diff --git a/sys/arm64/arm64/sys_machdep.c b/sys/arm64/arm64/sys_machdep.c
index eedc57f7c572..81b8ef73d9c0 100644
--- a/sys/arm64/arm64/sys_machdep.c
+++ b/sys/arm64/arm64/sys_machdep.c
@@ -1,82 +1,95 @@
 /*-
  * Copyright (c) 2015 The FreeBSD Foundation
  *
  * This software was developed by Andrew Turner under
  * sponsorship from the FreeBSD Foundation.
  *
  * 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/param.h>
+#include <sys/proc.h>
 #include <sys/systm.h>
 #include <sys/proc.h>
 #include <sys/sysproto.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 
+#include <machine/pcb.h>
 #include <machine/sysarch.h>
 #include <machine/vmparam.h>
 
+#include <security/audit/audit.h>
+
 int
 sysarch(struct thread *td, struct sysarch_args *uap)
 {
 	struct arm64_guard_page_args gp_args;
+	struct pcb *pcb;
 	vm_offset_t eva;
+	unsigned long sve_len;
 	int error;
 
 	switch (uap->op) {
 	case ARM64_GUARD_PAGE:
 		error = copyin(uap->parms, &gp_args, sizeof(gp_args));
 		if (error != 0)
 			return (error);
 
 		/* Only accept canonical addresses, no PAC or TBI */
 		if (!ADDR_IS_CANONICAL(gp_args.addr))
 			return (EINVAL);
 
 		eva = gp_args.addr + gp_args.len;
 
 		/* Check for a length overflow */
 		if (gp_args.addr > eva)
 			return (EINVAL);
 
 		/* Check in the correct address space */
 		if (eva >= VM_MAX_USER_ADDRESS)
 			return (EINVAL);
 
 		/* Nothing to do */
 		if (gp_args.len == 0)
 			return (0);
 
 		error = pmap_bti_set(vmspace_pmap(td->td_proc->p_vmspace),
 		    trunc_page(gp_args.addr), round_page(eva));
 		break;
+	case ARM64_GET_SVE_VL:
+		pcb = td->td_pcb;
+		sve_len = pcb->pcb_sve_len;
+		error = EINVAL;
+		if (sve_len != 0)
+			error = copyout(&sve_len, uap->parms, sizeof(sve_len));
+		break;
 	default:
 		error = EINVAL;
 		break;
 	}
 
 	return (error);
 }
diff --git a/sys/arm64/include/sysarch.h b/sys/arm64/include/sysarch.h
index 83094943423a..b7846651c031 100644
--- a/sys/arm64/include/sysarch.h
+++ b/sys/arm64/include/sysarch.h
@@ -1,59 +1,62 @@
 /*-
  * Copyright (c) 1993 The Regents of the University of California.
  * All rights reserved.
  *
  * 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.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
  *
  *	from: FreeBSD: src/sys/i386/include/sysarch.h,v 1.14 2000/09/21
  */
 
 #ifdef __arm__
 #include <arm/sysarch.h>
 #else /* !__arm__ */
 
 /*
  * Architecture specific syscalls (arm64)
  */
 #ifndef _MACHINE_SYSARCH_H_
 #define	_MACHINE_SYSARCH_H_
 
 #define	ARM64_GUARD_PAGE	0x100
 
 struct arm64_guard_page_args {
 	__uintptr_t	addr;
 	__size_t	len;
 };
 
+#define	ARM64_GET_SVE_VL	0x200
+/* Reserved ARM64_SET_SVE_VL	0x201 */
+
 #ifndef _KERNEL
 
 __BEGIN_DECLS
 int	sysarch(int _number, void *_args);
 __END_DECLS
 
 #endif
 
 #endif /* !_MACHINE_SYSARCH_H_ */
 
 #endif /* !__arm__ */