Start support for the RISC-V 64-bit architecture developed by UC Berkeley.

RISC-V is a new ISA designed to support computer research and education, and
is now become a standard open architecture for industry implementations.

This is a minimal set of changes required to run 'make kernel-toolchain'
using external (GNU) toolchain.

The FreeBSD/RISC-V project home: https://wiki.freebsd.org/riscv.

Reviewed by:	andrew, bdrewery, emaste, imp
Sponsored by:	DARPA, AFRL
Sponsored by:	HEIF5
Differential Revision:	https://reviews.freebsd.org/D4445

17 files changed, 560 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index d4d5aa2..0093fb3 100644
--- a/Makefile
+++ b/Makefile
@@ -180,7 +180,7 @@ _MAKE=	PATH=${PATH} ${SUB_MAKE} -f Makefile.inc1 TARGET=${_TARGET} TARGET_ARCH=$
 _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}
diff --git a/Makefile.inc1 b/Makefile.inc1
index 645167b..11fc0b9 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -172,7 +172,11 @@ VERSION=	FreeBSD ${REVISION}-${BRANCH:C/-p[0-9]+$//} ${TARGET_ARCH} ${SRCRELDATE
 .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
diff --git a/etc/etc.riscv/ttys b/etc/etc.riscv/ttys
new file mode 100644
index 0000000..ede1d79
--- /dev/null
+++ b/etc/etc.riscv/ttys
@@ -0,0 +1,51 @@
+#
+# $FreeBSD$
+#	@(#)ttys	5.1 (Berkeley) 4/17/89
+#
+# This file specifies various information about terminals on the system.
+# It is used by several different programs.  Common entries for the
+# various columns include:
+#
+# name  The name of the terminal device.
+#
+# getty The program to start running on the terminal.  Typically a
+#       getty program, as the name implies.  Other common entries
+#       include none, when no getty is needed, and xdm, to start the
+#       X Window System.
+#
+# type The initial terminal type for this port.  For hardwired
+#      terminal lines, this will contain the type of terminal used.
+#      For virtual consoles, the correct type is typically xterm.
+#      Other common values include dialup for incoming modem ports, and
+#      unknown when the terminal type cannot be predetermined.
+#
+# status Must be on or off.  If on, init will run the getty program on
+#        the specified port.  If the word "secure" appears, this tty
+#        allows root login.
+#
+# name	getty				type	status		comments
+#
+# If console is marked "insecure", then init will ask for the root password
+# when going to single-user mode.
+console	none				unknown	off secure
+#
+ttyv0	"/usr/libexec/getty Pc"		xterm	onifconsole  secure
+# Virtual terminals
+ttyv1	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv2	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv3	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv4	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv5	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv6	"/usr/libexec/getty Pc"		xterm	off  secure
+ttyv7	"/usr/libexec/getty Pc"		xterm	off  secure
+#ttyv8	"/usr/local/bin/xdm -nodaemon"	xterm	off secure
+# Serial terminals
+# The 'dialup' keyword identifies dialin lines to login, fingerd etc.
+ttyu0	"/usr/libexec/getty 3wire"	vt100	onifconsole  secure
+ttyu1	"/usr/libexec/getty 3wire"	vt100	onifconsole  secure
+ttyu2	"/usr/libexec/getty 3wire"	vt100	onifconsole  secure
+ttyu3	"/usr/libexec/getty 3wire"	vt100	onifconsole  secure
+# Dumb console
+dcons	"/usr/libexec/getty std.9600"	vt100	off secure
+# RISC-V HTIF console
+rcons	"/usr/libexec/getty std.9600"	vt100	onifconsole  secure
diff --git a/lib/csu/riscv/Makefile b/lib/csu/riscv/Makefile
new file mode 100644
index 0000000..9747619
--- /dev/null
+++ b/lib/csu/riscv/Makefile
@@ -0,0 +1,46 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../common
+
+SRCS=		crt1.c crti.S crtn.S
+OBJS=		${SRCS:N*.h:R:S/$/.o/g}
+OBJS+=		Scrt1.o gcrt1.o
+CFLAGS+=	-I${.CURDIR}/../common \
+		-I${.CURDIR}/../../libc/include
+
+FILES=		${OBJS}
+FILESMODE=	${LIBMODE}
+FILESOWN=	${LIBOWN}
+FILESGRP=	${LIBGRP}
+FILESDIR=	${LIBDIR}
+# These FILES qualify as libraries for the purpose of LIBRARIES_ONLY.
