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