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 NO_WARRAY_BOUNDS=               -Wno-error-array-bounds
  29 # Several other warnings which might be useful in some cases, but not severe
  30 # enough to error out the whole kernel build.  Display them anyway, so there is
  31 # some incentive to fix them eventually.
  32 CWARNEXTRA?=    -Wno-error-tautological-compare -Wno-error-empty-body \
  33                 -Wno-error-parentheses-equality -Wno-error-unused-function \
  34                 -Wno-error-pointer-sign
  35 .if ${COMPILER_VERSION} >= 30700
  36 CWARNEXTRA+=    -Wno-error-shift-negative-value
  37 .endif
  38 .if ${COMPILER_VERSION} >= 40000
  39 CWARNEXTRA+=    -Wno-address-of-packed-member
  40 .endif
  41
  42 CLANG_NO_IAS= -no-integrated-as
  43 .if ${COMPILER_VERSION} < 30500
  44 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
  45 CLANG_NO_IAS34= -no-integrated-as
  46 .endif
  47 .endif
  48
  49 .if ${COMPILER_TYPE} == "gcc"
  50 .if ${COMPILER_VERSION} >= 40800
  51 # Catch-all for all the things that are in our tree, but for which we're
  52 # not yet ready for this compiler.
  53 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  54 CWARNEXTRA?=    -Wno-error=address                              \
  55                 -Wno-error=aggressive-loop-optimizations        \
  56                 -Wno-error=array-bounds                         \
  57                 -Wno-error=attributes                           \
  58                 -Wno-error=cast-qual                            \
  59                 -Wno-error=enum-compare                         \
  60                 -Wno-error=inline                               \
  61                 -Wno-error=maybe-uninitialized                  \
  62                 -Wno-error=overflow                             \
  63                 -Wno-error=sequence-point                       \
  64                 -Wno-error=unused-but-set-variable
  65 .if ${COMPILER_VERSION} >= 60100
  66 CWARNEXTRA+=    -Wno-error=misleading-indentation               \
  67                 -Wno-error=nonnull-compare                      \
  68                 -Wno-error=shift-overflow                       \
  69                 -Wno-error=tautological-compare
  70 .endif
  71 .if ${COMPILER_VERSION} >= 70200
  72 CWARNEXTRA+=    -Wno-error=memset-elt-size
  73 .endif
  74 .if ${COMPILER_VERSION} >= 80000
  75 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  76 .endif
  77 .else
  78 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  79 CWARNEXTRA?=    -Wno-uninitialized
  80 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
  81 # the few files that are already known to generate cast-qual warnings.
  82 NO_WCAST_QUAL= -Wno-cast-qual
  83 .endif
  84 .endif
  85
  86 # External compilers may not support our format extensions.  Allow them
  87 # to be disabled.  WARNING: format checking is disabled in this case.
  88 .if ${MK_FORMAT_EXTENSIONS} == "no"
  89 FORMAT_EXTENSIONS=      -Wno-format
  90 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  91 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  92 .else
  93 FORMAT_EXTENSIONS=      -fformat-extensions
  94 .endif
  95
  96 #
  97 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  98 # and above adds code to the entry and exit point of every function to align the
  99 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 100 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 101 # it is probably an overall loss as it makes the code bigger (less efficient
 102 # use of code cache tag lines) and uses more stack (less efficient use of data
 103 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 104 # operations inside the kernel itself.  These operations are exclusively
 105 # reserved for user applications.
 106 #
 107 # gcc:
 108 # Setting -mno-mmx implies -mno-3dnow
 109 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 110 #
 111 # clang:
 112 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 113 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 114 #
 115 .if ${MACHINE_CPUARCH} == "i386"
 116 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 117 CFLAGS.clang+=  -mno-aes -mno-avx
 118 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 119 INLINE_LIMIT?=  8000
 120 .endif
 121
 122 .if ${MACHINE_CPUARCH} == "arm"
 123 INLINE_LIMIT?=  8000
 124 .endif
 125
 126 .if ${MACHINE_CPUARCH} == "aarch64"
 127 # We generally don't want fpu instructions in the kernel.
 128 CFLAGS += -mgeneral-regs-only
 129 # Reserve x18 for pcpu data
 130 CFLAGS += -ffixed-x18
 131 INLINE_LIMIT?=  8000
 132 .endif
 133
 134 #
 135 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 136 # point registers within the kernel. We also specify the "medium" code model,
 137 # which generates code suitable for a 2GiB addressing range located at any
 138 # offset, allowing modules to be located anywhere in the 64-bit address space.
 139 # Note that clang and GCC refer to this code model as "medium" and "medany"
 140 # respectively.
 141 #
 142 .if ${MACHINE_CPUARCH} == "riscv"
 143 CFLAGS+=        -march=rv64imafdc -mabi=lp64
 144 CFLAGS.clang+=  -mcmodel=medium
 145 CFLAGS.gcc+=    -mcmodel=medany
 146 INLINE_LIMIT?=  8000
 147 .endif
 148
 149 #
 150 # For sparc64 we want the medany code model so modules may be located
 151 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 152 # point emulation.  This avoids using floating point registers for integer
 153 # operations which it has a tendency to do.