+.undef LIBRARIES_ONLY
+
+CLEANFILES=	${OBJS}
+CLEANFILES+=	crt1.s gcrt1.s Scrt1.s
+
+# See the comment in lib/csu/common/crtbrand.c for the reason crt1.c is not
+# directly compiled to .o files.
+
+crt1.s: crt1.c
+	${CC} ${CFLAGS} -S -o ${.TARGET} ${.CURDIR}/crt1.c
+	sed ${SED_FIX_NOTE} ${.TARGET}
+
+crt1.o: crt1.s
+	${CC} ${ACFLAGS} -c -o ${.TARGET} crt1.s
+
+gcrt1.s: crt1.c
+	${CC} ${CFLAGS} -DGCRT -S -o ${.TARGET} ${.CURDIR}/crt1.c
+	sed ${SED_FIX_NOTE} ${.TARGET}
+
+gcrt1.o: gcrt1.s
+	${CC} ${ACFLAGS} -c -o ${.TARGET} gcrt1.s
+
+Scrt1.s: crt1.c
+	${CC} ${CFLAGS} -fPIC -DPIC -S -o ${.TARGET} ${.CURDIR}/crt1.c
+	sed ${SED_FIX_NOTE} ${.TARGET}
+
+Scrt1.o: Scrt1.s
+	${CC} ${ACFLAGS} -c -o ${.TARGET} Scrt1.s
+
+.include <bsd.lib.mk>
diff --git a/lib/csu/riscv/crt1.c b/lib/csu/riscv/crt1.c
new file mode 100644
index 0000000..0c3fbe6
--- /dev/null
+++ b/lib/csu/riscv/crt1.c
@@ -0,0 +1,89 @@
+/* LINTLIBRARY */
+/*-
+ * Copyright 1996-1998 John D. Polstra.
+ * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
+ * All rights reserved.
+ *
+ * Portions of this software were developed by SRI International and the
+ * University of Cambridge Computer Laboratory under DARPA/AFRL contract
+ * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Portions of this software were developed by the University of Cambridge
+ * Computer Laboratory as part of the CTSRD Project, with support from the
+ * UK Higher Education Innovation Fund (HEIF).
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <stdlib.h>
+
+#include "libc_private.h"
+#include "crtbrand.c"
+#include "ignore_init.c"
+
+typedef void (*fptr)(void);
+
+#ifdef GCRT
+extern void _mcleanup(void);
+extern void monstartup(void *, void *);
+extern int eprol;
+extern int etext;
+#endif
+
+void __start(int argc, char **argv, char **env, void (*cleanup)(void));
+
+/* The entry function. */
+__asm("	.text			\n"
+"	.align 0		\n"
+"	.globl _start		\n"
+"	_start:			\n"
+"	mv	a3, a2		\n" /* cleanup */
+"	addi	a1, a0, 8	\n" /* get argv */
+"	ld	a0, 0(a0)	\n" /* load argc */
+"	slli	t0, a0, 3	\n" /* mult by arg size */
+"	add	a2, a1, t0	\n" /* env is after argv */
+"	addi	a2, a2, 8	\n" /* argv is null terminated */
+"	lla	gp, _gp		\n" /* load global pointer */
+"	call	__start");
+
+void
+__start(int argc, char **argv, char **env, void (*cleanup)(void))
+{
+
+	handle_argv(argc, argv, env);
+
+	if (&_DYNAMIC != NULL)
+		atexit(cleanup);
+	else
+		_init_tls();
+
+#ifdef GCRT
+	atexit(_mcleanup);
+	monstartup(&eprol, &etext);
+__asm__("eprol:");
+#endif
+
+	handle_static_init(argc, argv, env);
+	exit(main(argc, argv, env));
+}
diff --git a/lib/csu/riscv/crti.S b/lib/csu/riscv/crti.S
new file mode 100644
index 0000000..df6027e
--- /dev/null
+++ b/lib/csu/riscv/crti.S
@@ -0,0 +1,58 @@
+/*-
+ * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
+ * All rights reserved.
