Index: head/sys/conf/files.riscv
===================================================================
--- head/sys/conf/files.riscv
+++ head/sys/conf/files.riscv
@@ -55,6 +55,7 @@
 riscv/riscv/plic.c		standard
 riscv/riscv/pmap.c		standard
 riscv/riscv/riscv_console.c	optional	rcons
+riscv/riscv/sbi.c		standard
 riscv/riscv/soc.c		standard
 riscv/riscv/stack_machdep.c	optional	ddb | stack
 riscv/riscv/support.S		standard
Index: head/sys/riscv/riscv/identcpu.c
===================================================================
--- head/sys/riscv/riscv/identcpu.c
+++ head/sys/riscv/riscv/identcpu.c
@@ -60,6 +60,11 @@
 SYSCTL_STRING(_hw, HW_MACHINE, machine, CTLFLAG_RD, machine, 0,
     "Machine class");
 
+/* Hardware implementation info. These values may be empty. */
+register_t mvendorid;	/* The CPU's JEDEC vendor ID */
+register_t marchid;	/* The architecture ID */
+register_t mimpid;	/* The implementation ID */
+
 struct cpu_desc {
 	u_int		cpu_impl;
 	u_int		cpu_part_num;
Index: head/sys/riscv/riscv/machdep.c
===================================================================
--- head/sys/riscv/riscv/machdep.c
+++ head/sys/riscv/riscv/machdep.c
@@ -850,6 +850,9 @@
 
 	PCPU_SET(curthread, &thread0);
 
+	/* Initialize SBI interface. */
+	sbi_init();
+
 	/* Set the module data location */
 	lastaddr = fake_preload_metadata(rvbp);
 
Index: head/sys/riscv/riscv/sbi.c
===================================================================
--- head/sys/riscv/riscv/sbi.c
+++ head/sys/riscv/riscv/sbi.c
@@ -0,0 +1,127 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Mitchell Horne <mhorne@FreeBSD.org>
+ *
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/types.h>
+
+#include <machine/md_var.h>
+#include <machine/sbi.h>
+
+u_long sbi_spec_version;
+u_long sbi_impl_id;
+u_long sbi_impl_version;
+
+static struct sbi_ret
+sbi_get_spec_version(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_SPEC_VERSION));
+}
+
+static struct sbi_ret
+sbi_get_impl_id(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_IMPL_ID));
+}
+
+static struct sbi_ret
+sbi_get_impl_version(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_IMPL_VERSION));
+}
+
+static struct sbi_ret
+sbi_get_mvendorid(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_MVENDORID));
+}
+
+
+static struct sbi_ret
+sbi_get_marchid(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_MARCHID));
+}
+
+static struct sbi_ret
+sbi_get_mimpid(void)
+{
+	return (SBI_CALL0(SBI_EXT_ID_BASE, SBI_BASE_GET_MIMPID));
+}
+
+void
+sbi_init(void)
+{
+	struct sbi_ret sret;
+
+	/*
+	 * Get the spec version. For legacy SBI implementations this will
+	 * return an error, otherwise it is guaranteed to succeed.
+	 */
+	sret = sbi_get_spec_version();
+	if (sret.error != 0) {
+		/* We are running a legacy SBI implementation. */
+		sbi_spec_version = 0;
+		return;
+	}
+
+	/* Set the SBI implementation info. */
+	sbi_spec_version = sret.value;
+	sbi_impl_id = sbi_get_impl_id().value;
+	sbi_impl_version = sbi_get_impl_version().value;
+
+	/* Set the hardware implementation info. */
+	mvendorid = sbi_get_mvendorid().value;
+	marchid = sbi_get_marchid().value;
+	mimpid = sbi_get_mimpid().value;
+
+	/*
+	 * Probe for legacy extensions. Currently we rely on all of them
+	 * to be implemented, but this is not guaranteed by the spec.
+	 */
+	KASSERT(sbi_probe_extension(SBI_SET_TIMER) != 0,
+	    ("SBI doesn't implement sbi_set_timer()"));
+	KASSERT(sbi_probe_extension(SBI_CONSOLE_PUTCHAR) != 0,
+	    ("SBI doesn't implement sbi_console_putchar()"));
+	KASSERT(sbi_probe_extension(SBI_CONSOLE_GETCHAR) != 0,
+	    ("SBI doesn't implement sbi_console_getchar()"));
+	KASSERT(sbi_probe_extension(SBI_CLEAR_IPI) != 0,
+	    ("SBI doesn't implement sbi_clear_ipi()"));
+	KASSERT(sbi_probe_extension(SBI_SEND_IPI) != 0,
+	    ("SBI doesn't implement sbi_send_ipi()"));
+	KASSERT(sbi_probe_extension(SBI_REMOTE_FENCE_I) != 0,
+	    ("SBI doesn't implement sbi_remote_fence_i()"));
+	KASSERT(sbi_probe_extension(SBI_REMOTE_SFENCE_VMA) != 0,
+	    ("SBI doesn't implement sbi_remote_sfence_vma()"));
+	KASSERT(sbi_probe_extension(SBI_REMOTE_SFENCE_VMA_ASID) != 0,
+	    ("SBI doesn't implement sbi_remote_sfence_vma_asid()"));
+	KASSERT(sbi_probe_extension(SBI_SHUTDOWN) != 0,
+	    ("SBI doesn't implement sbi_shutdown()"));
+}