1 2# 3# Warning flags for compiling the kernel and components of the kernel: 4# 5CWARNFLAGS?= -Wall -Wstrict-prototypes \ 6 -Wmissing-prototypes -Wpointer-arith -Wcast-qual \ 7 -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \ 8 -Wmissing-include-dirs -fdiagnostics-show-option \ 9 -Wno-unknown-pragmas -Wswitch \ 10 ${CWARNEXTRA} 11# 12# The following flags are next up for working on: 13# -Wextra 14 15# Disable a few warnings for clang, since there are several places in the 16# kernel where fixing them is more trouble than it is worth, or where there is 17# a false positive. 18.if ${COMPILER_TYPE} == "clang" 19NO_WCONSTANT_CONVERSION= -Wno-error=constant-conversion 20NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative 21NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow 22NO_WSELF_ASSIGN= -Wno-self-assign 23NO_WUNNEEDED_INTERNAL_DECL= -Wno-error=unneeded-internal-declaration 24NO_WSOMETIMES_UNINITIALIZED= -Wno-error=sometimes-uninitialized 25NO_WCAST_QUAL= -Wno-error=cast-qual 26NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare 27.if ${COMPILER_VERSION} >= 100000 28NO_WMISLEADING_INDENTATION= -Wno-misleading-indentation 29.endif 30.if ${COMPILER_VERSION} >= 130000 31NO_WUNUSED_BUT_SET_VARIABLE= -Wno-unused-but-set-variable 32.endif 33.if ${COMPILER_VERSION} >= 140000 34NO_WBITWISE_INSTEAD_OF_LOGICAL= -Wno-bitwise-instead-of-logical 35.endif 36.if ${COMPILER_VERSION} >= 150000 37NO_WSTRICT_PROTOTYPES= -Wno-strict-prototypes 38NO_WDEPRECATED_NON_PROTOTYPE= -Wno-deprecated-non-prototype 39.endif 40# Several other warnings which might be useful in some cases, but not severe 41# enough to error out the whole kernel build. Display them anyway, so there is 42# some incentive to fix them eventually. 43CWARNEXTRA?= -Wno-error=tautological-compare -Wno-error=empty-body \ 44 -Wno-error=parentheses-equality -Wno-error=unused-function \ 45 -Wno-error=pointer-sign 46CWARNEXTRA+= -Wno-error=shift-negative-value 47CWARNEXTRA+= -Wno-address-of-packed-member 48.endif # clang 49 50.if ${COMPILER_TYPE} == "gcc" 51# Catch-all for all the things that are in our tree, but for which we're 52# not yet ready for this compiler. 53NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable 54CWARNEXTRA?= -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=maybe-uninitialized \ 61 -Wno-error=misleading-indentation \ 62 -Wno-error=nonnull-compare \ 63 -Wno-error=overflow \ 64 -Wno-error=sequence-point \ 65 -Wno-error=shift-overflow \ 66 -Wno-error=tautological-compare \ 67 -Wno-error=unused-function 68.if ${COMPILER_VERSION} >= 70100 69CWARNEXTRA+= -Wno-error=stringop-overflow 70.endif 71.if ${COMPILER_VERSION} >= 70200 72CWARNEXTRA+= -Wno-error=memset-elt-size 73.endif 74.if ${COMPILER_VERSION} >= 80000 75CWARNEXTRA+= -Wno-error=packed-not-aligned 76.endif 77.if ${COMPILER_VERSION} >= 90100 78CWARNEXTRA+= -Wno-address-of-packed-member \ 79 -Wno-alloc-size-larger-than \ 80 -Wno-error=alloca-larger-than= 81.if ${COMPILER_VERSION} >= 120100 82CWARNEXTRA+= -Wno-error=nonnull \ 83 -Wno-dangling-pointer \ 84 -Wno-zero-length-bounds 85NO_WINFINITE_RECURSION= -Wno-infinite-recursion 86NO_WSTRINGOP_OVERREAD= -Wno-stringop-overread 87.endif 88.endif 89 90# GCC produces false positives for functions that switch on an 91# enum (GCC bug 87950) 92CWARNFLAGS+= -Wno-return-type 93.endif # gcc 94 95# This warning is utter nonsense 96CWARNFLAGS+= -Wno-format-zero-length 97 98# External compilers may not support our format extensions. Allow them 99# to be disabled. WARNING: format checking is disabled in this case. 100.if ${MK_FORMAT_EXTENSIONS} == "no" 101FORMAT_EXTENSIONS= -Wno-format 102.elif ${COMPILER_TYPE} == "clang" || \ 103 (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100) 104FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ 105.else 106FORMAT_EXTENSIONS= -fformat-extensions 107.endif 108 109# 110# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 111# and above adds code to the entry and exit point of every function to align the 112# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack 113# per function call. While the 16-byte alignment may benefit micro benchmarks, 114# it is probably an overall loss as it makes the code bigger (less efficient 115# use of code cache tag lines) and uses more stack (less efficient use of data 116# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD 117# operations inside the kernel itself. These operations are exclusively 118# reserved for user applications. 119# 120# gcc: 121# Setting -mno-mmx implies -mno-3dnow 122# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 123# 124# clang: 125# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 126# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 127# 128.if ${MACHINE_CPUARCH} == "i386" 129CFLAGS.gcc+= -mpreferred-stack-boundary=2 130CFLAGS.clang+= -mno-aes -mno-avx 131CFLAGS+= -mno-mmx -mno-sse -msoft-float 132INLINE_LIMIT?= 8000 133.endif 134 135.if ${MACHINE_CPUARCH} == "arm" 136INLINE_LIMIT?= 8000 137.endif 138 139.if ${MACHINE_CPUARCH} == "aarch64" 140# We generally don't want fpu instructions in the kernel. 141CFLAGS += -mgeneral-regs-only 142# Reserve x18 for pcpu data 143CFLAGS += -ffixed-x18 144# Build with BTI+PAC 145CFLAGS += -mbranch-protection=standard 146INLINE_LIMIT?= 8000 147.endif 148 149# 150# For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating 151# point registers within the kernel. However, we include the F and D extensions 152# in -march so we can have limited floating point support in context switching 153# code. This is different than userland where we use a hard-float ABI (lp64d). 154# 155# We also specify the "medium" code model, which generates code suitable for a 156# 2GiB addressing range located at any offset, allowing modules to be located 157# anywhere in the 64-bit address space. Note that clang and GCC refer to this 158# code model as "medium" and "medany" respectively. 159# 160.if ${MACHINE_CPUARCH} == "riscv" 161CFLAGS+= -march=rv64imafdc 162CFLAGS+= -mabi=lp64 163CFLAGS.clang+= -mcmodel=medium 164CFLAGS.gcc+= -mcmodel=medany 165INLINE_LIMIT?= 8000 166 167.if ${LINKER_FEATURES:Mriscv-relaxations} == "" 168CFLAGS+= -mno-relax 169.endif 170.endif 171 172# 173# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD 174# operations inside the kernel itself. These operations are exclusively 175# reserved for user applications. 176# 177# gcc: 178# Setting -mno-mmx implies -mno-3dnow 179# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387 180# 181# clang: 182# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 183# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 184# (-mfpmath= is not supported) 185# 186.if ${MACHINE_CPUARCH} == "amd64" 187CFLAGS.clang+= -mno-aes -mno-avx 188CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ 189 -fno-asynchronous-unwind-tables 190INLINE_LIMIT?= 8000 191.endif 192 193# 194# For PowerPC we tell gcc to use floating point emulation. This avoids using 195# floating point registers for integer operations which it has a tendency to do. 196# Also explicitly disable Altivec instructions inside the kernel. 197# 198.if ${MACHINE_CPUARCH} == "powerpc" 199CFLAGS+= -mno-altivec -msoft-float 200INLINE_LIMIT?= 15000 201.endif 202 203.if ${MACHINE_ARCH} == "powerpcspe" 204CFLAGS.gcc+= -mno-spe 205.endif 206 207# 208# Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make 209# DDB happy. ELFv2, if available, has some other efficiency benefits. 