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-error-shift-count-negative
  22 NO_WSHIFT_COUNT_OVERFLOW=       -Wno-error-shift-count-overflow
  23 NO_WSELF_ASSIGN=                -Wno-error-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 # Several other warnings which might be useful in some cases, but not severe
  28 # enough to error out the whole kernel build.  Display them anyway, so there is
  29 # some incentive to fix them eventually.
  30 CWARNEXTRA?=    -Wno-error-tautological-compare -Wno-error-empty-body \
  31                 -Wno-error-parentheses-equality -Wno-error-unused-function \
  32                 -Wno-error-pointer-sign
  33 .if ${COMPILER_VERSION} >= 30700
  34 CWARNEXTRA+=    -Wno-error-shift-negative-value
  35 .endif
  36 .if ${COMPILER_VERSION} >= 40000
  37 CWARNEXTRA+=    -Wno-error-address-of-packed-member
  38 .endif
  39
  40 CLANG_NO_IAS= -no-integrated-as
  41 .if ${COMPILER_VERSION} < 30500
  42 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
  43 CLANG_NO_IAS34= -no-integrated-as
  44 .endif
  45 .endif
  46
  47 .if ${COMPILER_TYPE} == "gcc"
  48 .if ${COMPILER_VERSION} >= 40800
  49 # Catch-all for all the things that are in our tree, but for which we're
  50 # not yet ready for this compiler.
  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=inline                               \
  58                 -Wno-error=maybe-uninitialized                  \
  59                 -Wno-error=overflow                             \
  60                 -Wno-error=sequence-point                       \
  61                 -Wno-error=unused-but-set-variable
  62 .if ${COMPILER_VERSION} >= 60100
  63 CWARNEXTRA+=    -Wno-error=misleading-indentation               \
  64                 -Wno-error=nonnull-compare                      \
  65                 -Wno-error=shift-overflow                       \
  66                 -Wno-error=tautological-compare
  67 .endif
  68 .if ${COMPILER_VERSION} >= 80000
  69 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  70 .endif
  71 .else
  72 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  73 CWARNEXTRA?=    -Wno-uninitialized
  74 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
  75 # the few files that are already known to generate cast-qual warnings.
  76 NO_WCAST_QUAL= -Wno-cast-qual
  77 .endif
  78 .endif
  79
  80 # External compilers may not support our format extensions.  Allow them
  81 # to be disabled.  WARNING: format checking is disabled in this case.
  82 .if ${MK_FORMAT_EXTENSIONS} == "no"
  83 FORMAT_EXTENSIONS=      -Wno-format
  84 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  85 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  86 .else
  87 FORMAT_EXTENSIONS=      -fformat-extensions
  88 .endif
  89
  90 #
  91 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  92 # and above adds code to the entry and exit point of every function to align the
  93 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
  94 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
  95 # it is probably an overall loss as it makes the code bigger (less efficient
  96 # use of code cache tag lines) and uses more stack (less efficient use of data
  97 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
  98 # operations inside the kernel itself.  These operations are exclusively
  99 # reserved for user applications.
 100 #
 101 # gcc:
 102 # Setting -mno-mmx implies -mno-3dnow
 103 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 104 #
 105 # clang:
 106 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 107 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 108 #
 109 .if ${MACHINE_CPUARCH} == "i386"
 110 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 111 CFLAGS.clang+=  -mno-aes -mno-avx
 112 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 113 INLINE_LIMIT?=  8000
 114 .endif
 115
 116 .if ${MACHINE_CPUARCH} == "arm"
 117 INLINE_LIMIT?=  8000
 118 .endif
 119
 120 .if ${MACHINE_CPUARCH} == "aarch64"
 121 # We generally don't want fpu instructions in the kernel.
 122 CFLAGS += -mgeneral-regs-only
 123 # Reserve x18 for pcpu data
 124 CFLAGS += -ffixed-x18
 125 INLINE_LIMIT?=  8000
 126 .endif
 127
 128 .if ${MACHINE_CPUARCH} == "riscv"
 129 CFLAGS.gcc+=    -mcmodel=medany -march=rv64imafdc -mabi=lp64
 130 INLINE_LIMIT?=  8000
 131 .endif
 132
 133 #
 134 # For sparc64 we want the medany code model so modules may be located
 135 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 136 # point emulation.  This avoids using floating point registers for integer
 137 # operations which it has a tendency to do.
 138 #
 139 .if ${MACHINE_CPUARCH} == "sparc64"
 140 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 141 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 142 INLINE_LIMIT?=  15000
 143 .endif
 144
 145 #
 146 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 147 # operations inside the kernel itself.  These operations are exclusively
 148 # reserved for user applications.
