Index: head/Makefile
===================================================================
--- head/Makefile
+++ head/Makefile
@@ -180,7 +180,7 @@
 _TARGET_ARCH=	${TARGET:S/pc98/i386/:S/arm64/aarch64/}
 .elif !defined(TARGET) && defined(TARGET_ARCH) && \
     ${TARGET_ARCH} != ${MACHINE_ARCH}
-_TARGET=		${TARGET_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb|hf)?/arm/:C/aarch64/arm64/:C/powerpc64/powerpc/}
+_TARGET=		${TARGET_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb|hf)?/arm/:C/aarch64/arm64/:C/powerpc64/powerpc/:C/riscv64/riscv/}
 .endif
 .if defined(TARGET) && !defined(_TARGET)
 _TARGET=${TARGET}
Index: head/Makefile.inc1
===================================================================
--- head/Makefile.inc1
+++ head/Makefile.inc1
@@ -172,7 +172,11 @@
 .export VERSION
 .endif
 
-KNOWN_ARCHES?=	aarch64/arm64 amd64 arm armeb/arm armv6/arm armv6hf/arm i386 i386/pc98 mips mipsel/mips mips64el/mips mips64/mips mipsn32el/mips mipsn32/mips powerpc powerpc64/powerpc sparc64
+KNOWN_ARCHES?=	aarch64/arm64 amd64 arm armeb/arm armv6/arm armv6hf/arm   \
+		i386 i386/pc98 mips mipsel/mips mips64el/mips mips64/mips \
+		mipsn32el/mips mipsn32/mips powerpc powerpc64/powerpc     \
+		riscv64/riscv sparc64
+
 .if ${TARGET} == ${TARGET_ARCH}
 _t=		${TARGET}
 .else
Index: head/share/mk/bsd.cpu.mk
===================================================================
--- head/share/mk/bsd.cpu.mk
+++ head/share/mk/bsd.cpu.mk
@@ -18,6 +18,8 @@
 MACHINE_CPU = mips
 . elif ${MACHINE_CPUARCH} == "powerpc"
 MACHINE_CPU = aim
+. elif ${MACHINE_CPUARCH} == "riscv"
+MACHINE_CPU = riscv
 . elif ${MACHINE_CPUARCH} == "sparc64"
 MACHINE_CPU = ultrasparc
 . endif
@@ -148,6 +150,8 @@
 #	sb1, xlp, xlr
 _CPUCFLAGS = -march=${CPUTYPE:S/^mips//}
 . endif
+. elif ${MACHINE_CPUARCH} == "riscv"
+_CPUCFLAGS = -msoft-float # -march="RV64I" # RISCVTODO
 . elif ${MACHINE_ARCH} == "sparc64"
 .  if ${CPUTYPE} == "v9"
 _CPUCFLAGS = -mcpu=v9
@@ -277,6 +281,9 @@
 .  if ${CPUTYPE} == "e500"
 MACHINE_CPU = booke softfp
 .  endif
+########## riscv
+. elif ${MACHINE_CPUARCH} == "riscv"
+MACHINE_CPU = riscv
 ########## sparc64
 . elif ${MACHINE_ARCH} == "sparc64"
 .  if ${CPUTYPE} == "v9"
@@ -313,6 +320,10 @@
 .endif
 .endif
 
+.if ${MACHINE_CPUARCH} == "riscv"
+CFLAGS += -msoft-float
+.endif
+
 # NB: COPTFLAGS is handled in /usr/src/sys/conf/kern.pre.mk
 
 .if !defined(NO_CPU_CFLAGS)
Index: head/share/mk/bsd.endian.mk
===================================================================
--- head/share/mk/bsd.endian.mk
+++ head/share/mk/bsd.endian.mk
@@ -4,6 +4,7 @@
     ${MACHINE_ARCH} == "amd64" || \
     ${MACHINE_ARCH} == "i386" || \
     (${MACHINE} == "arm" && ${MACHINE_ARCH:Marm*eb*} == "") || \
+    ${MACHINE_CPUARCH} == "riscv" || \
     ${MACHINE_ARCH:Mmips*el} != ""
 TARGET_ENDIANNESS= 1234
 .elif ${MACHINE_ARCH} == "powerpc" || \
Index: head/share/mk/bsd.sys.mk
===================================================================
--- head/share/mk/bsd.sys.mk
+++ head/share/mk/bsd.sys.mk
@@ -109,6 +109,11 @@
 CWARNFLAGS+=	-Wno-format
 .endif # NO_WFORMAT || NO_WFORMAT.${COMPILER_TYPE}
 