+ *
+ * Portions of this software were developed by SRI International and the
+ * University of Cambridge Computer Laboratory under DARPA/AFRL contract
+ * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Portions of this software were developed by the University of Cambridge
+ * Computer Laboratory as part of the CTSRD Project, with support from the
+ * UK Higher Education Innovation Fund (HEIF).
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+# this puts _gp into .dynsym, so symlook_obj can now find that (see reloc.c)
+	.weak	_gp
+_gp:
+
+	.section .init,"ax",@progbits
+	.align	2
+	.globl	_init
+	.type	_init,@function
+_init:
+	addi	sp, sp, -16
+	sd	ra, 0(sp)
+
+	.section .fini,"ax",@progbits
+	.align	2
+	.globl	_fini
+	.type	_fini,@function
+_fini:
+	addi	sp, sp, -16
+	sd	ra, 0(sp)
+
+	.section .note.GNU-stack,"",%progbits
diff --git a/lib/csu/riscv/crtn.S b/lib/csu/riscv/crtn.S
new file mode 100644
index 0000000..b582471
--- /dev/null
+++ b/lib/csu/riscv/crtn.S
@@ -0,0 +1,48 @@
+/*-
+ * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
+ * All rights reserved.
+ *
+ * Portions of this software were developed by SRI International and the
+ * University of Cambridge Computer Laboratory under DARPA/AFRL contract
+ * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Portions of this software were developed by the University of Cambridge
+ * Computer Laboratory as part of the CTSRD Project, with support from the
+ * UK Higher Education Innovation Fund (HEIF).
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <machine/asm.h>
+__FBSDID("$FreeBSD$");
+
+	.section .init,"ax",@progbits
+	ld	ra, 0(sp)
+	addi	sp, sp, 16
+	ret
+
+	.section .fini,"ax",@progbits
+	ld	ra, 0(sp)
+	addi	sp, sp, 16
+	ret
+
+	.section .note.GNU-stack,"",%progbits
diff --git a/lib/libc/riscv/Makefile.inc b/lib/libc/riscv/Makefile.inc
new file mode 100644
index 0000000..e8c0da7
--- /dev/null
+++ b/lib/libc/riscv/Makefile.inc
@@ -0,0 +1 @@
+# $FreeBSD$
diff --git a/lib/libthr/arch/riscv/Makefile.inc b/lib/libthr/arch/riscv/Makefile.inc
new file mode 100644
index 0000000..e8c0da7
--- /dev/null
+++ b/lib/libthr/arch/riscv/Makefile.inc
@@ -0,0 +1 @@
+# $FreeBSD$
diff --git a/lib/msun/riscv/Makefile.inc b/lib/msun/riscv/Makefile.inc
new file mode 100644
index 0000000..0ce69db
--- /dev/null
+++ b/lib/msun/riscv/Makefile.inc
@@ -0,0 +1,6 @@
+# $FreeBSD$
+
+# RISCVTODO: should be 113
+# compilation problems: gcc generates bltuz instruction, which is not exists
+
+LDBL_PREC = 53
diff --git a/lib/msun/riscv/fenv.h b/lib/msun/riscv/fenv.h
new file mode 100644
index 0000000..3eae6c2
--- /dev/null
+++ b/lib/msun/riscv/fenv.h
@@ -0,0 +1,228 @@
+/*-
+ * Copyright (c) 2004-2005 David Schultz <das@FreeBSD.ORG>
+ * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
+ * All rights reserved.
+ *
+ * Portions of this software were developed by SRI International and the
+ * University of Cambridge Computer Laboratory under DARPA/AFRL contract
+ * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
+ *
+ * Portions of this software were developed by the University of Cambridge
+ * Computer Laboratory as part of the CTSRD Project, with support from the
+ * UK Higher Education Innovation Fund (HEIF).
