Index: gcc-8.0.1+r257516/libgo/configure.ac
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/configure.ac
+++ gcc-8.0.1+r257516/libgo/configure.ac
@@ -224,10 +224,10 @@ AC_SUBST(USE_DEJAGNU)
 #   - libgo/go/syscall/endian_XX.go
 #   - possibly others
 # - possibly update files in libgo/go/internal/syscall/unix
-ALLGOARCH="386 alpha amd64 amd64p32 arm armbe arm64 arm64be ia64 m68k mips mipsle mips64 mips64le mips64p32 mips64p32le ppc ppc64 ppc64le s390 s390x sh shbe sparc sparc64"
+ALLGOARCH="386 alpha amd64 amd64p32 arm armbe arm64 arm64be ia64 m68k mips mipsle mips64 mips64le mips64p32 mips64p32le ppc ppc64 ppc64le riscv64 s390 s390x sh shbe sparc sparc64"
 
 # All known GOARCH family values.
-ALLGOARCHFAMILY="I386 ALPHA AMD64 ARM ARM64 IA64 M68K MIPS MIPS64 PPC PPC64 S390 S390X SH SPARC SPARC64"
+ALLGOARCHFAMILY="I386 ALPHA AMD64 ARM ARM64 IA64 M68K MIPS MIPS64 PPC PPC64 RISCV64 S390 S390X SH SPARC SPARC64"
 
 GOARCH=unknown
 case ${host} in
@@ -304,6 +304,9 @@ AC_COMPILE_IFELSE([
 [GOARCH=ppc64le],
 [GOARCH=ppc64])])
     ;;
+  riscv64-*-*)
+    GOARCH=riscv64
+    ;;
   s390*-*-*)
     AC_COMPILE_IFELSE([
 #if defined(__s390x__)
@@ -500,7 +503,8 @@ AC_COMPILE_IFELSE([[int i;]],
 CFLAGS=$CFLAGS_hold])
 PTHREAD_CFLAGS=
 if test "$libgo_cv_lib_pthread" = yes; then
-  PTHREAD_CFLAGS=-pthread
+  # RISC-V apparently adds -latomic when using -pthread.
+  PTHREAD_CFLAGS="-pthread -L../libatomic/.libs"
 fi
 AC_SUBST(PTHREAD_CFLAGS)
 
Index: gcc-8.0.1+r257516/libgo/go/cmd/cgo/main.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/cmd/cgo/main.go
+++ gcc-8.0.1+r257516/libgo/go/cmd/cgo/main.go
@@ -168,6 +168,7 @@ var ptrSizeMap = map[string]int64{
 	"ppc":         4,
 	"ppc64":       8,
 	"ppc64le":     8,
+	"riscv64":     8,
 	"s390":        4,
 	"s390x":       8,
 	"sh":          4,
@@ -192,6 +193,7 @@ var intSizeMap = map[string]int64{
 	"ppc":         4,
 	"ppc64":       8,
 	"ppc64le":     8,
+	"riscv64":     8,
 	"s390":        4,
 	"s390x":       8,
 	"sh":          4,
Index: gcc-8.0.1+r257516/libgo/go/go/build/syslist.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/go/build/syslist.go
+++ gcc-8.0.1+r257516/libgo/go/go/build/syslist.go
@@ -5,4 +5,4 @@
 package build
 
 const goosList = "aix android darwin dragonfly freebsd linux nacl netbsd openbsd plan9 solaris windows zos "
-const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be alpha m68k ppc64 ppc64le mips mipsle mips64 mips64le mips64p32 mips64p32le ppc s390 s390x sh shbe sparc sparc64"
+const goarchList = "386 amd64 amd64p32 arm armbe arm64 arm64be alpha m68k ppc64 ppc64le mips mipsle mips64 mips64le mips64p32 mips64p32le ppc riscv64 s390 s390x sh shbe sparc sparc64"
Index: gcc-8.0.1+r257516/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
+++ gcc-8.0.1+r257516/libgo/go/internal/syscall/unix/getrandom_linux_generic.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build arm64
+// +build arm64 riscv64
 
 package unix
 
Index: gcc-8.0.1+r257516/libgo/go/runtime/hash64.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/runtime/hash64.go
+++ gcc-8.0.1+r257516/libgo/go/runtime/hash64.go
@@ -6,7 +6,7 @@
 //   xxhash: https://code.google.com/p/xxhash/
 // cityhash: https://code.google.com/p/cityhash/
 
-// +build amd64 amd64p32 arm64 mips64 mips64le ppc64 ppc64le s390x alpha arm64be ia64 mips64p32 mips64p32le sparc64
+// +build amd64 amd64p32 arm64 mips64 mips64le ppc64 ppc64le s390x alpha arm64be ia64 mips64p32 mips64p32le sparc64 riscv64
 
 package runtime
 
Index: gcc-8.0.1+r257516/libgo/go/runtime/lfstack_64bit.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/runtime/lfstack_64bit.go
+++ gcc-8.0.1+r257516/libgo/go/runtime/lfstack_64bit.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x arm64be alpha sparc64 ia64
+// +build amd64 arm64 mips64 mips64le ppc64 ppc64le s390x arm64be alpha sparc64 ia64 riscv64
 
 package runtime
 
Index: gcc-8.0.1+r257516/libgo/go/runtime/unaligned1.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/runtime/unaligned1.go
+++ gcc-8.0.1+r257516/libgo/go/runtime/unaligned1.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build 386 amd64 amd64p32 arm64 ppc64 ppc64le s390x ppc s390 arm64be
+// +build 386 amd64 amd64p32 arm64 ppc64 ppc64le s390x ppc s390 arm64be riscv64
 
