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 \ 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-error=alloca-larger-than= 80.if ${COMPILER_VERSION} >= 120100 81CWARNEXTRA+= -Wno-error=nonnull \ 82 -Wno-dangling-pointer \ 83 -Wno-zero-length-bounds 84NO_WINFINITE_RECURSION= -Wno-infinite-recursion 85NO_WSTRINGOP_OVERREAD= -Wno-stringop-overread 86.endif 87.endif 88 89# GCC produces false positives for functions that switch on an 90# enum (GCC bug 87950) 91CWARNFLAGS+= -Wno-return-type 92.endif # gcc 93 94# This warning is utter nonsense 95CWARNFLAGS+= -Wno-format-zero-length 96 97# External compilers may not support our format extensions. Allow them 98# to be disabled. WARNING: format checking is disabled in this case. 99.if ${MK_FORMAT_EXTENSIONS} == "no" 100FORMAT_EXTENSIONS= -Wno-format 101.elif ${COMPILER_TYPE} == "clang" || \ 102 (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 120100) 103FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ 104.else 105FORMAT_EXTENSIONS= -fformat-extensions 106.endif 107 108# 109# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 110# and above adds code to the entry and exit point of every function to align the 111# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack 112# per function call. While the 16-byte alignment may benefit micro benchmarks, 113# it is probably an overall loss as it makes the code bigger (less efficient 114# use of code cache tag lines) and uses more stack (less efficient use of data 115# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD 116# operations inside the kernel itself. These operations are exclusively 117# reserved for user applications. 118# 119# gcc: 120# Setting -mno-mmx implies -mno-3dnow 121# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 122# 123# clang: 124# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 125# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 126# 127.if ${MACHINE_CPUARCH} == "i386" 128CFLAGS.gcc+= -mpreferred-stack-boundary=2 129CFLAGS.clang+= -mno-aes -mno-avx 130CFLAGS+= -mno-mmx -mno-sse -msoft-float 131INLINE_LIMIT?= 8000 132.endif 133 134.if ${MACHINE_CPUARCH} == "arm" 135INLINE_LIMIT?= 8000 136.endif 137 138.if ${MACHINE_CPUARCH} == "aarch64" 139# We generally don't want fpu instructions in the kernel. 140CFLAGS += -mgeneral-regs-only 141# Reserve x18 for pcpu data 142CFLAGS += -ffixed-x18 143# Build with BTI+PAC 144CFLAGS += -mbranch-protection=standard 145INLINE_LIMIT?= 8000 146.endif 147 148# 149# For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating 150# point registers within the kernel. However, we include the F and D extensions 151# in -march so we can have limited floating point support in context switching 152# code. This is different than userland where we use a hard-float ABI (lp64d). 153# 154# We also specify the "medium" code model, which generates code suitable for a 155# 2GiB addressing range located at any offset, allowing modules to be located 156# anywhere in the 64-bit address space. Note that clang and GCC refer to this 157# code model as "medium" and "medany" respectively. 158# 159.if ${MACHINE_CPUARCH} == "riscv" 160CFLAGS+= -march=rv64imafdc 161CFLAGS+= -mabi=lp64 162CFLAGS.clang+= -mcmodel=medium 163CFLAGS.gcc+= -mcmodel=medany 164INLINE_LIMIT?= 8000 165 166.if ${LINKER_FEATURES:Mriscv-relaxations} == "" 167CFLAGS+= -mno-relax 168.endif 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" 186CFLAGS.clang+= -mno-aes -mno-avx 187CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ 188 -fno-asynchronous-unwind-tables 189INLINE_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" 198CFLAGS+= -mno-altivec -msoft-float 199INLINE_LIMIT?= 15000 200.endif 201 202.if ${MACHINE_ARCH} == "powerpcspe" 203CFLAGS.