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.if ${COMPILER_VERSION} >= 150000 38NO_WSTRICT_PROTOTYPES= -Wno-strict-prototypes 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-unused-but-set-variable 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.endif 81 82# GCC produces false positives for functions that switch on an 83# enum (GCC bug 87950) 84CWARNFLAGS+= -Wno-return-type 85.endif # gcc 86 87# This warning is utter nonsense 88CWARNFLAGS+= -Wno-format-zero-length 89 90# External compilers may not support our format extensions. Allow them 91# to be disabled. WARNING: format checking is disabled in this case. 92.if ${MK_FORMAT_EXTENSIONS} == "no" 93FORMAT_EXTENSIONS= -Wno-format 94.elif ${COMPILER_TYPE} == "clang" 95FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ 96.else 97FORMAT_EXTENSIONS= -fformat-extensions 98.endif 99 100# 101# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 102# and above adds code to the entry and exit point of every function to align the 103# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack 104# per function call. While the 16-byte alignment may benefit micro benchmarks, 105# it is probably an overall loss as it makes the code bigger (less efficient 106# use of code cache tag lines) and uses more stack (less efficient use of data 107# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD 108# operations inside the kernel itself. These operations are exclusively 109# reserved for user applications. 110# 111# gcc: 112# Setting -mno-mmx implies -mno-3dnow 113# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 114# 115# clang: 116# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 117# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 118# 119.if ${MACHINE_CPUARCH} == "i386" 120CFLAGS.gcc+= -mpreferred-stack-boundary=2 121CFLAGS.clang+= -mno-aes -mno-avx 122CFLAGS+= -mno-mmx -mno-sse -msoft-float 123INLINE_LIMIT?= 8000 124.endif 125 126.if ${MACHINE_CPUARCH} == "arm" 127INLINE_LIMIT?= 8000 128.endif 129 130.if ${MACHINE_CPUARCH} == "aarch64" 131# We generally don't want fpu instructions in the kernel. 132CFLAGS += -mgeneral-regs-only 133# Reserve x18 for pcpu data 134CFLAGS += -ffixed-x18 135INLINE_LIMIT?= 8000 136.endif 137 138# 139# For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating 140# point registers within the kernel. However, for kernels supporting hardware 141# float (FPE), we have to include that in the march so we can have limited 142# floating point support in context switching needed for that. This is different 143# than userland where we use a hard-float ABI (lp64d). 144# 145# We also specify the "medium" code model, which generates code suitable for a 146# 2GiB addressing range located at any offset, allowing modules to be located 147# anywhere in the 64-bit address space. Note that clang and GCC refer to this 148# code model as "medium" and "medany" respectively. 149# 150.if ${MACHINE_CPUARCH} == "riscv" 151CFLAGS+= -march=rv64imafdc 152CFLAGS+= -mabi=lp64 153CFLAGS.clang+= -mcmodel=medium 154CFLAGS.gcc+= -mcmodel=medany 155INLINE_LIMIT?= 8000 156 157.if ${LINKER_FEATURES:Mriscv-relaxations} == "" 158CFLAGS+= -mno-relax 159.endif 160.endif 161 162# 163# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD 164# operations inside the kernel itself. These operations are exclusively 165# reserved for user applications. 166# 167# gcc: 168# Setting -mno-mmx implies -mno-3dnow 169# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387 170# 171# clang: 172# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa 173# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 174# (-mfpmath= is not supported) 175# 176.if ${MACHINE_CPUARCH} == "amd64" 177CFLAGS.clang+= -mno-aes -mno-avx 178CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ 179 -fno-asynchronous-unwind-tables 180INLINE_LIMIT?= 8000 181.endif 182 183# 184# For PowerPC we tell gcc to use floating point emulation. This avoids using 185# floating point registers for integer operations which it has a tendency to do. 186# Also explicitly disable Altivec instructions inside the kernel. 187# 188.if ${MACHINE_CPUARCH} == "powerpc" 189CFLAGS+= -mno-altivec -msoft-float 190INLINE_LIMIT?