1# $FreeBSD$ 2 3# 4# Warning flags for compiling the kernel and components of the kernel: 5# 6CWARNFLAGS?= -Wall -Wnested-externs -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# Several other warnings which might be useful in some cases, but not severe 38# enough to error out the whole kernel build. Display them anyway, so there is 39# some incentive to fix them eventually. 40CWARNEXTRA?= -Wno-error=tautological-compare -Wno-error=empty-body \ 41 -Wno-error=parentheses-equality -Wno-error=unused-function \ 42 -Wno-error=pointer-sign 43CWARNEXTRA+= -Wno-error=shift-negative-value 44CWARNEXTRA+= -Wno-address-of-packed-member 45.if ${COMPILER_VERSION} >= 130000 46.if ${MK_SET_BUT_NOTUSED_KERNEL_WARNINGS} == "no" 47CWARNEXTRA+= ${NO_WUNUSED_BUT_SET_VARIABLE} 48.else 49CWARNEXTRA+= -Wno-error=unused-but-set-variable 50.endif 51.endif 52.endif # clang 53 54.if ${COMPILER_TYPE} == "gcc" 55# Catch-all for all the things that are in our tree, but for which we're 56# not yet ready for this compiler. 57NO_WUNUSED_BUT_SET_VARIABLE=-Wno-unused-but-set-variable 58CWARNEXTRA?= -Wno-error=address \ 59 -Wno-error=aggressive-loop-optimizations \ 60 -Wno-error=array-bounds \ 61 -Wno-error=attributes \ 62 -Wno-error=cast-qual \ 63 -Wno-error=enum-compare \ 64 -Wno-error=maybe-uninitialized \ 65 -Wno-error=misleading-indentation \ 66 -Wno-error=nonnull-compare \ 67 -Wno-error=overflow \ 68 -Wno-error=sequence-point \ 69 -Wno-error=shift-overflow \ 70 -Wno-error=tautological-compare \ 71 -Wno-unused-but-set-variable 72.if ${COMPILER_VERSION} >= 70100 73CWARNEXTRA+= -Wno-error=stringop-overflow 74.endif 75.if ${COMPILER_VERSION} >= 70200 76CWARNEXTRA+= -Wno-error=memset-elt-size 77.endif 78.if ${COMPILER_VERSION} >= 80000 79CWARNEXTRA+= -Wno-error=packed-not-aligned 80.endif 81.if ${COMPILER_VERSION} >= 90100 82CWARNEXTRA+= -Wno-address-of-packed-member \ 83 -Wno-error=alloca-larger-than= 84.endif 85 86# GCC produces false positives for functions that switch on an 87# enum (GCC bug 87950) 88CWARNFLAGS+= -Wno-return-type 89.endif # gcc 90 91# This warning is utter nonsense 92CWARNFLAGS+= -Wno-format-zero-length 93 94# External compilers may not support our format extensions. Allow them 95# to be disabled. WARNING: format checking is disabled in this case. 96.if ${MK_FORMAT_EXTENSIONS} == "no" 97FORMAT_EXTENSIONS= -Wno-format 98.elif ${COMPILER_TYPE} == "clang" 99FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ 100.else 101FORMAT_EXTENSIONS= -fformat-extensions 102.endif 103 104# 105# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 106# and above adds code to the entry and exit point of every function to align the 107# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack 108# per function call. While the 16-byte alignment may benefit micro benchmarks, 109# it is probably an overall loss as it makes the code bigger (less efficient 110# use of code cache tag lines) and uses more stack (less efficient use of data 111# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD 112# operations inside the kernel itself. These operations are exclusively 113# reserved for user applications. 114# 115# gcc: 116# Setting -mno-mmx implies -mno-3dnow 117# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 118# 119# clang: 120# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 121# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 122# 123.if ${MACHINE_CPUARCH} == "i386" 124CFLAGS.gcc+= -mpreferred-stack-boundary=2 125CFLAGS.clang+= -mno-aes -mno-avx 126CFLAGS+= -mno-mmx -mno-sse -msoft-float 127INLINE_LIMIT?= 8000 128.endif 129 130.if ${MACHINE_CPUARCH} == "arm" 131INLINE_LIMIT?= 8000 132.endif 133 134.if ${MACHINE_CPUARCH} == "aarch64" 135# We generally don't want fpu instructions in the kernel. 136CFLAGS += -mgeneral-regs-only 137# Reserve x18 for pcpu data 138CFLAGS += -ffixed-x18 139INLINE_LIMIT?= 8000 140.endif 141 142# 143# For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating 144# point registers within the kernel. However, for kernels supporting hardware 145# float (FPE), we have to include that in the march so we can have limited 146# floating point support in context switching needed for that. This is different 147# than userland where we use a hard-float ABI (lp64d). 148# 149# We also specify the "medium" code model, which generates code suitable for a 150# 2GiB addressing range located at any offset, allowing modules to be located 151# anywhere in the 64-bit address space. Note that clang and GCC refer to this 152# code model as "medium" and "medany" respectively. 153# 154.if ${MACHINE_CPUARCH} == "riscv" 155CFLAGS+= -march=rv64imafdc 156CFLAGS+= -mabi=lp64 157CFLAGS.clang+= -mcmodel=medium 158CFLAGS.gcc+= -mcmodel=medany 159INLINE_LIMIT?= 8000 160 161.if ${LINKER_FEATURES:Mriscv-relaxations} == "" 162CFLAGS+= -mno-relax 163.endif 164.endif 165 166# 167# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD 168# operations inside the kernel itself. These operations are exclusively 169# reserved for user applications. 