1 files changed, 96 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetDr0.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetDr0.asm
new file mode 100644
index 00000000..704d6f31
--- /dev/null
+++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-RegSetDr0.asm
@@ -0,0 +1,96 @@
+; $Id: bs3-cmn-RegSetDr0.asm $
+;; @file
+; BS3Kit - Bs3RegSetDr0
+;
+
+;
+; 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
+TMPL_BEGIN_TEXT
+
+
+;;
+; @cproto   BS3_CMN_PROTO_STUB(void, Bs3RegSetDr0,(RTCCUINTXREG 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 Bs3RegSetDr0, BS3_PBC_HYBRID_SAFE
+        BS3_CALL_CONV_PROLOG 1
+        push    xBP
+        mov     xBP, xSP
+        push    sSI
+
+%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
+        cmp     byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], BS3_MODE_RM
+        je      .direct_access
+%endif
+        ; If not in ring-0, we have to make a system call.
+        mov     si, ss
+        and     si, X86_SEL_RPL
+        jnz     .via_system_call
+
+.direct_access:
+        mov     sSI, [xBP + xCB + cbCurRetAddr]
+        mov     dr0, sSI
+        jmp     .return
+
+.via_system_call:
+        push    xDX
+        push    xAX
+
+        mov     sSI, [xBP + xCB + cbCurRetAddr]
+        mov     xAX, BS3_SYSCALL_SET_DRX
+        mov     dl, 0
+        call    Bs3Syscall
+        pop     xAX
+        pop     xDX
+
+.return:
+        pop     sSI
+        pop     xBP
+        BS3_CALL_CONV_EPILOG 1
+        BS3_HYBRID_RET
+BS3_PROC_END_CMN   Bs3RegSetDr0
+