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 .if ${COMPILER_VERSION} >= 100000
  42 NO_WMISLEADING_INDENTATION=     -Wno-misleading-indentation
  43 .endif
  44
  45 CLANG_NO_IAS= -no-integrated-as
  46 .if ${COMPILER_VERSION} < 30500
  47 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
  48 CLANG_NO_IAS34= -no-integrated-as
  49 .endif
  50 .endif
  51
  52 .if ${COMPILER_TYPE} == "gcc"
  53 .if ${COMPILER_VERSION} >= 40800
  54 # Catch-all for all the things that are in our tree, but for which we're
  55 # not yet ready for this compiler.
  56 NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
  57 CWARNEXTRA?=    -Wno-error=address                              \
  58                 -Wno-error=aggressive-loop-optimizations        \
  59                 -Wno-error=array-bounds                         \
  60                 -Wno-error=attributes                           \
  61                 -Wno-error=cast-qual                            \
  62                 -Wno-error=enum-compare                         \
  63                 -Wno-error=inline                               \
  64                 -Wno-error=maybe-uninitialized                  \
  65                 -Wno-error=overflow                             \
  66                 -Wno-error=sequence-point                       \
  67                 -Wno-error=unused-but-set-variable
  68 .if ${COMPILER_VERSION} >= 60100
  69 CWARNEXTRA+=    -Wno-error=misleading-indentation               \
  70                 -Wno-error=nonnull-compare                      \
  71                 -Wno-error=shift-overflow                       \
  72                 -Wno-error=tautological-compare
  73 .endif
  74 .if ${COMPILER_VERSION} >= 70200
  75 CWARNEXTRA+=    -Wno-error=memset-elt-size
  76 .endif
  77 .if ${COMPILER_VERSION} >= 80000
  78 CWARNEXTRA+=    -Wno-error=packed-not-aligned
  79 .endif
  80 .else
  81 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  82 CWARNEXTRA?=    -Wno-uninitialized
  83 # GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
  84 # the few files that are already known to generate cast-qual warnings.
  85 NO_WCAST_QUAL= -Wno-cast-qual
  86 .endif
  87 .endif
  88
  89 # This warning is utter nonsense
  90 CWARNFLAGS+=    -Wno-format-zero-length
  91
  92 # External compilers may not support our format extensions.  Allow them
  93 # to be disabled.  WARNING: format checking is disabled in this case.
  94 .if ${MK_FORMAT_EXTENSIONS} == "no"
  95 FORMAT_EXTENSIONS=      -Wno-format
  96 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  97 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  98 .else
  99 FORMAT_EXTENSIONS=      -fformat-extensions
 100 .endif
 101
 102 #
 103 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
 104 # and above adds code to the entry and exit point of every function to align the
 105 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
 106 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
 107 # it is probably an overall loss as it makes the code bigger (less efficient
 108 # use of code cache tag lines) and uses more stack (less efficient use of data
 109 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
 110 # operations inside the kernel itself.  These operations are exclusively
 111 # reserved for user applications.
 112 #
 113 # gcc:
 114 # Setting -mno-mmx implies -mno-3dnow
 115 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
 116 #
 117 # clang:
 118 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 119 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 120 #
 121 .if ${MACHINE_CPUARCH} == "i386"
 122 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 123 CFLAGS.clang+=  -mno-aes -mno-avx
 124 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 125 INLINE_LIMIT?=  8000
 126 .endif
 127
 128 .if ${MACHINE_CPUARCH} == "arm"
 129 INLINE_LIMIT?=  8000
 130 .endif
 131
 132 .if ${MACHINE_CPUARCH} == "aarch64"
 133 # We generally don't want fpu instructions in the kernel.
 134 CFLAGS += -mgeneral-regs-only
 135 # Reserve x18 for pcpu data
 136 CFLAGS += -ffixed-x18
 137 INLINE_LIMIT?=  8000
 138 .endif
 139
 140 #
 141 # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating
 142 # point registers within the kernel. We also specify the "medium" code model,
 143 # which generates code suitable for a 2GiB addressing range located at any
 144 # offset, allowing modules to be located anywhere in the 64-bit address space.
 145 # Note that clang and GCC refer to this code model as "medium" and "medany"
 146 # respectively.
 147 #
 148 .if ${MACHINE_CPUARCH} == "riscv"
 149 CFLAGS+=        -march=rv64imafdc -mabi=lp64
 150 CFLAGS.clang+=  -mcmodel=medium
 151 CFLAGS.gcc+=    -mcmodel=medany
 152 INLINE_LIMIT?=  8000
 153
 154 .if ${LINKER_FEATURES:Mriscv-relaxations} == ""
 155 CFLAGS+=        -mno-relax
 156 .endif
 157 .endif
 158
 159 #
 160 # For sparc64 we want the medany code model so modules may be located
 161 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 162 # point emulation.  This avoids using floating point registers for integer
 163 # operations which it has a tendency to do.
 164 #
 165 .if ${MACHINE_CPUARCH} == "sparc64"
 166 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 167 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 168 INLINE_LIMIT?=  15000
 169 .endif
 170
 171 #
 172 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 173 # operations inside the kernel itself.  These operations are exclusively
 174 # reserved for user applications.
