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 # Several other warnings which might be useful in some cases, but not severe
  32 # enough to error out the whole kernel build.  Display them anyway, so there is
  33 # some incentive to fix them eventually.
  34 CWARNEXTRA?=    -Wno-error=tautological-compare -Wno-error=empty-body \
  35                 -Wno-error=parentheses-equality -Wno-error=unused-function \
  36                 -Wno-error=pointer-sign
  37 .if ${COMPILER_VERSION} >= 30700
  38 CWARNEXTRA+=    -Wno-error=shift-negative-value
  39 .endif
  40 .if ${COMPILER_VERSION} >= 40000
  41 CWARNEXTRA+=    -Wno-address-of-packed-member
  42 .endif
  43 .if ${COMPILER_VERSION} >= 130000
  44 CWARNFLAGS+=    -Wno-error=unused-but-set-variable
  45 .endif
  46 .endif  # clang
  47
  48 .if ${COMPILER_TYPE} == "gcc"
  49 .if ${COMPILER_VERSION} >= 40800
  50 # Catch-all for all the things that are in our tree, but for which we're
  51 # not yet ready for this compiler.
  52 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  53 CWARNEXTRA?=    -Wno-error=address                              \
  54                 -Wno-error=aggressive-loop-optimizations        \
  55                 -Wno-error=array-bounds                         \
  56                 -Wno-error=attributes                           \
  57                 -Wno-error=cast-qual                            \
  58                 -Wno-error=enum-compare                         \
  59                 -Wno-error=inline                               \
  60                 -Wno-error=maybe-uninitialized                  \
  61                 -Wno-error=overflow                             \
  62                 -Wno-error=sequence-point                       \
  63                 -Wno-error=unused-but-set-variable
  64 .if ${COMPILER_VERSION} >= 60100
  65 CWARNEXTRA+=    -Wno-error=misleading-indentation               \
  66                 -Wno-error=nonnull-compare                      \
  67                 -Wno-error=shift-overflow                       \
  68                 -Wno-error=tautological-compare
  69 .endif
  70 .if ${COMPILER_VERSION} >= 70200
  71 CWARNEXTRA+=    -Wno-error=memset-elt-size
  72 .endif
  73 .if ${COMPILER_VERSION} >= 80000
  74 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  75 .endif
  76 .else
  77 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  78 CWARNEXTRA?=    -Wno-uninitialized
  79 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
  80 # the few files that are already known to generate cast-qual warnings.
  81 NO_WCAST_QUAL= -Wno-cast-qual
  82 .endif
  83 .endif
  84
  85 # This warning is utter nonsense
  86 CWARNFLAGS+=    -Wno-format-zero-length
  87
  88 # External compilers may not support our format extensions.  Allow them
  89 # to be disabled.  WARNING: format checking is disabled in this case.
  90 .if ${MK_FORMAT_EXTENSIONS} == "no"
  91 FORMAT_EXTENSIONS=      -Wno-format
  92 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  93 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  94 .else
  95 FORMAT_EXTENSIONS=      -fformat-extensions
  96 .endif
  97
  98 #
  99 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 100 # and above adds code to the entry and exit point of every function to align the
 101 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 102 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 103 # it is probably an overall loss as it makes the code bigger (less efficient
 104 # use of code cache tag lines) and uses more stack (less efficient use of data
 105 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 106 # operations inside the kernel itself.  These operations are exclusively
 107 # reserved for user applications.
 108 #
 109 # gcc:
 110 # Setting -mno-mmx implies -mno-3dnow
 111 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 112 #
 113 # clang:
 114 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 115 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 116 #
 117 .if ${MACHINE_CPUARCH} == "i386"
 118 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 119 CFLAGS.clang+=  -mno-aes -mno-avx
 120 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 121 INLINE_LIMIT?=  8000
 122 .endif
 123
 124 .if ${MACHINE_CPUARCH} == "arm"
 125 INLINE_LIMIT?=  8000
 126 .endif
 127
 128 .if ${MACHINE_CPUARCH} == "aarch64"
 129 # We generally don't want fpu instructions in the kernel.
 130 CFLAGS += -mgeneral-regs-only
 131 # Reserve x18 for pcpu data
 132 CFLAGS += -ffixed-x18
 133 INLINE_LIMIT?=  8000
 134 .endif
 135
 136 #
 137 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 138 # point registers within the kernel. We also specify the "medium" code model,
 139 # which generates code suitable for a 2GiB addressing range located at any
 140 # offset, allowing modules to be located anywhere in the 64-bit address space.
 141 # Note that clang and GCC refer to this code model as "medium" and "medany"
 142 # respectively.
 143 #
 144 .if ${MACHINE_CPUARCH} == "riscv"
 145 CFLAGS+=        -march=rv64imafdc -mabi=lp64
 146 CFLAGS.clang+=  -mcmodel=medium
 147 CFLAGS.gcc+=    -mcmodel=medany
 148 INLINE_LIMIT?=  8000
 149
 150 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 151 CFLAGS+=        -mno-relax
 152 .endif
 153 .endif
 154
 155 #
 156 # For sparc64 we want the medany code model so modules may be located
 157 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 158 # point emulation.  This avoids using floating point registers for integer
 159 # operations which it has a tendency to do.
