82334850ea
Unmapped mbufs allow sendfile to carry multiple pages of data in a single mbuf, without mapping those pages. It is a requirement for Netflix's in-kernel TLS, and provides a 5-10% CPU savings on heavy web serving workloads when used by sendfile, due to effectively compressing socket buffers by an order of magnitude, and hence reducing cache misses. For this new external mbuf buffer type (EXT_PGS), the ext_buf pointer now points to a struct mbuf_ext_pgs structure instead of a data buffer. This structure contains an array of physical addresses (this reduces cache misses compared to an earlier version that stored an array of vm_page_t pointers). It also stores additional fields needed for in-kernel TLS such as the TLS header and trailer data that are currently unused. To more easily detect these mbufs, the M_NOMAP flag is set in m_flags in addition to M_EXT. Various functions like m_copydata() have been updated to safely access packet contents (using uiomove_fromphys()), to make things like BPF safe. NIC drivers advertise support for unmapped mbufs on transmit via a new IFCAP_NOMAP capability. This capability can be toggled via the new 'nomap' and '-nomap' ifconfig(8) commands. For NIC drivers that only transmit packet contents via DMA and use bus_dma, adding the capability to if_capabilities and if_capenable should be all that is required. If a NIC does not support unmapped mbufs, they are converted to a chain of mapped mbufs (using sf_bufs to provide the mapping) in ip_output or ip6_output. If an unmapped mbuf requires software checksums, it is also converted to a chain of mapped mbufs before computing the checksum. Submitted by: gallatin (earlier version) Reviewed by: gallatin, hselasky, rrs Discussed with: ae, kp (firewalls) Relnotes: yes Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D20616
299 lines
9.6 KiB
Makefile
299 lines
9.6 KiB
Makefile
# $FreeBSD$
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#
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# Warning flags for compiling the kernel and components of the kernel:
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#
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CWARNFLAGS?= -Wall -Wredundant-decls -Wnested-externs -Wstrict-prototypes \
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-Wmissing-prototypes -Wpointer-arith -Wcast-qual \
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-Wundef -Wno-pointer-sign ${FORMAT_EXTENSIONS} \
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-Wmissing-include-dirs -fdiagnostics-show-option \
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-Wno-unknown-pragmas \
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${CWARNEXTRA}
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#
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# The following flags are next up for working on:
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# -Wextra
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# Disable a few warnings for clang, since there are several places in the
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# kernel where fixing them is more trouble than it is worth, or where there is
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# a false positive.
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.if ${COMPILER_TYPE} == "clang"
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NO_WCONSTANT_CONVERSION= -Wno-error-constant-conversion
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NO_WSHIFT_COUNT_NEGATIVE= -Wno-shift-count-negative
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NO_WSHIFT_COUNT_OVERFLOW= -Wno-shift-count-overflow
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NO_WSELF_ASSIGN= -Wno-self-assign
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NO_WUNNEEDED_INTERNAL_DECL= -Wno-error-unneeded-internal-declaration
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NO_WSOMETIMES_UNINITIALIZED= -Wno-error-sometimes-uninitialized
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NO_WCAST_QUAL= -Wno-error-cast-qual
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NO_WTAUTOLOGICAL_POINTER_COMPARE= -Wno-tautological-pointer-compare
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# Several other warnings which might be useful in some cases, but not severe
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# enough to error out the whole kernel build. Display them anyway, so there is
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# some incentive to fix them eventually.
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CWARNEXTRA?= -Wno-error-tautological-compare -Wno-error-empty-body \
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-Wno-error-parentheses-equality -Wno-error-unused-function \
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-Wno-error-pointer-sign
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.if ${COMPILER_VERSION} >= 30700
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CWARNEXTRA+= -Wno-error-shift-negative-value
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.endif
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.if ${COMPILER_VERSION} >= 40000
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CWARNEXTRA+= -Wno-address-of-packed-member
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.endif
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CLANG_NO_IAS= -no-integrated-as
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.endif
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.if ${COMPILER_TYPE} == "gcc"
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.if ${COMPILER_VERSION} >= 40800
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# Catch-all for all the things that are in our tree, but for which we're
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# not yet ready for this compiler.
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NO_WUNUSED_BUT_SET_VARIABLE = -Wno-unused-but-set-variable
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CWARNEXTRA?= -Wno-error=address \
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-Wno-error=aggressive-loop-optimizations \
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-Wno-error=array-bounds \
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-Wno-error=attributes \
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-Wno-error=cast-qual \
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-Wno-error=enum-compare \
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-Wno-error=inline \
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-Wno-error=maybe-uninitialized \
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-Wno-error=overflow \
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-Wno-error=sequence-point \
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-Wno-unused-but-set-variable
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.if ${COMPILER_VERSION} >= 60100
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CWARNEXTRA+= -Wno-error=misleading-indentation \
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-Wno-error=nonnull-compare \
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-Wno-error=shift-overflow \
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-Wno-error=tautological-compare \
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-Wno-format-zero-length
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.endif
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.if ${COMPILER_VERSION} >= 70200
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CWARNEXTRA+= -Wno-error=memset-elt-size
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.endif
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.if ${COMPILER_VERSION} >= 80000
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CWARNEXTRA+= -Wno-error=packed-not-aligned
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.endif
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.else
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# For gcc 4.2, eliminate the too-often-wrong warnings about uninitialized vars.
