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