= 15000 191.endif 192 193.if ${MACHINE_ARCH} == "powerpcspe" 194CFLAGS.gcc+= -mno-spe 195.endif 196 197# 198# Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make 199# DDB happy. ELFv2, if available, has some other efficiency benefits. 200# 201.if ${MACHINE_ARCH:Mpowerpc64*} != "" 202CFLAGS+= -mabi=elfv2 203.endif 204 205# 206# GCC 3.0 and above like to do certain optimizations based on the 207# assumption that the program is linked against libc. Stop this. 208# 209CFLAGS+= -ffreestanding 210 211# 212# The C standard leaves signed integer overflow behavior undefined. 213# gcc and clang opimizers take advantage of this. The kernel makes 214# use of signed integer wraparound mechanics so we need the compiler 215# to treat it as a wraparound and not take shortcuts. 216# 217CFLAGS+= -fwrapv 218 219# 220# GCC SSP support 221# 222.if ${MK_SSP} != "no" 223CFLAGS+= -fstack-protector 224.endif 225 226# 227# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) 228# 229.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ 230 ${MK_KERNEL_RETPOLINE} != "no" 231CFLAGS+= -mretpoline 232.endif 233 234# 235# Initialize stack variables on function entry 236# 237.if ${MK_INIT_ALL_ZERO} == "yes" 238.if ${COMPILER_FEATURES:Minit-all} 239CFLAGS+= -ftrivial-auto-var-init=zero \ 240 -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang 241.else 242.warning InitAll (zeros) requested but not support by compiler 243.endif 244.elif ${MK_INIT_ALL_PATTERN} == "yes" 245.if ${COMPILER_FEATURES:Minit-all} 246CFLAGS+= -ftrivial-auto-var-init=pattern 247.else 248.warning InitAll (pattern) requested but not support by compiler 249.endif 250.endif 251 252CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} 253CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} 254CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}} 255 256# Tell bmake not to mistake standard targets for things to be searched for 257# or expect to ever be up-to-date. 258PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \ 259 beforelinking build build-tools buildfiles buildincludes \ 260 checkdpadd clean cleandepend cleandir cleanobj configure \ 261 depend distclean distribute exe \ 262 html includes install installfiles installincludes \ 263 obj objlink objs objwarn \ 264 realinstall regress \ 265 tags whereobj 266 267.PHONY: ${PHONY_NOTMAIN} 268.NOTMAIN: ${PHONY_NOTMAIN} 269 270CSTD= c99 271 272.if ${CSTD} == "k&r" 273CFLAGS+= -traditional 274.elif ${CSTD} == "c89" || ${CSTD} == "c90" 275CFLAGS+= -std=iso9899:1990 276.elif ${CSTD} == "c94" || ${CSTD} == "c95" 277CFLAGS+= -std=iso9899:199409 278.elif ${CSTD} == "c99" 279CFLAGS+= -std=iso9899:1999 280.else # CSTD 281CFLAGS+= -std=${CSTD} 282.endif # CSTD 283 284# Please keep this if in sync with bsd.sys.mk 285.if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") 286# Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". 287.if ${COMPILER_TYPE} == "clang" 288# Note: Clang does not like relative paths for ld so we map ld.lld -> lld. 289.if ${COMPILER_VERSION} >= 120000 290CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} 291.else 292CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} 293.endif 294.else 295# GCC does not support an absolute path for -fuse-ld so we just print this 296# warning instead and let the user add the required symlinks. 297# However, we can avoid this warning if -B is set appropriately (e.g. for 298# CROSS_TOOLCHAIN=...-gcc). 299.if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) 300.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported 301.endif 302.endif 303.endif 304 305# Set target-specific linker emulation name. 306LD_EMULATION_aarch64=aarch64elf 307LD_EMULATION_amd64=elf_x86_64_fbsd 308LD_EMULATION_arm=armelf_fbsd 309LD_EMULATION_armv6=armelf_fbsd 310LD_EMULATION_armv7=armelf_fbsd 311LD_EMULATION_i386=elf_i386_fbsd 312LD_EMULATION_powerpc= elf32ppc_fbsd 313LD_EMULATION_powerpcspe= elf32ppc_fbsd 314LD_EMULATION_powerpc64= elf64ppc_fbsd 315LD_EMULATION_powerpc64le= elf64lppc_fbsd 316LD_EMULATION_riscv64= elf64lriscv 317LD_EMULATION_riscv64sf= elf64lriscv 318LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}} 319