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CWARNEXTRA?= -Wno-uninitialized
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# GCC 4.2 doesn't have -Wno-error=cast-qual, so just disable the warning for
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# the few files that are already known to generate cast-qual warnings.
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NO_WCAST_QUAL= -Wno-cast-qual
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NO_WNONNULL= -Wno-nonnull
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.endif
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.endif
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# External compilers may not support our format extensions. Allow them
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# to be disabled. WARNING: format checking is disabled in this case.
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.if ${MK_FORMAT_EXTENSIONS} == "no"
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FORMAT_EXTENSIONS= -Wno-format
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.elif ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
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FORMAT_EXTENSIONS= -D__printf__=__freebsd_kprintf__
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.else
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FORMAT_EXTENSIONS= -fformat-extensions
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.endif
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#
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# On i386, do not align the stack to 16-byte boundaries. Otherwise GCC 2.95
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# and above adds code to the entry and exit point of every function to align the
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# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of stack
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# per function call. While the 16-byte alignment may benefit micro benchmarks,
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# it is probably an overall loss as it makes the code bigger (less efficient
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# use of code cache tag lines) and uses more stack (less efficient use of data
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# cache tag lines). Explicitly prohibit the use of FPU, SSE and other SIMD
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# operations inside the kernel itself. These operations are exclusively
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# reserved for user applications.
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#
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# gcc:
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# Setting -mno-mmx implies -mno-3dnow
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# Setting -mno-sse implies -mno-sse2, -mno-sse3 and -mno-ssse3
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#
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# clang:
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# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
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#
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.if ${MACHINE_CPUARCH} == "i386"
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CFLAGS.gcc+= -mno-align-long-strings -mpreferred-stack-boundary=2
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CFLAGS.clang+= -mno-aes -mno-avx
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CFLAGS+= -mno-mmx -mno-sse -msoft-float
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INLINE_LIMIT?= 8000
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.endif
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.if ${MACHINE_CPUARCH} == "arm"
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INLINE_LIMIT?= 8000
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.endif
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.if ${MACHINE_CPUARCH} == "aarch64"
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# We generally don't want fpu instructions in the kernel.
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CFLAGS += -mgeneral-regs-only
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# Reserve x18 for pcpu data
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CFLAGS += -ffixed-x18
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INLINE_LIMIT?= 8000
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.endif
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.if ${MACHINE_CPUARCH} == "riscv"
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CFLAGS.gcc+= -mcmodel=medany -march=rv64imafdc -mabi=lp64
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INLINE_LIMIT?= 8000
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.endif
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#
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# For sparc64 we want the medany code model so modules may be located
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# anywhere in the 64-bit address space. We also tell GCC to use floating
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# point emulation. This avoids using floating point registers for integer
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# operations which it has a tendency to do.
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#
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.if ${MACHINE_CPUARCH} == "sparc64"
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CFLAGS.clang+= -mcmodel=large -fno-dwarf2-cfi-asm
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CFLAGS.gcc+= -mcmodel=medany -msoft-float
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INLINE_LIMIT?= 15000
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.endif
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#
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# For AMD64, we explicitly prohibit the use of FPU, SSE and other SIMD
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# operations inside the kernel itself. These operations are exclusively
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# reserved for user applications.
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#
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# gcc:
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# Setting -mno-mmx implies -mno-3dnow
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387
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#
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# clang:
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# Setting -mno-mmx implies -mno-3dnow and -mno-3dnowa
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# Setting -mno-sse implies -mno-sse2, -mno-sse3, -mno-ssse3, -mno-sse41 and -mno-sse42
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# (-mfpmath= is not supported)
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#
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.if ${MACHINE_CPUARCH} == "amd64"
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CFLAGS.clang+= -mno-aes -mno-avx
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CFLAGS+= -mcmodel=kernel -mno-red-zone -mno-mmx -mno-sse -msoft-float \
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-fno-asynchronous-unwind-tables
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INLINE_LIMIT?= 8000
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.endif
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#
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# For PowerPC we tell gcc to use floating point emulation. This avoids using
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# floating point registers for integer operations which it has a tendency to do.
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# Also explicitly disable Altivec instructions inside the kernel.
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#
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.if ${MACHINE_CPUARCH} == "powerpc"
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CFLAGS+= -mno-altivec -msoft-float
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INLINE_LIMIT?= 15000
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.endif
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.if ${MACHINE_ARCH} == "powerpcspe"
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CFLAGS.gcc+= -mno-spe
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.endif
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#
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# Use dot symbols (or, better, the V2 ELF ABI) on powerpc64 to make
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# DDB happy. ELFv2, if available, has some other efficiency benefits.