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:Mpowerpc64*} != "" && \ 211 ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000 212CFLAGS+= -mabi=elfv2 213.endif 214 215# 216# GCC 3.0 and above like to do certain optimizations based on the 217# assumption that the program is linked against libc. Stop this. 218# 219CFLAGS+= -ffreestanding 220 221# 222# The C standard leaves signed integer overflow behavior undefined. 223# gcc and clang opimizers take advantage of this. The kernel makes 224# use of signed integer wraparound mechanics so we need the compiler 225# to treat it as a wraparound and not take shortcuts. 226# 227CFLAGS+= -fwrapv 228 229# 230# GCC SSP support 231# 232.if ${MK_SSP} != "no" 233CFLAGS+= -fstack-protector 234.endif 235 236# 237# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) 238# 239.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ 240 ${MK_KERNEL_RETPOLINE} != "no" 241CFLAGS+= -mretpoline 242.endif 243 244# 245# Initialize stack variables on function entry 246# 247.if ${OPT_INIT_ALL} != "none" 248.if ${COMPILER_FEATURES:Minit-all} 249CFLAGS+= -ftrivial-auto-var-init=${OPT_INIT_ALL} 250.if ${OPT_INIT_ALL} == "zero" && ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} < 160000 251CFLAGS+= -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 252.endif 253.else 254.warning INIT_ALL (${OPT_INIT_ALL}) requested but not supported by compiler 255.endif 256.endif 257 258CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} 259CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} 260CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}} 261 262# Tell bmake not to mistake standard targets for things to be searched for 263# or expect to ever be up-to-date. 264PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \ 265 beforelinking build build-tools buildfiles buildincludes \ 266 checkdpadd clean cleandepend cleandir cleanobj configure \ 267 depend distclean distribute exe \ 268 html includes install installfiles installincludes \ 269 obj objlink objs objwarn \ 270 realinstall regress \ 271 tags whereobj 272 273.PHONY: ${PHONY_NOTMAIN} 274.NOTMAIN: ${PHONY_NOTMAIN} 275 276CSTD?= gnu99 277 278.if ${CSTD} == "k&r" 279CFLAGS+= -traditional 280.elif ${CSTD} == "c89" || ${CSTD} == "c90" 281CFLAGS+= -std=iso9899:1990 282.elif ${CSTD} == "c94" || ${CSTD} == "c95" 283CFLAGS+= -std=iso9899:199409 284.elif ${CSTD} == "c99" 285CFLAGS+= -std=iso9899:1999 286.else # CSTD 287CFLAGS+= -std=${CSTD} 288.endif # CSTD 289 290# Please keep this if in sync with bsd.sys.mk 291.if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") 292# Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". 293.if ${COMPILER_TYPE} == "clang" 294# Note: Clang does not like relative paths for ld so we map ld.lld -> lld. 295.if ${COMPILER_VERSION} >= 120000 296CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} 297.else 298CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} 299.endif 300.else 301# GCC does not support an absolute path for -fuse-ld so we just print this 302# warning instead and let the user add the required symlinks. 303# However, we can avoid this warning if -B is set appropriately (e.g. for 304# CROSS_TOOLCHAIN=...-gcc). 305.if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) 306.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported 307.endif 308.endif 309.endif 310 311# Set target-specific linker emulation name. 312LD_EMULATION_aarch64=aarch64elf 313LD_EMULATION_amd64=elf_x86_64_fbsd 314LD_EMULATION_arm=armelf_fbsd 315LD_EMULATION_armv6=armelf_fbsd 316LD_EMULATION_armv7=armelf_fbsd 317LD_EMULATION_i386=elf_i386_fbsd 318LD_EMULATION_powerpc= elf32ppc_fbsd 319LD_EMULATION_powerpcspe= elf32ppc_fbsd 320LD_EMULATION_powerpc64= elf64ppc_fbsd 321LD_EMULATION_powerpc64le= elf64lppc_fbsd 322LD_EMULATION_riscv64= elf64lriscv 323LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}} 324