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_FENV_H_
+#define	_FENV_H_
+
+#include <sys/_types.h>
+
+#ifndef	__fenv_static
+#define	__fenv_static	static
+#endif
+
+typedef	__uint64_t	fenv_t;
+typedef	__uint64_t	fexcept_t;
+
+/* Exception flags */
+#define	FE_INVALID	0x0010
+#define	FE_DIVBYZERO	0x0008
+#define	FE_OVERFLOW	0x0004
+#define	FE_UNDERFLOW	0x0002
+#define	FE_INEXACT	0x0001
+#define	FE_ALL_EXCEPT	(FE_DIVBYZERO | FE_INEXACT | \
+			 FE_INVALID | FE_OVERFLOW | FE_UNDERFLOW)
+
+/*
+ * RISC-V Rounding modes
+ */
+#define	FE_TONEAREST	(0x00 << 5)
+#define	FE_TOWARDZERO	(0x01 << 5)
+#define	FE_DOWNWARD	(0x02 << 5)
+#define	FE_UPWARD	(0x03 << 5)
+#define	_ROUND_SHIFT	5
+#define	_ROUND_MASK	(FE_TONEAREST | FE_DOWNWARD | \
+			 FE_UPWARD | FE_TOWARDZERO)
+
+__BEGIN_DECLS
+
+/* Default floating-point environment */
+extern const fenv_t	__fe_dfl_env;
+#define	FE_DFL_ENV	(&__fe_dfl_env)
+
+/* We need to be able to map status flag positions to mask flag positions */
+#define	_FPUSW_SHIFT	0
+#define	_ENABLE_MASK	(FE_ALL_EXCEPT << _FPUSW_SHIFT)
+
+#define	__rfs(__fpsr)	__asm __volatile("csrr %0, fcsr" : "=r" (*(__fpsr)))
+#define	__wfs(__fpsr)	__asm __volatile("csrw fcsr, %0" :: "r" (__fpsr))
+
+__fenv_static inline int
+feclearexcept(int __excepts)
+{
+	fexcept_t __fpsr;
+
+	__rfs(&__fpsr);
+	__fpsr &= ~__excepts;
+	__wfs(__fpsr);
+	return (0);
+}
+
+__fenv_static inline int
+fegetexceptflag(fexcept_t *__flagp, int __excepts)
+{
+	fexcept_t __fpsr;
+
+	__rfs(&__fpsr);
+	*__flagp = __fpsr & __excepts;
+	return (0);
+}
+
+__fenv_static inline int
+fesetexceptflag(const fexcept_t *__flagp, int __excepts)
+{
+	fexcept_t __fpsr;
+
+	__rfs(&__fpsr);
+	__fpsr &= ~__excepts;
+	__fpsr |= *__flagp & __excepts;
+	__wfs(__fpsr);
+	return (0);
+}
+
+__fenv_static inline int
+feraiseexcept(int __excepts)
+{
+	fexcept_t __ex = __excepts;
+
+	fesetexceptflag(&__ex, __excepts);	/* XXX */
+	return (0);
+}
+
+__fenv_static inline int
+fetestexcept(int __excepts)
+{
+	fexcept_t __fpsr;
+
+	__rfs(&__fpsr);
+	return (__fpsr & __excepts);
+}
+
+__fenv_static inline int
+fegetround(void)
+{
+
+	return (-1);
+}
+
+__fenv_static inline int
+fesetround(int __round)
+{
+
+	return (-1);
+}
+
+__fenv_static inline int
+fegetenv(fenv_t *__envp)
+{
+
+	__rfs(__envp);
+	return (0);
+}
+
+__fenv_static inline int
+feholdexcept(fenv_t *__envp)
+{
+	fenv_t __env;
+
+	__rfs(&__env);
+	*__envp = __env;
+	__env &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
+	__wfs(__env);
+	return (0);
+}
+
+__fenv_static inline int
+fesetenv(const fenv_t *__envp)
+{
+
+	__wfs(*__envp);
+	return (0);
+}
+
+__fenv_static inline int
+feupdateenv(const fenv_t *__envp)
+{
+	fexcept_t __fpsr;
+
+	__rfs(&__fpsr);
+	__wfs(*__envp);
+	feraiseexcept(__fpsr & FE_ALL_EXCEPT);
+	return (0);
+}
+
+#if __BSD_VISIBLE
+
+/* We currently provide no external definitions of the functions below. */
