1# $FreeBSD$ 2 3# 4# Warning flags for compiling the kernel and components of the kernel: 5# 6CWARNFLAGS?= -Wall -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" 20NO_WCONSTANT_CONVERSION= -Wno-error=constant-conversion 21NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative 22NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow 23NO_WSELF_ASSIGN= -Wno-self-assign 24NO_WUNNEEDED_INTERNAL_DECL= -Wno-error=unneeded-internal-declaration 25NO_WSOMETIMES_UNINITIALIZED= -Wno-error=sometimes-uninitialized 26NO_WCAST_QUAL= -Wno-error=cast-qual 27NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare 28.if ${COMPILER_VERSION} >= 100000 29NO_WMISLEADING_INDENTATION= -Wno-misleading-indentation 30.endif 31.if ${COMPILER_VERSION} >= 130000 32NO_WUNUSED_BUT_SET_VARIABLE= -Wno-unused-but-set-variable 33.endif 34.if ${COMPILER_VERSION} >= 140000 35NO_WBITWISE_INSTEAD_OF_LOGICAL= -Wno-bitwise-instead-of-logical 36.endif 37.if ${COMPILER_VERSION} >= 150000 38NO_WSTRICT_PROTOTYPES= -Wno-strict-prototypes 39NO_WDEPRECATED_NON_PROTOTYPE= -Wno-deprecated-non-prototype 40.endif 41# Several other warnings which might be useful in some cases, but not severe 42# enough to error out the whole kernel build. Display them anyway, so there is 43# some incentive to fix them eventually. 44CWARNEXTRA?= -Wno-error=tautological-compare -Wno-error=empty-body \ 45 -Wno-error=parentheses-equality -Wno-error=unused-function \ 46 -Wno-error=pointer-sign 47CWARNEXTRA+= -Wno-error=shift-negative-value 48CWARNEXTRA+= -Wno-address-of-packed-member 49.if ${COMPILER_VERSION} >= 150000 50# Clang 15 has much more aggressive diagnostics about 51# mismatched prototypes and unused-but-set variables. Make these 52# non-fatal for the time being. 53CWARNEXTRA+= -Wno-error=strict-prototypes 54CWARNEXTRA+= -Wno-error=unused-but-set-variable 55.endif 56.endif # clang 57 58.if ${COMPILER_TYPE} == "gcc" 59# Catch-all for all the things that are in our tree, but for which we're 60# not yet ready for this compiler. 61NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable 62CWARNEXTRA?= -Wno-error=address \ 63 -Wno-error=aggressive-loop-optimizations \ 64 -Wno-error=array-bounds \ 65 -Wno-error=attributes \ 66 -Wno-error=cast-qual \ 67 -Wno-error=enum-compare \ 68 -Wno-error=maybe-uninitialized \ 69 -Wno-error=misleading-indentation \ 70 -Wno-error=nonnull-compare \ 71 -Wno-error=overflow \ 72 -Wno-error=sequence-point \ 73 -Wno-error=shift-overflow \ 74 -Wno-error=tautological-compare \ 75 -Wno-error=unused-function 76.if ${COMPILER_VERSION} >= 70100 77CWARNEXTRA+= -Wno-error=stringop-overflow 78.endif 79.if ${COMPILER_VERSION} >= 70200 80CWARNEXTRA+= -Wno-error=memset-elt-size 81.endif 82.if ${COMPILER_VERSION} >= 80000 83CWARNEXTRA+= -Wno-error=packed-not-aligned 84.endif 85.if ${COMPILER_VERSION} >= 90100 86CWARNEXTRA+= -Wno-address-of-packed-member \ 87 -Wno-error=alloca-larger-than= 88.if ${COMPILER_VERSION} >= 120100 89CWARNEXTRA+= -Wno-error=nonnull \ 90 -Wno-dangling-pointer \ 91 -Wno-zero-length-bounds 92NO_WINFINITE_RECURSION= -Wno-infinite-recursion 93NO_WSTRINGOP_OVERREAD= -Wno-stringop-overread 94.endif 95.endif 96 97# GCC produces false positives for functions that switch on an 98# enum (GCC bug 87950) 99CWARNFLAGS+= -Wno-return-type 100.endif # gcc 101 102# This warning is utter nonsense 103CWARNFLAGS+= -Wno-format-zero-length 104 105# External compilers may not support our format extensions. Allow them 106# to be disabled. WARNING: format checking is disabled in this case. 107.if ${MK_FORMAT_EXTENSIONS} == "no" 108FORMAT_EXTENSIONS= -Wno-format 109.elif ${COMPILER_TYPE} == "clang" || \ 110 (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100) 111FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ 112.else 