210# 211.if ${MACHINE_ARCH:Mpowerpc64*} != "" && \ 212 ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000 213CFLAGS+= -mabi=elfv2 214.endif 215 216# 217# GCC 3.0 and above like to do certain optimizations based on the 218# assumption that the program is linked against libc. Stop this. 219# 220CFLAGS+= -ffreestanding 221 222# 223# The C standard leaves signed integer overflow behavior undefined. 224# gcc and clang opimizers take advantage of this. The kernel makes 225# use of signed integer wraparound mechanics so we need the compiler 226# to treat it as a wraparound and not take shortcuts. 227# 228CFLAGS+= -fwrapv 229 230# 231# GCC SSP support 232# 233.if ${MK_SSP} != "no" 234CFLAGS+= -fstack-protector 235.endif 236 237# 238# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) 239# 240.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ 241 ${MK_KERNEL_RETPOLINE} != "no" 242CFLAGS+= -mretpoline 243.endif 244 245# 246# Initialize stack variables on function entry 247# 248.if ${OPT_INIT_ALL} != "none" 249.if ${COMPILER_FEATURES:Minit-all} 250CFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL} 251.if ${OPT_INIT_ALL} == "zero" && ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000 252CFLAGS+= -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 253.endif 254.else 255.warning INIT_ALL (${OPT_INIT_ALL}) requested but not supported by compiler 256.endif 257.endif 258 259# 260# Some newer toolchains default to DWARF 5, which isn't supported by some build 261# tools yet. 262# 263.if (${CFLAGS:M-g} != "" || ${CFLAGS:M-g[0-3]} != "") && ${CFLAGS:M-gdwarf*} == "" 264CFLAGS+= -gdwarf-4 265.endif 266 267CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} 268CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} 269CFLAGS+= ${CFLAGS.${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. 273PHONY_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 285CSTD?= gnu99 286 287.if ${CSTD} == "k&r" 288CFLAGS+= -traditional 289.elif ${CSTD} == "c89" || ${CSTD} == "c90" 290CFLAGS+= -std=iso9899:1990 291.elif ${CSTD} == "c94" || ${CSTD} == "c95" 292CFLAGS+= -std=iso9899:199409 293.elif ${CSTD} == "c99" 294CFLAGS+= -std=iso9899:1999 295.else # CSTD 296CFLAGS+= -std=${CSTD} 297.endif # CSTD 298 299# Please keep this if in sync with bsd.sys.mk 300.if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") 301# Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". 302.if ${COMPILER_TYPE} == "clang" 303# Note: Clang does not like relative paths for ld so we map ld.lld -> lld. 304.if ${COMPILER_VERSION} >= 120000 305CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} 306.else 307CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} 308.endif 309.else 310# GCC does not support an absolute path for -fuse-ld so we just print this 311# warning instead and let the user add the required symlinks. 312# However, we can avoid this warning if -B is set appropriately (e.g. for 313# CROSS_TOOLCHAIN=...-gcc). 314.if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) 315.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported 316.endif 317.endif 318.endif 319 320# Set target-specific linker emulation name. 321LD_EMULATION_aarch64=aarch64elf 322LD_EMULATION_amd64=elf_x86_64_fbsd 323LD_EMULATION_arm=armelf_fbsd 324LD_EMULATION_armv6=armelf_fbsd 325LD_EMULATION_armv7=armelf_fbsd 326LD_EMULATION_i386=elf_i386_fbsd 327LD_EMULATION_powerpc= elf32ppc_fbsd 328LD_EMULATION_powerpcspe= elf32ppc_fbsd 329LD_EMULATION_powerpc64= elf64ppc_fbsd 330LD_EMULATION_powerpc64le= elf64lppc_fbsd 331LD_EMULATION_riscv64= elf64lriscv 332LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}} 333