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