113FORMAT_EXTENSIONS= -fformat-extensions 114.endif 115 116# 117# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 118# and above adds code to the entry and exit point of every function to align the 119# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack 120# per function call. While the 16-byte alignment may benefit micro benchmarks, 121# it is probably an overall loss as it makes the code bigger (less efficient 122# use of code cache tag lines) and uses more stack (less efficient use of data 123# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD 124# operations inside the kernel itself. These operations are exclusively 125# reserved for user applications. 126# 127# gcc: 128# Setting -mno-mmx implies -mno-3dnow 129# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 130# 131# clang: 132# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 133# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 134# 135.if ${MACHINE_CPUARCH} == "i386" 136CFLAGS.gcc+= -mpreferred-stack-boundary=2 137CFLAGS.clang+= -mno-aes -mno-avx 138CFLAGS+= -mno-mmx -mno-sse -msoft-float 139INLINE_LIMIT?= 8000 140.endif 141 142.if ${MACHINE_CPUARCH} == "arm" 143INLINE_LIMIT?= 8000 144.endif 145 146.if ${MACHINE_CPUARCH} == "aarch64" 147# We generally don't want fpu instructions in the kernel. 148CFLAGS += -mgeneral-regs-only 149# Reserve x18 for pcpu data 150CFLAGS += -ffixed-x18 151INLINE_LIMIT?= 8000 152.endif 153 154# 155# For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating 156# point registers within the kernel. However, we include the F and D extensions 157# in -march so we can have limited floating point support in context switching 158# code. This is different than userland where we use a hard-float ABI (lp64d). 159# 160# We also specify the "medium" code model, which generates code suitable for a 161# 2GiB addressing range located at any offset, allowing modules to be located 162# anywhere in the 64-bit address space. Note that clang and GCC refer to this 163# code model as "medium" and "medany" respectively. 164# 165.if ${MACHINE_CPUARCH} == "riscv" 166CFLAGS+= -march=rv64imafdc 167CFLAGS+= -mabi=lp64 168CFLAGS.clang+= -mcmodel=medium 169CFLAGS.gcc+= -mcmodel=medany 170INLINE_LIMIT?= 8000 171 172.if ${LINKER_FEATURES:Mriscv-relaxations} == "" 173CFLAGS+= -mno-relax 174.endif 175.endif 176 177# 178# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD 179# operations inside the kernel itself. These operations are exclusively 180# reserved for user applications. 181# 182# gcc: 183# Setting -mno-mmx implies -mno-3dnow 184# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387 185# 186# clang: 187# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 188# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 189# (-mfpmath= is not supported) 190# 191.if ${MACHINE_CPUARCH} == "amd64" 192CFLAGS.clang+= -mno-aes -mno-avx 193CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ 194 -fno-asynchronous-unwind-tables 195INLINE_LIMIT?= 8000 196.endif 197 198# 199# For PowerPC we tell gcc to use floating point emulation. This avoids using 200# floating point registers for integer operations which it has a tendency to do. 201# Also explicitly disable Altivec instructions inside the kernel. 202# 203.if ${MACHINE_CPUARCH} == "powerpc" 204CFLAGS+= -mno-altivec -msoft-float 205INLINE_LIMIT?= 15000 206.endif 207 208.if ${MACHINE_ARCH} == "powerpcspe" 209CFLAGS.gcc+= -mno-spe 210.endif 211 212# 213# Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make 214# DDB happy. ELFv2, if available, has some other efficiency benefits. 