+
+static inline int
+feenableexcept(int __mask)
+{
+	fenv_t __old_fpsr;
+	fenv_t __new_fpsr;
+
+	__rfs(&__old_fpsr);
+	__new_fpsr = __old_fpsr | (__mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT;
+	__wfs(__new_fpsr);
+	return ((__old_fpsr >> _FPUSW_SHIFT) & FE_ALL_EXCEPT);
+}
+
+static inline int
+fedisableexcept(int __mask)
+{
+	fenv_t __old_fpsr;
+	fenv_t __new_fpsr;
+
+	__rfs(&__old_fpsr);
+	__new_fpsr = __old_fpsr & ~((__mask & FE_ALL_EXCEPT) << _FPUSW_SHIFT);
+	__wfs(__new_fpsr);
+	return ((__old_fpsr >> _FPUSW_SHIFT) & FE_ALL_EXCEPT);
+}
+
+static inline int
+fegetexcept(void)
+{
+	fenv_t __fpsr;
+
+	__rfs(&__fpsr);
+	return ((__fpsr & _ENABLE_MASK) >> _FPUSW_SHIFT);
+}
+
+#endif /* __BSD_VISIBLE */
+
+__END_DECLS
+
+#endif	/* !_FENV_H_ */
diff --git a/share/mk/bsd.cpu.mk b/share/mk/bsd.cpu.mk
index 1ab7595..d54a354 100644
--- a/share/mk/bsd.cpu.mk
+++ b/share/mk/bsd.cpu.mk
@@ -18,6 +18,8 @@ MACHINE_CPU = i486
 MACHINE_CPU = mips
 . elif ${MACHINE_CPUARCH} == "powerpc"
 MACHINE_CPU = aim
+. elif ${MACHINE_CPUARCH} == "riscv"
+MACHINE_CPU = riscv
 . elif ${MACHINE_CPUARCH} == "sparc64"
 MACHINE_CPU = ultrasparc
 . endif
@@ -148,6 +150,8 @@ _CPUCFLAGS = -march=${CPUTYPE}
 #	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 @@ MACHINE_CPU = mips
 .  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 @@ CFLAGS += -mfloat-abi=softfp
 .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)
diff --git a/share/mk/bsd.endian.mk b/share/mk/bsd.endian.mk
index 2d1a53e..c7ec42c 100644
--- a/share/mk/bsd.endian.mk
+++ b/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 ${MACHINE_ARCH} == "powerpc" || \
diff --git a/share/mk/bsd.sys.mk b/share/mk/bsd.sys.mk
index 6eae174..de62195 100644
--- a/share/mk/bsd.sys.mk
+++ b/share/mk/bsd.sys.mk
@@ -109,6 +109,11 @@ CWARNFLAGS+=	-Werror
 CWARNFLAGS+=	-Wno-format
 .endif # NO_WFORMAT || NO_WFORMAT.${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__
diff --git a/share/mk/local.meta.sys.mk b/share/mk/local.meta.sys.mk
index a97f6f2..1aa749a 100644
--- a/share/mk/local.meta.sys.mk
+++ b/share/mk/local.meta.sys.mk
@@ -48,13 +48,14 @@ TARGET_ARCHES_arm64?=   aarch64
 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]}
diff --git a/share/mk/src.opts.mk b/share/mk/src.opts.mk
index 094019d..f94e63a 100644
--- a/share/mk/src.opts.mk
+++ b/share/mk/src.opts.mk
@@ -229,12 +229,17 @@ __DEFAULT_YES_OPTIONS+=GCC GCC_BOOTSTRAP GNUCXX
 __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" || ${__T} == "armeb"
 BROKEN_OPTIONS+=LLDB
diff --git a/share/mk/sys.mk b/share/mk/sys.mk
index f9ac418..8fe6b68 100644
--- a/share/mk/sys.mk
+++ b/share/mk/sys.mk
@@ -13,7 +13,7 @@ unix		?=	We run FreeBSD, not UNIX.
 # and/or endian.  This is called MACHINE_CPU in NetBSD, but that's used
 # for something different in FreeBSD.
 #
-MACHINE_CPUARCH=${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