VirtualBox

source: vbox/trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm@ 102157

Last change on this file since 102157 was 98103, checked in by vboxsync, 2 years ago

Copyright year updates by scm.

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1; $Id: bs3-cmn-A20Enable.asm 98103 2023-01-17 14:15:46Z vboxsync $
2;; @file
3; BS3Kit - Bs3A20Enable.
4;
5
6;
7; Copyright (C) 2007-2023 Oracle and/or its affiliates.
8;
9; This file is part of VirtualBox base platform packages, as
10; available from https://www.virtualbox.org.
11;
12; This program is free software; you can redistribute it and/or
13; modify it under the terms of the GNU General Public License
14; as published by the Free Software Foundation, in version 3 of the
15; License.
16;
17; This program is distributed in the hope that it will be useful, but
18; WITHOUT ANY WARRANTY; without even the implied warranty of
19; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20; General Public License for more details.
21;
22; You should have received a copy of the GNU General Public License
23; along with this program; if not, see <https://www.gnu.org/licenses>.
24;
25; The contents of this file may alternatively be used under the terms
26; of the Common Development and Distribution License Version 1.0
27; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28; in the VirtualBox distribution, in which case the provisions of the
29; CDDL are applicable instead of those of the GPL.
30;
31; You may elect to license modified versions of this file under the
32; terms and conditions of either the GPL or the CDDL or both.
33;
34; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35;
36
37%include "bs3kit-template-header.mac"
38
39
40BS3_EXTERN_CMN Bs3KbdWait
41BS3_EXTERN_CMN Bs3KbdRead
42BS3_EXTERN_CMN Bs3KbdWrite
43
44
45;;
46; Enables the A20 gate.
47;
48; @uses Nothing.
49;
50BS3_PROC_BEGIN_CMN Bs3A20Enable, BS3_PBC_HYBRID_0_ARGS
51 push xBP
52 mov xBP, xSP
53BONLY64 sub rsp, 20h
54
55 call BS3_CMN_NM(Bs3A20EnableViaPortA)
56;; @todo real 286 support
57; call BS3_CMN_NM(Bs3A20EnableViaKbd)
58
59 pop xBP
60 BS3_HYBRID_RET
61BS3_PROC_END_CMN Bs3A20Enable
62
63
64;;
65; Enables the A20 gate via the keyboard controller.
66;
67; @uses Nothing.
68;
69BS3_PROC_BEGIN_CMN Bs3A20EnableViaKbd, BS3_PBC_HYBRID_0_ARGS
70 push xBP
71 mov xBP, xSP
72 push xAX
73 pushf
74 cli
75BONLY64 sub rsp, 20h
76
77 call Bs3KbdWait
78 push 0d0h ; KBD_CCMD_READ_OUTPORT
79 call Bs3KbdRead
80
81 or al, 002h
82 push xAX
83 push 0d1h ; KBD_CCMD_WRITE_OUTPORT
84 call Bs3KbdWrite
85
86 add xSP, xCB*3 ; both the above calls
87
88 mov al, 0ffh ; KBD_CMD_RESET
89 out 64h, al
90 call Bs3KbdWait
91
92BONLY64 add rsp, 20h
93 popf
94 pop xAX
95 pop xBP
96 BS3_HYBRID_RET
97BS3_PROC_END_CMN Bs3A20EnableViaKbd
98
99
100;;
101; Enables the A20 gate via control port A (PS/2 style).
102;
103; @uses Nothing.
104;
105BS3_PROC_BEGIN_CMN Bs3A20EnableViaPortA, BS3_PBC_HYBRID_0_ARGS
106 push xBP
107 mov xBP, xSP
108 push xAX
109
110 ; Use Control port A, assuming a PS/2 style system.
111 in al, 092h
112 test al, 02h
113 jnz .done ; avoid trouble writing back the same value.
114 or al, 2 ; enable the A20 gate.
115 out 092h, al
116
117.done:
118 pop xAX
119 pop xBP
120 BS3_HYBRID_RET
121BS3_PROC_END_CMN Bs3A20EnableViaPortA
122
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