170# 171# gcc: 172# Setting -mno-mmx implies -mno-3dnow 173# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387 174# 175# clang: 176# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 177# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 178# (-mfpmath= is not supported) 179# 180.if ${MACHINE_CPUARCH} == "amd64" 181CFLAGS.clang+= -mno-aes -mno-avx 182CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ 183 -fno-asynchronous-unwind-tables 184INLINE_LIMIT?= 8000 185.endif 186 187# 188# For PowerPC we tell gcc to use floating point emulation. This avoids using 189# floating point registers for integer operations which it has a tendency to do. 190# Also explicitly disable Altivec instructions inside the kernel. 191# 192.if ${MACHINE_CPUARCH} == "powerpc" 193CFLAGS+= -mno-altivec -msoft-float 194INLINE_LIMIT?= 15000 195.endif 196 197.if ${MACHINE_ARCH} == "powerpcspe" 198CFLAGS.gcc+= -mno-spe 199.endif 200 201# 202# Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make 203# DDB happy. ELFv2, if available, has some other efficiency benefits. 204# 205.if ${MACHINE_ARCH:Mpowerpc64*} != "" 206CFLAGS+= -mabi=elfv2 207.endif 208 209# 210# GCC 3.0 and above like to do certain optimizations based on the 211# assumption that the program is linked against libc. Stop this. 212# 213CFLAGS+= -ffreestanding 214 215# 216# The C standard leaves signed integer overflow behavior undefined. 217# gcc and clang opimizers take advantage of this. The kernel makes 218# use of signed integer wraparound mechanics so we need the compiler 219# to treat it as a wraparound and not take shortcuts. 220# 221CFLAGS+= -fwrapv 222 223# 224# GCC SSP support 225# 226.if ${MK_SSP} != "no" 227CFLAGS+= -fstack-protector 228.endif 229 230# 231# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) 232# 233.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ 234 ${MK_KERNEL_RETPOLINE} != "no" 235CFLAGS+= -mretpoline 236.endif 237 238# 239# Initialize stack variables on function entry 240# 241.if ${MK_INIT_ALL_ZERO} == "yes" 242.if ${COMPILER_FEATURES:Minit-all} 243CFLAGS+= -ftrivial-auto-var-init=zero \ 244 -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 245.else 246.warning InitAll (zeros) requested but not support by compiler 247.endif 248.elif ${MK_INIT_ALL_PATTERN} == "yes" 249.if ${COMPILER_FEATURES:Minit-all} 250CFLAGS+= -ftrivial-auto-var-init=pattern 251.else 252.warning InitAll (pattern) requested but not support by compiler 253.endif 254.endif 255 256CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} 257CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} 258CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}} 259 260# Tell bmake not to mistake standard targets for things to be searched for 261# or expect to ever be up-to-date. 262PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \ 263 beforelinking build build-tools buildfiles buildincludes \ 264 checkdpadd clean cleandepend cleandir cleanobj configure \ 265 depend distclean distribute exe \ 266 html includes install installfiles installincludes \ 267 obj objlink objs objwarn \ 268 realinstall regress \ 269 tags whereobj 270 271.PHONY: ${PHONY_NOTMAIN} 272.NOTMAIN: ${PHONY_NOTMAIN} 273 274CSTD= c99 275 276.if ${CSTD} == "k&r" 277CFLAGS+= -traditional 278.elif ${CSTD} == "c89" || ${CSTD} == "c90" 279CFLAGS+= -std=iso9899:1990 280.elif ${CSTD} == "c94" || ${CSTD} == "c95" 281CFLAGS+= -std=iso9899:199409 282.elif ${CSTD} == "c99" 283CFLAGS+= -std=iso9899:1999 284.else # CSTD 285CFLAGS+= -std=${CSTD} 286.endif # CSTD 287 288# Please keep this if in sync with bsd.sys.mk 289.if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") 290# Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". 291.if ${COMPILER_TYPE} == "clang" 292# Note: Clang does not like relative paths for ld so we map ld.lld -> lld. 293.if ${COMPILER_VERSION} >= 120000 294CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} 295.else 296CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} 297.endif 298.else 299# GCC does not support an absolute path for -fuse-ld so we just print this 300# warning instead and let the user add the required symlinks. 301# However, we can avoid this warning if -B is set appropriately (e.g. for 302# CROSS_TOOLCHAIN=...-gcc). 303.if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) 304.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported 305.endif 306.endif 307.endif 308 309# Set target-specific linker emulation name. 310LD_EMULATION_aarch64=aarch64elf 311LD_EMULATION_amd64=elf_x86_64_fbsd 312LD_EMULATION_arm=armelf_fbsd 313LD_EMULATION_armv6=armelf_fbsd 314LD_EMULATION_armv7=armelf_fbsd 315LD_EMULATION_i386=elf_i386_fbsd 316LD_EMULATION_powerpc= elf32ppc_fbsd 317LD_EMULATION_powerpcspe= elf32ppc_fbsd 318LD_EMULATION_powerpc64= elf64ppc_fbsd 319LD_EMULATION_powerpc64le= elf64lppc_fbsd 320LD_EMULATION_riscv64= elf64lriscv 321LD_EMULATION_riscv64sf= elf64lriscv 322LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}} 323