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diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetLdtr.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetLdtr.asm
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+++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetLdtr.asm
@@ -0,0 +1,91 @@
+; $Id: bs3-cmn-RegSetLdtr.asm $
+;; @file
+; BS3Kit - Bs3RegSetLdtr
+;
+
+;
+; Copyright (C) 2007-2023 Oracle and/or its affiliates.
+;
+; This file is part of VirtualBox base platform packages, as
+; available from https://www.virtualbox.org.
+;
+; 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, in version 3 of the
+; License.
+;
+; 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 <https://www.gnu.org/licenses>.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+; in the VirtualBox distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+;
+
+%include "bs3kit-template-header.mac"
+
+
+BS3_EXTERN_CMN Bs3Syscall
+%if TMPL_BITS == 16
+BS3_EXTERN_DATA16 g_bBs3CurrentMode
+%endif
+BS3_EXTERN_SYSTEM16 Bs3Gdt
+TMPL_BEGIN_TEXT
+
+
+;;
+; @cproto BS3_CMN_PROTO_STUB(void, Bs3RegSetLdtr,(uint16_t uValue));
+;
+; @param uValue The value to set.
+
+; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
+;
+; @uses No GPRs.
+;
+BS3_PROC_BEGIN_CMN Bs3RegSetLdtr, BS3_PBC_HYBRID_SAFE
+ BS3_CALL_CONV_PROLOG 1
+ push xBP
+ mov xBP, xSP
+ push xDX
+ push xAX
+
+ mov dx, [xBP + xCB + cbCurRetAddr]
+
+%if TMPL_BITS == 16
+ ; If V8086 mode we have to go thru a syscall.
+ test byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], BS3_MODE_CODE_V86
+ jnz .via_system_call
+%endif
+ ; If not in ring-0, we have to make a system call.
+ mov ax, ss
+ and ax, X86_SEL_RPL
+ jnz .via_system_call
+
+ ; Load it.
+ lldt dx
+ jmp .return
+
+.via_system_call:
+ mov ax, BS3_SYSCALL_SET_LDTR
+ call Bs3Syscall
+
+.return:
+ pop xAX
+ pop xDX
+ pop xBP
+ BS3_CALL_CONV_EPILOG 1
+ BS3_HYBRID_RET
+BS3_PROC_END_CMN Bs3RegSetLdtr
+