 149 #
 150 # gcc:
 151 # Setting -mno-mmx implies -mno-3dnow
 152 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 153 #
 154 # clang:
 155 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 156 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 157 # (-mfpmath= is not supported)
 158 #
 159 .if ${MACHINE_CPUARCH} == "amd64"
 160 CFLAGS.clang+=  -mno-aes -mno-avx
 161 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 162                 -fno-asynchronous-unwind-tables
 163 INLINE_LIMIT?=  8000
 164 .endif
 165
 166 #
 167 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 168 # floating point registers for integer operations which it has a tendency to do.
 169 # Also explicitly disable Altivec instructions inside the kernel.
 170 #
 171 .if ${MACHINE_CPUARCH} == "powerpc"
 172 CFLAGS+=        -mno-altivec -msoft-float
 173 INLINE_LIMIT?=  15000
 174 .endif
 175
 176 .if ${MACHINE_ARCH} == "powerpcspe"
 177 CFLAGS.gcc+=    -mno-spe
 178 .endif
 179
 180 #
 181 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 182 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 183 #
 184 .if ${MACHINE_ARCH} == "powerpc64"
 185 .if ${COMPILER_VERSION} >= 40900
 186 CFLAGS.gcc+=    -mabi=elfv2
 187 .else
 188 CFLAGS.gcc+=    -mcall-aixdesc
 189 .endif
 190 CFLAGS.clang+=  -mabi=elfv2
 191 .endif
 192
 193 #
 194 # For MIPS we also tell gcc to use floating point emulation
 195 #
 196 .if ${MACHINE_CPUARCH} == "mips"
 197 CFLAGS+=        -msoft-float
 198 INLINE_LIMIT?=  8000
 199 .endif
 200
 201 #
 202 # GCC 3.0 and above like to do certain optimizations based on the
 203 # assumption that the program is linked against libc.  Stop this.
 204 #
 205 CFLAGS+=        -ffreestanding
 206
 207 #
 208 # The C standard leaves signed integer overflow behavior undefined.
 209 # gcc and clang opimizers take advantage of this.  The kernel makes
 210 # use of signed integer wraparound mechanics so we need the compiler
 211 # to treat it as a wraparound and not take shortcuts.
 212 #
 213 CFLAGS+=        -fwrapv
 214
 215 #
 216 # GCC SSP support
 217 #
 218 .if ${MK_SSP} != "no" && \
 219     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 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 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 233 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 234 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 235 # understand. Do this unconditionally as it is harmless when not needed,
 236 # but critical for these newer versions.
 237 #
 238 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 239 CFLAGS+=        -gdwarf-2
 240 .endif
 241
 242 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 243 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 244
 245 # Tell bmake not to mistake standard targets for things to be searched for
 246 # or expect to ever be up-to-date.
 247 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 248                 beforelinking build build-tools buildfiles buildincludes \
 249                 checkdpadd clean cleandepend cleandir cleanobj configure \
 250                 depend distclean distribute exe \
 251                 html includes install installfiles installincludes \
 252                 obj objlink objs objwarn \
 253                 realinstall regress \
 254                 tags whereobj
 255
 256 .PHONY: ${PHONY_NOTMAIN}
 257 .NOTMAIN: ${PHONY_NOTMAIN}
 258
 259 CSTD=           c99
 260
 261 .if ${CSTD} == "k&r"
 262 CFLAGS+=        -traditional
 263 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 264 CFLAGS+=        -std=iso9899:1990
 265 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 266 CFLAGS+=        -std=iso9899:199409
 267 .elif ${CSTD} == "c99"
 268 CFLAGS+=        -std=iso9899:1999
 269 .else # CSTD
 270 CFLAGS+=        -std=${CSTD}
 271 .endif # CSTD
 272
 273 # Set target-specific linker emulation name.
 274 LD_EMULATION_aarch64=aarch64elf
 275 LD_EMULATION_amd64=elf_x86_64_fbsd
 276 LD_EMULATION_arm=armelf_fbsd
 277 LD_EMULATION_armeb=armelfb_fbsd
 278 LD_EMULATION_armv6=armelf_fbsd
 279 LD_EMULATION_armv7=armelf_fbsd
 280 LD_EMULATION_i386=elf_i386_fbsd
 281 LD_EMULATION_mips= elf32btsmip_fbsd
 282 LD_EMULATION_mipshf= elf32btsmip_fbsd
 283 LD_EMULATION_mips64= elf64btsmip_fbsd
 284 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 285 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 286 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 287 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 288 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 289 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 290 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 291 LD_EMULATION_powerpc= elf32ppc_fbsd
 292 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 293 LD_EMULATION_powerpc64= elf64ppc_fbsd
 294 LD_EMULATION_riscv64= elf64lriscv
 295 LD_EMULATION_sparc64= elf64_sparc_fbsd
 296 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}