this unconditionally as it is harmless when not needed,
 249 # but critical for these newer versions.
 250 #
 251 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 252 CFLAGS+=        -gdwarf-2
 253 .endif
 254
 255 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 256 CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}}
 257 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 258
 259 # Tell bmake not to mistake standard targets for things to be searched for
 260 # or expect to ever be up-to-date.
 261 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 262                 beforelinking build build-tools buildfiles buildincludes \
 263                 checkdpadd clean cleandepend cleandir cleanobj configure \
 264                 depend distclean distribute exe \
 265                 html includes install installfiles installincludes \
 266                 obj objlink objs objwarn \
 267                 realinstall regress \
 268                 tags whereobj
 269
 270 .PHONY: ${PHONY_NOTMAIN}
 271 .NOTMAIN: ${PHONY_NOTMAIN}
 272
 273 CSTD=           c99
 274
 275 .if ${CSTD} == "k&r"
 276 CFLAGS+=        -traditional
 277 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 278 CFLAGS+=        -std=iso9899:1990
 279 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 280 CFLAGS+=        -std=iso9899:199409
 281 .elif ${CSTD} == "c99"
 282 CFLAGS+=        -std=iso9899:1999
 283 .else # CSTD
 284 CFLAGS+=        -std=${CSTD}
 285 .endif # CSTD
 286
 287 # Set target-specific linker emulation name.
 288 LD_EMULATION_aarch64=aarch64elf
 289 LD_EMULATION_amd64=elf_x86_64_fbsd
 290 LD_EMULATION_arm=armelf_fbsd
 291 LD_EMULATION_armv6=armelf_fbsd
 292 LD_EMULATION_armv7=armelf_fbsd
 293 LD_EMULATION_i386=elf_i386_fbsd
 294 LD_EMULATION_mips= elf32btsmip_fbsd
 295 LD_EMULATION_mipshf= elf32btsmip_fbsd
 296 LD_EMULATION_mips64= elf64btsmip_fbsd
 297 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 298 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 299 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 300 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 301 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 302 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 303 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 304 LD_EMULATION_powerpc= elf32ppc_fbsd
 305 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 306 LD_EMULATION_powerpc64= elf64ppc_fbsd
 307 LD_EMULATION_riscv64= elf64lriscv
 308 LD_EMULATION_sparc64= elf64_sparc_fbsd
 309 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}