215# 216.if ${MACHINE_ARCH:Mpowerpc64*} != "" && \ 217 ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000 218CFLAGS+= -mabi=elfv2 219.endif 220 221# 222# GCC 3.0 and above like to do certain optimizations based on the 223# assumption that the program is linked against libc. Stop this. 224# 225CFLAGS+= -ffreestanding 226 227# 228# The C standard leaves signed integer overflow behavior undefined. 229# gcc and clang opimizers take advantage of this. The kernel makes 230# use of signed integer wraparound mechanics so we need the compiler 231# to treat it as a wraparound and not take shortcuts. 232# 233CFLAGS+= -fwrapv 234 235# 236# GCC SSP support 237# 238.if ${MK_SSP} != "no" 239CFLAGS+= -fstack-protector 240.endif 241 242# 243# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) 244# 245.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ 246 ${MK_KERNEL_RETPOLINE} != "no" 247CFLAGS+= -mretpoline 248.endif 249 250# 251# Initialize stack variables on function entry 252# 253.if ${MK_INIT_ALL_ZERO} == "yes" 254.if ${COMPILER_FEATURES:Minit-all} 255CFLAGS+= -ftrivial-auto-var-init=zero \ 256 -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 257.else 258.warning InitAll (zeros) requested but not support by compiler 259.endif 260.elif ${MK_INIT_ALL_PATTERN} == "yes" 261.if ${COMPILER_FEATURES:Minit-all} 262CFLAGS+= -ftrivial-auto-var-init=pattern 263.else 264.warning InitAll (pattern) requested but not support by compiler 265.endif 266.endif 267 268CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} 269CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} 270CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}} 271 272# Tell bmake not to mistake standard targets for things to be searched for 273# or expect to ever be up-to-date. 274PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \ 275 beforelinking build build-tools buildfiles buildincludes \ 276 checkdpadd clean cleandepend cleandir cleanobj configure \ 277 depend distclean distribute exe \ 278 html includes install installfiles installincludes \ 279 obj objlink objs objwarn \ 280 realinstall regress \ 281 tags whereobj 282 283.PHONY: ${PHONY_NOTMAIN} 284.NOTMAIN: ${PHONY_NOTMAIN} 285 286CSTD= c99 287 288.if ${CSTD} == "k&r" 289CFLAGS+= -traditional 290.elif ${CSTD} == "c89" || ${CSTD} == "c90" 291CFLAGS+= -std=iso9899:1990 292.elif ${CSTD} == "c94" || ${CSTD} == "c95" 293CFLAGS+= -std=iso9899:199409 294.elif ${CSTD} == "c99" 295CFLAGS+= -std=iso9899:1999 296.else # CSTD 297CFLAGS+= -std=${CSTD} 298.endif # CSTD 299 300# Please keep this if in sync with bsd.sys.mk 301.if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") 302# Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". 303.if ${COMPILER_TYPE} == "clang" 304# Note: Clang does not like relative paths for ld so we map ld.lld -> lld. 305.if ${COMPILER_VERSION} >= 120000 306CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} 307.else 308CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} 309.endif 310.else 311# GCC does not support an absolute path for -fuse-ld so we just print this 312# warning instead and let the user add the required symlinks. 313# However, we can avoid this warning if -B is set appropriately (e.g. for 314# CROSS_TOOLCHAIN=...-gcc). 315.if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) 316.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported 317.endif 318.endif 319.endif 320 321# Set target-specific linker emulation name. 322LD_EMULATION_aarch64=aarch64elf 323LD_EMULATION_amd64=elf_x86_64_fbsd 324LD_EMULATION_arm=armelf_fbsd 325LD_EMULATION_armv6=armelf_fbsd 326LD_EMULATION_armv7=armelf_fbsd 327LD_EMULATION_i386=elf_i386_fbsd 328LD_EMULATION_powerpc= elf32ppc_fbsd 329LD_EMULATION_powerpcspe= elf32ppc_fbsd 330LD_EMULATION_powerpc64= elf64ppc_fbsd 331LD_EMULATION_powerpc64le= elf64lppc_fbsd 332LD_EMULATION_riscv64= elf64lriscv 333LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}} 334