# $FreeBSD$ # # Warning flags for compiling the kernel and components of the kernel: # CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \ -Wmissing-prototypes -Wpointer-arith -Wcast-qual \ -Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \ -Wmissing-include-dirs -fdiagnostics-show-option \ -Wno-unknown-pragmas \ ${CWARNEXTRA} # # The following flags are next up for working on: # -Wextra # Disable a few warnings for clang, since there are several places in the # kernel where fixing them is more trouble than it is worth, or where there is # a false positive. .if ${COMPILER_TYPE} == "clang" NO_WCONSTANT_CONVERSION= -Wno-error=constant-conversion NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow NO_WSELF_ASSIGN= -Wno-self-assign NO_WUNNEEDED_INTERNAL_DECL= -Wno-error=unneeded-internal-declaration NO_WSOMETIMES_UNINITIALIZED= -Wno-error=sometimes-uninitialized NO_WCAST_QUAL= -Wno-error=cast-qual NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare .if ${COMPILER_VERSION} >= 100000 NO_WMISLEADING_INDENTATION= -Wno-misleading-indentation .endif # Several other warnings which might be useful in some cases, but not severe # enough to error out the whole kernel build. Display them anyway, so there is # some incentive to fix them eventually. CWARNEXTRA?= -Wno-error=tautological-compare -Wno-error=empty-body \ -Wno-error=parentheses-equality -Wno-error=unused-function \ -Wno-error=pointer-sign CWARNEXTRA+= -Wno-error=shift-negative-value CWARNEXTRA+= -Wno-address-of-packed-member .if ${COMPILER_VERSION} >= 130000 CWARNFLAGS+= -Wno-error=unused-but-set-variable .endif .endif # clang .if ${COMPILER_TYPE} == "gcc" # Catch-all for all the things that are in our tree, but for which we're # not yet ready for this compiler. NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable CWARNEXTRA?= -Wno-error=address \ -Wno-error=aggressive-loop-optimizations \ -Wno-error=array-bounds \ -Wno-error=attributes \ -Wno-error=cast-qual \ -Wno-error=enum-compare \ -Wno-error=maybe-uninitialized \ -Wno-error=misleading-indentation \ -Wno-error=nonnull-compare \ -Wno-error=overflow \ -Wno-error=sequence-point \ -Wno-error=shift-overflow \ -Wno-error=tautological-compare \ -Wno-unused-but-set-variable .if ${COMPILER_VERSION} >= 70100 CWARNEXTRA+= -Wno-error=stringop-overflow .endif .if ${COMPILER_VERSION} >= 70200 CWARNEXTRA+= -Wno-error=memset-elt-size .endif .if ${COMPILER_VERSION} >= 80000 CWARNEXTRA+= -Wno-error=packed-not-aligned .endif .if ${COMPILER_VERSION} >= 90100 CWARNEXTRA+= -Wno-address-of-packed-member \ -Wno-error=alloca-larger-than= .endif .endif # gcc # This warning is utter nonsense CWARNFLAGS+= -Wno-format-zero-length # External compilers may not support our format extensions. Allow them # to be disabled. WARNING: format checking is disabled in this case. .if ${MK_FORMAT_EXTENSIONS} == "no" FORMAT_EXTENSIONS= -Wno-format .elif ${COMPILER_TYPE} == "clang" FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__ .else FORMAT_EXTENSIONS= -fformat-extensions .endif # # On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95 # and above adds code to the entry and exit point of every function to align the # stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack # per function call. While the 16-byte alignment may benefit micro benchmarks, # it is probably an overall loss as it makes the code bigger (less efficient # use of code cache tag lines) and uses more stack (less efficient use of data # cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD # operations inside the kernel itself. These operations are exclusively # reserved for user applications. # # gcc: # Setting -mno-mmx implies -mno-3dnow # Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3 # # clang: # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 # .if ${MACHINE_CPUARCH} == "i386" CFLAGS.gcc+= -mpreferred-stack-boundary=2 CFLAGS.clang+= -mno-aes -mno-avx CFLAGS+= -mno-mmx -mno-sse -msoft-float INLINE_LIMIT?= 8000 .endif .if ${MACHINE_CPUARCH} == "arm" INLINE_LIMIT?= 8000 .endif .if ${MACHINE_CPUARCH} == "aarch64" # We generally don't want fpu instructions in the kernel. CFLAGS += -mgeneral-regs-only # Reserve x18 for pcpu data CFLAGS += -ffixed-x18 INLINE_LIMIT?= 8000 .endif # # For RISC-V we specify the soft-float ABI (lp64) to avoid the use of floating # point registers within the kernel. However, for kernels supporting hardware # float (FPE), we have to include that in the march so we can have limited # floating point support in context switching needed for that. This is different # than userland where we use a hard-float ABI (lp64d). # # We also specify the "medium" code model, which generates code suitable for a # 2GiB addressing range located at any offset, allowing modules to be located # anywhere in the 64-bit address space. Note that clang and GCC refer to this # code model as "medium" and "medany" respectively. # .if ${MACHINE_CPUARCH} == "riscv" CFLAGS+= -march=rv64imafdc CFLAGS+= -mabi=lp64 CFLAGS.clang+= -mcmodel=medium CFLAGS.gcc+= -mcmodel=medany INLINE_LIMIT?