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#
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.if ${MACHINE_ARCH} == "powerpc64"
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.if ${COMPILER_VERSION} >= 40900
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CFLAGS.gcc+= -mabi=elfv2
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.else
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CFLAGS.gcc+= -mcall-aixdesc
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.endif
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CFLAGS.clang+= -mabi=elfv2
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.endif
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#
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# For MIPS we also tell gcc to use floating point emulation
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#
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.if ${MACHINE_CPUARCH} == "mips"
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CFLAGS+= -msoft-float
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INLINE_LIMIT?= 8000
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.endif
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#
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# GCC 3.0 and above like to do certain optimizations based on the
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# assumption that the program is linked against libc. Stop this.
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#
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CFLAGS+= -ffreestanding
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#
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# The C standard leaves signed integer overflow behavior undefined.
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# gcc and clang opimizers take advantage of this. The kernel makes
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# use of signed integer wraparound mechanics so we need the compiler
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# to treat it as a wraparound and not take shortcuts.
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#
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CFLAGS+= -fwrapv
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#
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# GCC SSP support
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#
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.if ${MK_SSP} != "no" && \
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${MACHINE_CPUARCH} != "arm" && ${MACHINE_CPUARCH} != "mips"
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CFLAGS+= -fstack-protector
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.endif
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#
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# Retpoline speculative execution vulnerability mitigation (CVE-2017-5715)
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#
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.if defined(COMPILER_FEATURES) && ${COMPILER_FEATURES:Mretpoline} != "" && \
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${MK_KERNEL_RETPOLINE} != "no"
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CFLAGS+= -mretpoline
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.endif
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#
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# Add -gdwarf-2 when compiling -g. The default starting in clang v3.4
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# and gcc 4.8 is to generate DWARF version 4. However, our tools don't
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# cope well with DWARF 4, so force it to genereate DWARF2, which they
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# understand. Do this unconditionally as it is harmless when not needed,
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# but critical for these newer versions.
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#
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.if ${CFLAGS:M-g} != "" && ${CFLAGS:M-gdwarf*} == ""
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CFLAGS+= -gdwarf-2
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.endif
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CFLAGS+= ${CWARNFLAGS:M*} ${CWARNFLAGS.${.IMPSRC:T}}
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CFLAGS+= ${CFLAGS.${COMPILER_TYPE}} ${CFLAGS.${.IMPSRC:T}}
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# Tell bmake not to mistake standard targets for things to be searched for
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# or expect to ever be up-to-date.
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PHONY_NOTMAIN = afterdepend afterinstall all beforedepend beforeinstall \
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beforelinking build build-tools buildfiles buildincludes \
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checkdpadd clean cleandepend cleandir cleanobj configure \
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depend distclean distribute exe \
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html includes install installfiles installincludes \
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obj objlink objs objwarn \
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realinstall regress \
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tags whereobj
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.PHONY: ${PHONY_NOTMAIN}
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.NOTMAIN: ${PHONY_NOTMAIN}
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CSTD= c99
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.if ${CSTD} == "k&r"
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CFLAGS+= -traditional
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.elif ${CSTD} == "c89" || ${CSTD} == "c90"
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CFLAGS+= -std=iso9899:1990
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.elif ${CSTD} == "c94" || ${CSTD} == "c95"
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CFLAGS+= -std=iso9899:199409
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.elif ${CSTD} == "c99"
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CFLAGS+= -std=iso9899:1999
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.else # CSTD
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CFLAGS+= -std=${CSTD}
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.endif # CSTD
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# Set target-specific linker emulation name.
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LD_EMULATION_aarch64=aarch64elf
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LD_EMULATION_amd64=elf_x86_64_fbsd
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LD_EMULATION_arm=armelf_fbsd
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LD_EMULATION_armv6=armelf_fbsd
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LD_EMULATION_armv7=armelf_fbsd
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LD_EMULATION_i386=elf_i386_fbsd
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LD_EMULATION_mips= elf32btsmip_fbsd
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LD_EMULATION_mipshf= elf32btsmip_fbsd
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LD_EMULATION_mips64= elf64btsmip_fbsd
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LD_EMULATION_mips64hf= elf64btsmip_fbsd
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LD_EMULATION_mipsel= elf32ltsmip_fbsd
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LD_EMULATION_mipselhf= elf32ltsmip_fbsd
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LD_EMULATION_mips64el= elf64ltsmip_fbsd
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LD_EMULATION_mips64elhf= elf64ltsmip_fbsd
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LD_EMULATION_mipsn32= elf32btsmipn32_fbsd
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LD_EMULATION_mipsn32el= elf32btsmipn32_fbsd # I don't think this is a thing that works
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LD_EMULATION_powerpc= elf32ppc_fbsd
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LD_EMULATION_powerpcspe= elf32ppc_fbsd
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LD_EMULATION_powerpc64= elf64ppc_fbsd
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LD_EMULATION_riscv64= elf64lriscv
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LD_EMULATION_sparc64= elf64_sparc_fbsd
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LD_EMULATION=${LD_EMULATION_${MACHINE_ARCH}}
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