 175 #
 176 # gcc:
 177 # Setting -mno-mmx implies -mno-3dnow
 178 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 179 #
 180 # clang:
 181 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 182 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 183 # (-mfpmath= is not supported)
 184 #
 185 .if ${MACHINE_CPUARCH} == "amd64"
 186 CFLAGS.clang+=  -mno-aes -mno-avx
 187 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 188                 -fno-asynchronous-unwind-tables
 189 INLINE_LIMIT?=  8000
 190 .endif
 191
 192 #
 193 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 194 # floating point registers for integer operations which it has a tendency to do.
 195 # Also explicitly disable Altivec instructions inside the kernel.
 196 #
 197 .if ${MACHINE_CPUARCH} == "powerpc"
 198 CFLAGS+=        -mno-altivec -msoft-float
 199 INLINE_LIMIT?=  15000
 200 .endif
 201
 202 .if ${MACHINE_ARCH} == "powerpcspe"
 203 CFLAGS.gcc+=    -mno-spe
 204 .endif
 205
 206 #
 207 # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
 208 # DDB happy. ELFv2, if available, has some other efficiency benefits.
 209 #
 210 .if ${MACHINE_ARCH} == "powerpc64"
 211 .if ${COMPILER_VERSION} >= 40900
 212 CFLAGS.gcc+=    -mabi=elfv2
 213 .else
 214 CFLAGS.gcc+=    -mcall-aixdesc
 215 .endif
 216 CFLAGS.clang+=  -mabi=elfv2
 217 .endif
 218
 219 #
 220 # For MIPS we also tell gcc to use floating point emulation
 221 #
 222 .if ${MACHINE_CPUARCH} == "mips"
 223 CFLAGS+=        -msoft-float
 224 INLINE_LIMIT?=  8000
 225 .endif
 226
 227 #
 228 # GCC 3.0 and above like to do certain optimizations based on the
 229 # assumption that the program is linked against libc.  Stop this.
 230 #
 231 CFLAGS+=        -ffreestanding
 232
 233 #
 234 # The C standard leaves signed integer overflow behavior undefined.
 235 # gcc and clang opimizers take advantage of this.  The kernel makes
 236 # use of signed integer wraparound mechanics so we need the compiler
 237 # to treat it as a wraparound and not take shortcuts.
 238 #
 239 CFLAGS+=        -fwrapv
 240
 241 #
 242 # GCC SSP support
 243 #
 244 .if ${MK_SSP} != "no" && \
 245     ${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
 246 CFLAGS+=        -fstack-protector
 247 .endif
 248
 249 #
 250 # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
 251 #
 252 .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
 253     ${MK_KERNEL_RETPOLINE} != "no"
 254 CFLAGS+=        -mretpoline
 255 .endif
 256
 257 #
 258 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 259 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 260 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 261 # understand. Do this unconditionally as it is harmless when not needed,
 262 # but critical for these newer versions.
 263 #
 264 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 265 CFLAGS+=        -gdwarf-2
 266 .endif
 267
 268 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 269 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 270
 271 # Tell bmake not to mistake standard targets for things to be searched for
 272 # or expect to ever be up-to-date.
 273 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 274                 beforelinking build build-tools buildfiles buildincludes \
 275                 checkdpadd clean cleandepend cleandir cleanobj configure \
 276                 depend distclean distribute exe \
 277                 html includes install installfiles installincludes \
 278                 obj objlink objs objwarn \
 279                 realinstall regress \
 280                 tags whereobj
 281
 282 .PHONY: ${PHONY_NOTMAIN}
 283 .NOTMAIN: ${PHONY_NOTMAIN}
 284
 285 CSTD=           c99
 286
 287 .if ${CSTD} == "k&r"
 288 CFLAGS+=        -traditional
 289 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 290 CFLAGS+=        -std=iso9899:1990
 291 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 292 CFLAGS+=        -std=iso9899:199409
 293 .elif ${CSTD} == "c99"
 294 CFLAGS+=        -std=iso9899:1999
 295 .else # CSTD
 296 CFLAGS+=        -std=${CSTD}
 297 .endif # CSTD
 298
 299 # Set target-specific linker emulation name.
 300 LD_EMULATION_aarch64=aarch64elf
 301 LD_EMULATION_amd64=elf_x86_64_fbsd
 302 LD_EMULATION_arm=armelf_fbsd
 303 LD_EMULATION_armv6=armelf_fbsd
 304 LD_EMULATION_armv7=armelf_fbsd
 305 LD_EMULATION_i386=elf_i386_fbsd
 306 LD_EMULATION_mips= elf32btsmip_fbsd
 307 LD_EMULATION_mipshf= elf32btsmip_fbsd
 308 LD_EMULATION_mips64= elf64btsmip_fbsd
 309 LD_EMULATION_mips64hf= elf64btsmip_fbsd
 310 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 311 LD_EMULATION_mipselhf= elf32ltsmip_fbsd
 312 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 313 LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
 314 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 315 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 316 LD_EMULATION_powerpc= elf32ppc_fbsd
 317 LD_EMULATION_powerpcspe= elf32ppc_fbsd
 318 LD_EMULATION_powerpc64= elf64ppc_fbsd
 319 LD_EMULATION_riscv64= elf64lriscv
 320 LD_EMULATION_sparc64= elf64_sparc_fbsd
 321 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}