 160 #
 161 .if ${MACHINE_CPUARCH} == "sparc64"
 162 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 163 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 164 INLINE_LIMIT?=  15000
 165 .endif
 166
 167 #
 168 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 169 # operations inside the kernel itself.  These operations are exclusively
 170 # reserved for user applications.
 171 #
 172 # gcc:
 173 # Setting -mno-mmx implies -mno-3dnow
 174 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 175 #
 176 # clang:
 177 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 178 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 179 # (-mfpmath= is not supported)
 180 #
 181 .if ${MACHINE_CPUARCH} == "amd64"
 182 CFLAGS.clang+=  -mno-aes -mno-avx
 183 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 184                 -fno-asynchronous-unwind-tables
 185 INLINE_LIMIT?=  8000
 186 .endif
 187
 188 #
 189 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 190 # floating point registers for integer operations which it has a tendency to do.
 191 # Also explicitly disable Altivec instructions inside the kernel.
 192 #
 193 .if ${MACHINE_CPUARCH} == "powerpc"
 194 CFLAGS+=        -mno-altivec -msoft-float
 195 INLINE_LIMIT?=  15000
 196 .endif
 197
 198 .if ${MACHINE_ARCH} == "powerpcspe"
 199 CFLAGS.gcc+=    -mno-spe
 200 .endif
 201
 202 #
 203 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 204 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 205 #
 206 .if ${MACHINE_ARCH} == "powerpc64"
 207 .if ${COMPILER_VERSION} >= 40900
 208 CFLAGS.gcc+=    -mabi=elfv2
 209 .else
 210 CFLAGS.gcc+=    -mcall-aixdesc
 211 .endif
 212 CFLAGS.clang+=  -mabi=elfv2
 213 .endif
 214
 215 #
 216 # For MIPS we also tell gcc to use floating point emulation
 217 #
 218 .if ${MACHINE_CPUARCH} == "mips"
 219 CFLAGS+=        -msoft-float
 220 INLINE_LIMIT?=  8000
 221 .endif
 222
 223 #
 224 # GCC 3.0 and above like to do certain optimizations based on the
 225 # assumption that the program is linked against libc.  Stop this.
 226 #
 227 CFLAGS+=        -ffreestanding
 228
 229 #
 230 # The C standard leaves signed integer overflow behavior undefined.
 231 # gcc and clang opimizers take advantage of this.  The kernel makes
 232 # use of signed integer wraparound mechanics so we need the compiler
 233 # to treat it as a wraparound and not take shortcuts.
 234 #
 235 CFLAGS+=        -fwrapv
 236
 237 #
 238 # GCC SSP support
 239 #
 240 .if ${MK_SSP} != "no" && \
 241     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 242 CFLAGS+=        -fstack-protector
 243 .endif
 244
 245 #
 246 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 247 #
 248 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 249     ${MK_KERNEL_RETPOLINE} != "no"
 250 CFLAGS+=        -mretpoline
 251 .endif
 252
 253 #
 254 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 255 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 256 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 257 # understand. Do this unconditionally as it is harmless when not needed,
 258 # but critical for these newer versions.
 259 #
 260 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 261 CFLAGS+=        -gdwarf-2
 262 .endif
 263
 264 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 265 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 266
 267 # Tell bmake not to mistake standard targets for things to be searched for
 268 # or expect to ever be up-to-date.
 269 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 270                 beforelinking build build-tools buildfiles buildincludes \
 271                 checkdpadd clean cleandepend cleandir cleanobj configure \
 272                 depend distclean distribute exe \
 273                 html includes install installfiles installincludes \
 274                 obj objlink objs objwarn \
 275                 realinstall regress \
 276                 tags whereobj
 277
 278 .PHONY: ${PHONY_NOTMAIN}
 279 .NOTMAIN: ${PHONY_NOTMAIN}
 280
 281 CSTD=           c99
 282
 283 .if ${CSTD} == "k&r"
 284 CFLAGS+=        -traditional
 285 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 286 CFLAGS+=        -std=iso9899:1990
 287 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 288 CFLAGS+=        -std=iso9899:199409
 289 .elif ${CSTD} == "c99"
 290 CFLAGS+=        -std=iso9899:1999
 291 .else # CSTD
 292 CFLAGS+=        -std=${CSTD}
 293 .endif # CSTD
 294
 295 # Set target-specific linker emulation name.
 296 LD_EMULATION_aarch64=aarch64elf
 297 LD_EMULATION_amd64=elf_x86_64_fbsd
 298 LD_EMULATION_arm=armelf_fbsd
 299 LD_EMULATION_armv6=armelf_fbsd
 300 LD_EMULATION_armv7=armelf_fbsd
 301 LD_EMULATION_i386=elf_i386_fbsd
 302 LD_EMULATION_mips= elf32btsmip_fbsd
 303 LD_EMULATION_mipshf= elf32btsmip_fbsd
 304 LD_EMULATION_mips64= elf64btsmip_fbsd
 305 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 306 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 307 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 308 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 309 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 310 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 311 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 312 LD_EMULATION_powerpc= elf32ppc_fbsd
 313 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 314 LD_EMULATION_powerpc64= elf64ppc_fbsd
 315 LD_EMULATION_riscv64= elf64lriscv
 316 LD_EMULATION_sparc64= elf64_sparc_fbsd
 317 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}