 package runtime
 
Index: gcc-8.0.1+r257516/libgo/go/syscall/endian_little.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/syscall/endian_little.go
+++ gcc-8.0.1+r257516/libgo/go/syscall/endian_little.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 //
-// +build 386 amd64 amd64p32 arm arm64 ppc64le mips64le mipsle alpha ia64 mips64p32le sh
+// +build 386 amd64 amd64p32 arm arm64 ppc64le mips64le mipsle alpha ia64 mips64p32le sh riscv64
 
 package syscall
 
Index: gcc-8.0.1+r257516/libgo/go/syscall/libcall_linux_ustat.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/go/syscall/libcall_linux_ustat.go
+++ gcc-8.0.1+r257516/libgo/go/syscall/libcall_linux_ustat.go
@@ -4,7 +4,7 @@
 
 // GNU/Linux library ustat call.
 // This is not supported on some kernels, such as arm64.
-// +build !arm64
+// +build !arm64,!riscv64
 
 package syscall
 
Index: gcc-8.0.1+r257516/libgo/goarch.sh
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/goarch.sh
+++ gcc-8.0.1+r257516/libgo/goarch.sh
@@ -146,6 +146,10 @@ case $goarch in
 		;;
 	esac
 	;;
+    riscv64)
+	family=RISCV64
+	pcquantum=2
+	;;
     s390)
 	family=S390
 	bigendian=true
Index: gcc-8.0.1+r257516/libgo/match.sh
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/match.sh
+++ gcc-8.0.1+r257516/libgo/match.sh
@@ -116,7 +116,7 @@ for f in $gofiles; do
 	aix | android | darwin | dragonfly | freebsd | linux | nacl | netbsd | openbsd | plan9 | solaris | windows)
 	    tag1=nonmatchingtag
 	    ;;
-	386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | s390 | s390x | sh | shbe | sparc | sparc64)
+	386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | riscv64 | s390 | s390x | sh | shbe | sparc | sparc64)
 	    tag1=nonmatchingtag
 	    ;;
     esac
@@ -128,7 +128,7 @@ for f in $gofiles; do
 	aix | android | darwin | dragonfly | freebsd | linux | nacl | netbsd | openbsd | plan9 | solaris | windows)
 	    tag2=nonmatchingtag
 	    ;;
-	386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | s390 | s390x | sh | shbe | sparc | sparc64)
+	386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | riscv64 | s390 | s390x | sh | shbe | sparc | sparc64)
 	    tag2=nonmatchingtag
 	    ;;
     esac
Index: gcc-8.0.1+r257516/libgo/misc/cgo/testcshared/src/libgo2/dup2.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/misc/cgo/testcshared/src/libgo2/dup2.go
+++ gcc-8.0.1+r257516/libgo/misc/cgo/testcshared/src/libgo2/dup2.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux,!arm64 netbsd openbsd
+// +build darwin dragonfly freebsd linux,!arm64,!riscv64 netbsd openbsd
 
 package main
 
Index: gcc-8.0.1+r257516/libgo/misc/cgo/testcshared/src/libgo2/dup3.go
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/misc/cgo/testcshared/src/libgo2/dup3.go
+++ gcc-8.0.1+r257516/libgo/misc/cgo/testcshared/src/libgo2/dup3.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build linux,arm64
+// +build linux,arm64 linux,riscv64
 
 package main
 
Index: gcc-8.0.1+r257516/libgo/testsuite/gotest
===================================================================
--- gcc-8.0.1+r257516.orig/libgo/testsuite/gotest
+++ gcc-8.0.1+r257516/libgo/testsuite/gotest
@@ -314,7 +314,7 @@ x)
 	    aix | android | darwin | dragonfly | freebsd | linux | nacl | netbsd | openbsd | plan9 | solaris | windows)
 		tag1=nonmatchingtag
 		;;
-	    386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | s390 | s390x | sh | shbe | sparc | sparc64)
+	    386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | riscv64 | s390 | s390x | sh | shbe | sparc | sparc64)
 		tag1=nonmatchingtag
 		;;
 	    esac
@@ -326,7 +326,7 @@ x)
 	    aix | android | darwin | dragonfly | freebsd | linux | nacl | netbsd | openbsd | plan9 | solaris | windows)
 		tag2=nonmatchingtag
 		;;
-	    386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | s390 | s390x | sh | shbe | sparc | sparc64)
+	    386 | amd64 | amd64p32 | arm | armbe | arm64 | arm64be | alpha | ia64 | m68k | ppc64 | ppc64le | mips | mipsle | mips64 | mips64le | mips64p32 | mips64p32le | ppc | riscv64 | s390 | s390x | sh | shbe | sparc | sparc64)
 		tag2=nonmatchingtag
 		;;
 	    esac
Index: gcc-8.0.1+r257516/gcc/testsuite/go.test/go-test.exp
===================================================================
--- gcc-8.0.1+r257516.orig/gcc/testsuite/go.test/go-test.exp
+++ gcc-8.0.1+r257516/gcc/testsuite/go.test/go-test.exp
@@ -246,6 +246,9 @@ proc go-set-goarch { } {
 		}
 	    }
 	}
+	"riscv64-*-*" {
+	    set goarch "riscv64"
+	}
 	"s390*-*-*" {
 	    if [check_effective_target_ilp32] {
 		set goarch "s390"