freebsd-dev/sys/conf/kern.mk
Ed Maste 1e54857bd9 Stop defaulting to DWRAF2 in kernel compilation
After the removal of obsolete GDB 6.1.1 from the base system in
1c0ea326aa we no longer need to downgrade to DWARF2 debug info.

We will need to ensure that our tools (e.g. ctfconvert) handle DWARF5
prior to it becoming the default in the Clang and GCC versions we use.

Reported by:	jhb
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
2020-12-31 15:56:18 -05:00

321 lines
11 KiB
Makefile

# $FreeBSD$
#
# 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
# 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} >= 100000
NO_WMISLEADING_INDENTATION= -Wno-misleading-indentation
.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=inline \
-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
.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" && \
${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
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".
# Note: Clang 12+ will prefer --ld-path= over -fuse-ld=.
.if ${COMPILER_TYPE} == "clang"
# Note: unlike bsd.sys.mk we can't use LDFLAGS here since that is used for the
# flags required when linking the kernel. We don't need those flags when
# building the vdsos. However, we do need -fuse-ld, so use ${CCLDFLAGS} instead.
# Note: Clang does not like relative paths in -fuse-ld so we map ld.lld -> lld.
CCLDFLAGS+= -fuse-ld=${LD:[1]:S/^ld.//1W}
.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.
.warning LD (${LD}) is not the default linker for ${CC} but -fuse-ld= is not supported
.endif
.endif
# Set target-specific linker emulation name.
LD_EMULATION_aarch64=aarch64elf
LD_EMULATION_amd64=elf_x86_64_fbsd
LD_EMULATION_arm=armelf_fbsd
LD_EMULATION_armv6=armelf_fbsd
LD_EMULATION_armv7=armelf_fbsd
LD_EMULATION_i386=elf_i386_fbsd
LD_EMULATION_mips= elf32btsmip_fbsd
LD_EMULATION_mipshf= elf32btsmip_fbsd
LD_EMULATION_mips64= elf64btsmip_fbsd
LD_EMULATION_mips64hf= elf64btsmip_fbsd
LD_EMULATION_mipsel= elf32ltsmip_fbsd
LD_EMULATION_mipselhf= elf32ltsmip_fbsd
LD_EMULATION_mips64el= elf64ltsmip_fbsd
LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
LD_EMULATION_powerpc= elf32ppc_fbsd
LD_EMULATION_powerpcspe= elf32ppc_fbsd
LD_EMULATION_powerpc64= elf64ppc_fbsd
LD_EMULATION_powerpc64le= elf64lppc_fbsd
LD_EMULATION_riscv64= elf64lriscv
LD_EMULATION_riscv64sf= elf64lriscv
LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}