 154 #
 155 .if ${MACHINE_CPUARCH} == "sparc64"
 156 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 157 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 158 INLINE_LIMIT?=  15000
 159 .endif
 160
 161 #
 162 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 163 # operations inside the kernel itself.  These operations are exclusively
 164 # reserved for user applications.
 165 #
 166 # gcc:
 167 # Setting -mno-mmx implies -mno-3dnow
 168 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 169 #
 170 # clang:
 171 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 172 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 173 # (-mfpmath= is not supported)
 174 #
 175 .if ${MACHINE_CPUARCH} == "amd64"
 176 CFLAGS.clang+=  -mno-aes -mno-avx
 177 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 178                 -fno-asynchronous-unwind-tables
 179 INLINE_LIMIT?=  8000
 180 .endif
 181
 182 #
 183 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 184 # floating point registers for integer operations which it has a tendency to do.
 185 # Also explicitly disable Altivec instructions inside the kernel.
 186 #
 187 .if ${MACHINE_CPUARCH} == "powerpc"
 188 CFLAGS+=        -mno-altivec -msoft-float
 189 INLINE_LIMIT?=  15000
 190 .endif
 191
 192 .if ${MACHINE_ARCH} == "powerpcspe"
 193 CFLAGS.gcc+=    -mno-spe
 194 .endif
 195
 196 #
 197 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 198 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 199 #
 200 .if ${MACHINE_ARCH} == "powerpc64"
 201 .if ${COMPILER_VERSION} >= 40900
 202 CFLAGS.gcc+=    -mabi=elfv2
 203 .else
 204 CFLAGS.gcc+=    -mcall-aixdesc
 205 .endif
 206 CFLAGS.clang+=  -mabi=elfv2
 207 .endif
 208
 209 #
 210 # For MIPS we also tell gcc to use floating point emulation
 211 #
 212 .if ${MACHINE_CPUARCH} == "mips"
 213 CFLAGS+=        -msoft-float
 214 INLINE_LIMIT?=  8000
 215 .endif
 216
 217 #
 218 # GCC 3.0 and above like to do certain optimizations based on the
 219 # assumption that the program is linked against libc.  Stop this.
 220 #
 221 CFLAGS+=        -ffreestanding
 222
 223 #
 224 # The C standard leaves signed integer overflow behavior undefined.
 225 # gcc and clang opimizers take advantage of this.  The kernel makes
 226 # use of signed integer wraparound mechanics so we need the compiler
 227 # to treat it as a wraparound and not take shortcuts.
 228 #
 229 CFLAGS+=        -fwrapv
 230
 231 #
 232 # GCC SSP support
 233 #
 234 .if ${MK_SSP} != "no" && \
 235     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 236 CFLAGS+=        -fstack-protector
 237 .endif
 238
 239 #
 240 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 241 #
 242 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 243     ${MK_KERNEL_RETPOLINE} != "no"
 244 CFLAGS+=        -mretpoline
 245 .endif
 246
 247 #
 248 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 249 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 250 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 251 # understand. Do this unconditionally as it is harmless when not needed,
 252 # but critical for these newer versions.
 253 #
 254 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 255 CFLAGS+=        -gdwarf-2
 256 .endif
 257
 258 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 259 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 260
 261 # Tell bmake not to mistake standard targets for things to be searched for
 262 # or expect to ever be up-to-date.
 263 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 264                 beforelinking build build-tools buildfiles buildincludes \
 265                 checkdpadd clean cleandepend cleandir cleanobj configure \
 266                 depend distclean distribute exe \
 267                 html includes install installfiles installincludes \
 268                 obj objlink objs objwarn \
 269                 realinstall regress \
 270                 tags whereobj
 271
 272 .PHONY: ${PHONY_NOTMAIN}
 273 .NOTMAIN: ${PHONY_NOTMAIN}
 274
 275 CSTD=           c99
 276
 277 .if ${CSTD} == "k&r"
 278 CFLAGS+=        -traditional
 279 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 280 CFLAGS+=        -std=iso9899:1990
 281 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 282 CFLAGS+=        -std=iso9899:199409
 283 .elif ${CSTD} == "c99"
 284 CFLAGS+=        -std=iso9899:1999
 285 .else # CSTD
 286 CFLAGS+=        -std=${CSTD}
 287 .endif # CSTD
 288
 289 # Set target-specific linker emulation name.
 290 LD_EMULATION_aarch64=aarch64elf
 291 LD_EMULATION_amd64=elf_x86_64_fbsd
 292 LD_EMULATION_arm=armelf_fbsd
 293 LD_EMULATION_armv6=armelf_fbsd
 294 LD_EMULATION_armv7=armelf_fbsd
 295 LD_EMULATION_i386=elf_i386_fbsd
 296 LD_EMULATION_mips= elf32btsmip_fbsd
 297 LD_EMULATION_mipshf= elf32btsmip_fbsd
 298 LD_EMULATION_mips64= elf64btsmip_fbsd
 299 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 300 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 301 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 302 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 303 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 304 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 305 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 306 LD_EMULATION_powerpc= elf32ppc_fbsd
 307 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 308 LD_EMULATION_powerpc64= elf64ppc_fbsd
 309 LD_EMULATION_riscv64= elf64lriscv
 310 LD_EMULATION_sparc64= elf64_sparc_fbsd
 311 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}