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-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
  37 CLANG_NO_IAS= -no-integrated-as
  38 .if ${COMPILER_VERSION} < 30500
  39 # XXX: clang < 3.5 integrated-as doesn't grok .codeNN directives
  40 CLANG_NO_IAS34= -no-integrated-as
  41 .endif
  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 CWARNEXTRA?=    -Wno-error=address                              \
  49                 -Wno-error=aggressive-loop-optimizations        \
  50                 -Wno-error=array-bounds                         \
  51                 -Wno-error=attributes                           \
  52                 -Wno-error=cast-qual                            \
  53                 -Wno-error=enum-compare                         \
  54                 -Wno-error=inline                               \
  55                 -Wno-error=maybe-uninitialized                  \
  56                 -Wno-error=overflow                             \
  57                 -Wno-error=sequence-point                       \
  58                 -Wno-error=strict-overflow                      \
  59                 -Wno-error=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 .else
  67 # For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
  68 CWARNEXTRA?=    -Wno-uninitialized
  69 .endif
  70 .endif
  71
  72 # External compilers may not support our format extensions.  Allow them
  73 # to be disabled.  WARNING: format checking is disabled in this case.
  74 .if ${MK_FORMAT_EXTENSIONS} == "no"
  75 FORMAT_EXTENSIONS=      -Wno-format
  76 .elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
  77 FORMAT_EXTENSIONS=      -D__printf__=__freebsd_kprintf__
  78 .else
  79 FORMAT_EXTENSIONS=      -fformat-extensions
  80 .endif
  81
  82 #
  83 # On i386, do not align the stack to 16-byte boundaries.  Otherwise GCC 2.95
  84 # and above adds code to the entry and exit point of every function to align the
  85 # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
  86 # per function call.  While the 16-byte alignment may benefit micro benchmarks,
  87 # it is probably an overall loss as it makes the code bigger (less efficient
  88 # use of code cache tag lines) and uses more stack (less efficient use of data
  89 # cache tag lines).  Explicitly prohibit the use of FPU, SSE and other SIMD
  90 # operations inside the kernel itself.  These operations are exclusively
  91 # reserved for user applications.
  92 #
  93 # gcc:
  94 # Setting -mno-mmx implies -mno-3dnow
  95 # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
  96 #
  97 # clang:
  98 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
  99 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 100 #
 101 .if ${MACHINE_CPUARCH} == "i386"
 102 CFLAGS.gcc+=    -mno-align-long-strings -mpreferred-stack-boundary=2
 103 CFLAGS.clang+=  -mno-aes -mno-avx
 104 CFLAGS+=        -mno-mmx -mno-sse -msoft-float
 105 INLINE_LIMIT?=  8000
 106 .endif
 107
 108 .if ${MACHINE_CPUARCH} == "arm"
 109 INLINE_LIMIT?=  8000
 110 .endif
 111
 112 .if ${MACHINE_CPUARCH} == "aarch64"
 113 # We generally don't want fpu instructions in the kernel.
 114 CFLAGS += -mgeneral-regs-only
 115 # Reserve x18 for pcpu data
 116 CFLAGS += -ffixed-x18
 117 .endif
 118
 119 .if ${MACHINE_CPUARCH} == "riscv"
 120 CFLAGS.gcc+=    -mcmodel=medany
 121 INLINE_LIMIT?=  8000
 122 .endif
 123
 124 #
 125 # For sparc64 we want the medany code model so modules may be located
 126 # anywhere in the 64-bit address space.  We also tell GCC to use floating
 127 # point emulation.  This avoids using floating point registers for integer
 128 # operations which it has a tendency to do.
 129 #
 130 .if ${MACHINE_CPUARCH} == "sparc64"
 131 CFLAGS.clang+=  -mcmodel=large -fno-dwarf2-cfi-asm
 132 CFLAGS.gcc+=    -mcmodel=medany -msoft-float
 133 INLINE_LIMIT?=  15000
 134 .endif
 135
 136 #
 137 # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
 138 # operations inside the kernel itself.  These operations are exclusively
 139 # reserved for user applications.