= 8000 .if ${LINKER_FEATURES:Mriscv-relaxations} == "" CFLAGS+= -mno-relax .endif .endif # # For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD # operations inside the kernel itself. These operations are exclusively # reserved for user applications. # # gcc: # Setting -mno-mmx implies -mno-3dnow # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387 # # clang: # Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa # Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42 # (-mfpmath= is not supported) # .if ${MACHINE_CPUARCH} == "amd64" CFLAGS.clang+= -mno-aes -mno-avx CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \ -fno-asynchronous-unwind-tables INLINE_LIMIT?= 8000 .endif # # For PowerPC we tell gcc to use floating point emulation. This avoids using # floating point registers for integer operations which it has a tendency to do. # Also explicitly disable Altivec instructions inside the kernel. # .if ${MACHINE_CPUARCH} == "powerpc" CFLAGS+= -mno-altivec -msoft-float INLINE_LIMIT?= 15000 .endif .if ${MACHINE_ARCH} == "powerpcspe" CFLAGS.gcc+= -mno-spe .endif # # Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make # DDB happy. ELFv2, if available, has some other efficiency benefits. # .if ${MACHINE_ARCH:Mpowerpc64*} != "" CFLAGS+= -mabi=elfv2 .endif # # For MIPS we also tell gcc to use floating point emulation # .if ${MACHINE_CPUARCH} == "mips" CFLAGS+= -msoft-float INLINE_LIMIT?= 8000 .endif # # GCC 3.0 and above like to do certain optimizations based on the # assumption that the program is linked against libc. Stop this. # CFLAGS+= -ffreestanding # # The C standard leaves signed integer overflow behavior undefined. # gcc and clang opimizers take advantage of this. The kernel makes # use of signed integer wraparound mechanics so we need the compiler # to treat it as a wraparound and not take shortcuts. # CFLAGS+= -fwrapv # # GCC SSP support # .if ${MK_SSP} != "no" CFLAGS+= -fstack-protector .endif # # Retpoline speculative execution vulnerability mitigation (CVE-2017-5715) # .if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \ ${MK_KERNEL_RETPOLINE} != "no" CFLAGS+= -mretpoline .endif # # Initialize stack variables on function entry # .if ${MK_INIT_ALL_ZERO} == "yes" .if ${COMPILER_FEATURES:Minit-all} CFLAGS+= -ftrivial-auto-var-init=zero \ -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang .else .warning InitAll (zeros) requested but not support by compiler .endif .elif ${MK_INIT_ALL_PATTERN} == "yes" .if ${COMPILER_FEATURES:Minit-all} CFLAGS+= -ftrivial-auto-var-init=pattern .else .warning InitAll (pattern) requested but not support by compiler .endif .endif CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}} CFLAGS+= ${CWARNFLAGS.${COMPILER_TYPE}} CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}} # Tell bmake not to mistake standard targets for things to be searched for # or expect to ever be up-to-date. PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \ beforelinking build build-tools buildfiles buildincludes \ checkdpadd clean cleandepend cleandir cleanobj configure \ depend distclean distribute exe \ html includes install installfiles installincludes \ obj objlink objs objwarn \ realinstall regress \ tags whereobj .PHONY: ${PHONY_NOTMAIN} .NOTMAIN: ${PHONY_NOTMAIN} CSTD= c99 .if ${CSTD} == "k&r" CFLAGS+= -traditional .elif ${CSTD} == "c89" || ${CSTD} == "c90" CFLAGS+= -std=iso9899:1990 .elif ${CSTD} == "c94" || ${CSTD} == "c95" CFLAGS+= -std=iso9899:199409 .elif ${CSTD} == "c99" CFLAGS+= -std=iso9899:1999 .else # CSTD CFLAGS+= -std=${CSTD} .endif # CSTD # Please keep this if in sync with bsd.sys.mk .if ${LD} != "ld" && (${CC:[1]:H} != ${LD:[1]:H} || ${LD:[1]:T} != "ld") # Add -fuse-ld=${LD} if $LD is in a different directory or not called "ld". .if ${COMPILER_TYPE} == "clang" # Note: Clang does not like relative paths for ld so we map ld.lld -> lld. .if ${COMPILER_VERSION} >= 120000 CCLDFLAGS+= --ld-path=${LD:[1]:S/^ld.//1W} .else CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W} .endif .else # GCC does not support an absolute path for -fuse-ld so we just print this # warning instead and let the user add the required symlinks. # However, we can avoid this warning if -B is set appropriately (e.g. for # CROSS_TOOLCHAIN=...-gcc). .if !(${LD:[1]:T} == "ld" && ${CC:tw:M-B${LD:[1]:H}/}) .warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported .endif .endif .endif # Set target-specific linker emulation name. LD_EMULATION_aarch64=aarch64elf LD_EMULATION_amd64=elf_x86_64_fbsd LD_EMULATION_arm=armelf_fbsd LD_EMULATION_armv6=armelf_fbsd LD_EMULATION_armv7=armelf_fbsd LD_EMULATION_i386=elf_i386_fbsd LD_EMULATION_mips= elf32btsmip_fbsd LD_EMULATION_mipshf= elf32btsmip_fbsd LD_EMULATION_mips64= elf64btsmip_fbsd LD_EMULATION_mips64hf= elf64btsmip_fbsd LD_EMULATION_mipsel= elf32ltsmip_fbsd LD_EMULATION_mipselhf= elf32ltsmip_fbsd LD_EMULATION_mips64el= elf64ltsmip_fbsd LD_EMULATION_mips64elhf= elf64ltsmip_fbsd LD_EMULATION_mipsn32= elf32btsmipn32_fbsd LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works LD_EMULATION_powerpc= elf32ppc_fbsd LD_EMULATION_powerpcspe= elf32ppc_fbsd LD_EMULATION_powerpc64= elf64ppc_fbsd LD_EMULATION_powerpc64le= elf64lppc_fbsd LD_EMULATION_riscv64= elf64lriscv LD_EMULATION_riscv64sf= elf64lriscv LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}