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