 140 #
 141 # gcc:
 142 # Setting -mno-mmx implies -mno-3dnow
 143 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
 144 #
 145 # clang:
 146 # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
 147 # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
 148 # (-mfpmath= is not supported)
 149 #
 150 .if ${MACHINE_CPUARCH} == "amd64"
 151 CFLAGS.clang+=  -mno-aes -mno-avx
 152 CFLAGS+=        -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
 153                 -fno-asynchronous-unwind-tables
 154 INLINE_LIMIT?=  8000
 155 .endif
 156
 157 #
 158 # For PowerPC we tell gcc to use floating point emulation.  This avoids using
 159 # floating point registers for integer operations which it has a tendency to do.
 160 # Also explicitly disable Altivec instructions inside the kernel.
 161 #
 162 .if ${MACHINE_CPUARCH} == "powerpc"
 163 CFLAGS+=        -mno-altivec
 164 CFLAGS.clang+=  -mllvm -disable-ppc-float-in-variadic=true
 165 CFLAGS.gcc+=    -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 # Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
 208 # and gcc 4.8 is to generate DWARF version 4. However, our tools don't
 209 # cope well with DWARF 4, so force it to genereate DWARF2, which they
 210 # understand. Do this unconditionally as it is harmless when not needed,
 211 # but critical for these newer versions.
 212 #
 213 .if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
 214 CFLAGS+=        -gdwarf-2
 215 .endif
 216
 217 CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
 218 CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
 219
 220 # Tell bmake not to mistake standard targets for things to be searched for
 221 # or expect to ever be up-to-date.
 222 PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
 223                 beforelinking build build-tools buildfiles buildincludes \
 224                 checkdpadd clean cleandepend cleandir cleanobj configure \
 225                 depend distclean distribute exe \
 226                 html includes install installfiles installincludes lint \
 227                 obj objlink objs objwarn \
 228                 realinstall regress \
 229                 tags whereobj
 230
 231 .PHONY: ${PHONY_NOTMAIN}
 232 .NOTMAIN: ${PHONY_NOTMAIN}
 233
 234 CSTD=           c99
 235
 236 .if ${CSTD} == "k&r"
 237 CFLAGS+=        -traditional
 238 .elif ${CSTD} == "c89" || ${CSTD} == "c90"
 239 CFLAGS+=        -std=iso9899:1990
 240 .elif ${CSTD} == "c94" || ${CSTD} == "c95"
 241 CFLAGS+=        -std=iso9899:199409
 242 .elif ${CSTD} == "c99"
 243 CFLAGS+=        -std=iso9899:1999
 244 .else # CSTD
 245 CFLAGS+=        -std=${CSTD}
 246 .endif # CSTD
 247
 248 # Set target-specific linker emulation name. Used by ld -b binary to convert
 249 # binary files into ELF objects.
 250 LD_EMULATION_aarch64=aarch64elf
 251 LD_EMULATION_amd64=elf_x86_64_fbsd
 252 LD_EMULATION_arm=armelf_fbsd
 253 LD_EMULATION_armeb=armelf_fbsd
 254 LD_EMULATION_armv6=armelf_fbsd
 255 LD_EMULATION_i386=elf_i386_fbsd
 256 LD_EMULATION_mips= elf32btsmip_fbsd
 257 LD_EMULATION_mips64= elf64btsmip_fbsd
 258 LD_EMULATION_mipsel= elf32ltsmip_fbsd
 259 LD_EMULATION_mips64el= elf64ltsmip_fbsd
 260 LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
 261 LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd   # I don't think this is a thing that works
 262 LD_EMULATION_powerpc= elf32ppc_fbsd
 263 LD_EMULATION_powerpc64= elf64ppc_fbsd
 264 LD_EMULATION_riscv= elf64riscv
 265 LD_EMULATION_sparc64= elf64_sparc_fbsd
 266 LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}