+# GCC 5.2.0
+.if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 50200
+CWARNFLAGS+=	-Wno-error=unused-function -Wno-error=enum-compare -Wno-error=logical-not-parentheses -Wno-error=bool-compare -Wno-error=uninitialized -Wno-error=array-bounds -Wno-error=clobbered -Wno-error=cast-align -Wno-error=extra -Wno-error=attributes -Wno-error=inline -Wno-error=unused-but-set-variable -Wno-error=unused-value -Wno-error=strict-aliasing -Wno-error=address
+.endif
+
 # How to handle FreeBSD custom printf format specifiers.
 .if ${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 30600
 FORMAT_EXTENSIONS=	-D__printf__=__freebsd_kprintf__
Index: head/share/mk/local.meta.sys.mk
===================================================================
--- head/share/mk/local.meta.sys.mk
+++ head/share/mk/local.meta.sys.mk
@@ -48,13 +48,14 @@
 TARGET_ARCHES_mips?=    mipsel mips mips64el mips64 mipsn32 mipsn32el
 TARGET_ARCHES_powerpc?= powerpc powerpc64
 TARGET_ARCHES_pc98?=    i386
+TARGET_ARCHES_riscv?=   riscv64
 
 # some corner cases
 BOOT_MACHINE_DIR.amd64 = boot/i386
 MACHINE_ARCH.host = ${_HOST_ARCH}
 
 # the list of machines we support
-ALL_MACHINE_LIST?= amd64 arm arm64 i386 mips pc98 powerpc sparc64
+ALL_MACHINE_LIST?= amd64 arm arm64 i386 mips pc98 powerpc riscv sparc64
 .for m in ${ALL_MACHINE_LIST:O:u}
 MACHINE_ARCH_LIST.$m?= ${TARGET_ARCHES_${m}:U$m}
 MACHINE_ARCH.$m?= ${MACHINE_ARCH_LIST.$m:[1]}
Index: head/share/mk/src.opts.mk
===================================================================
--- head/share/mk/src.opts.mk
+++ head/share/mk/src.opts.mk
@@ -229,12 +229,17 @@
 __DEFAULT_NO_OPTIONS+=CLANG CLANG_BOOTSTRAP CLANG_FULL CLANG_IS_CC
 .endif
 # In-tree binutils/gcc are older versions without modern architecture support.
-.if ${__T} == "aarch64"
+.if ${__T} == "aarch64" || ${__T} == "riscv64"
 BROKEN_OPTIONS+=BINUTILS BINUTILS_BOOTSTRAP GCC GCC_BOOTSTRAP GDB
 __DEFAULT_YES_OPTIONS+=ELFCOPY_AS_OBJCOPY
 .else
 __DEFAULT_NO_OPTIONS+=ELFCOPY_AS_OBJCOPY
 .endif
+.if ${__T} == "riscv64"
+BROKEN_OPTIONS+=PROFILE # "sorry, unimplemented: profiler support for RISC-V"
+BROKEN_OPTIONS+=TESTS   # "undefined reference to `_Unwind_Resume'"
+BROKEN_OPTIONS+=CXX     # "libcxxrt.so: undefined reference to `_Unwind_Resume_or_Rethrow'"
+.endif
 # LLVM lacks support for FreeBSD 64-bit atomic operations for ARMv4/ARMv5
 .if ${__T} == "arm" || ${__T} == "armeb"
 BROKEN_OPTIONS+=LLDB
Index: head/share/mk/sys.mk
===================================================================
--- head/share/mk/sys.mk
+++ head/share/mk/sys.mk
@@ -13,7 +13,7 @@
 # and/or endian.  This is called MACHINE_CPU in NetBSD, but that's used
 # for something different in FreeBSD.
 #
-MACHINE_CPUARCH=${MACHINE_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb|hf)?/arm/:C/powerpc64/powerpc/}
+MACHINE_CPUARCH=${MACHINE_ARCH:C/mips(n32|64)?(el)?/mips/:C/arm(v6)?(eb|hf)?/arm/:C/powerpc64/powerpc/:C/riscv64/riscv/}
 .endif