Index: gdb/riscv-obsd-tdep.h
--- gdb/riscv-obsd-tdep.h.orig
+++ gdb/riscv-obsd-tdep.h
@@ -0,0 +1,39 @@
+/* OpenBSD/riscv64 target support, prototypes.
+
+   Copyright (C) 2018-2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef RISCV_OBSD_TDEP_H
+#define RISCV_OBSD_TDEP_H
+
+#include "regset.h"
+
+/* The general-purpose regset consists of 31 X registers, EPC, and
+   SSTATUS.  */
+#define RISCV_OBSD_NUM_GREGS		33
+
+/* The fp regset always consists of 32 128-bit registers, plus a
+   64-bit CSR_FCSR.  If 'Q' is not supported, only the low 64-bits of
+   each floating point register are valid.  If 'D' is not supported,
+   only the low 32-bits of each floating point register are valid.  */
+/* XXX on OpenBSD only 64 bits floating point registers are considered. */
+#define RISCV_OBSD_SIZEOF_FPREGSET (32 * 8 + 8)
+
+extern const struct regset riscv_obsd_gregset;
+extern const struct regset riscv_obsd_fpregset;
+
+#endif /* RISCV_OBSD_TDEP_H */