VirtualBox

source: vbox/trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm@ 82968

Last change on this file since 82968 was 82968, checked in by vboxsync, 5 years ago

Copyright year updates by scm.

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File size: 2.9 KB
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1; $Id: bs3-cmn-A20Enable.asm 82968 2020-02-04 10:35:17Z vboxsync $
2;; @file
3; BS3Kit - Bs3A20Enable.
4;
5
6;
7; Copyright (C) 2007-2020 Oracle Corporation
8;
9; This file is part of VirtualBox Open Source Edition (OSE), as
10; available from http://www.virtualbox.org. This file is free software;
11; you can redistribute it and/or modify it under the terms of the GNU
12; General Public License (GPL) as published by the Free Software
13; Foundation, in version 2 as it comes in the "COPYING" file of the
14; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16;
17; The contents of this file may alternatively be used under the terms
18; of the Common Development and Distribution License Version 1.0
19; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
20; VirtualBox OSE distribution, in which case the provisions of the
21; CDDL are applicable instead of those of the GPL.
22;
23; You may elect to license modified versions of this file under the
24; terms and conditions of either the GPL or the CDDL or both.
25;
26
27%include "bs3kit-template-header.mac"
28
29
30BS3_EXTERN_CMN Bs3KbdWait
31BS3_EXTERN_CMN Bs3KbdRead
32BS3_EXTERN_CMN Bs3KbdWrite
33
34
35;;
36; Enables the A20 gate.
37;
38; @uses Nothing.
39;
40BS3_PROC_BEGIN_CMN Bs3A20Enable, BS3_PBC_HYBRID_0_ARGS
41 push xBP
42 mov xBP, xSP
43BONLY64 sub rsp, 20h
44
45 call BS3_CMN_NM(Bs3A20EnableViaPortA)
46;; @todo real 286 support
47; call BS3_CMN_NM(Bs3A20EnableViaKbd)
48
49 pop xBP
50 BS3_HYBRID_RET
51BS3_PROC_END_CMN Bs3A20Enable
52
53
54;;
55; Enables the A20 gate via the keyboard controller.
56;
57; @uses Nothing.
58;
59BS3_PROC_BEGIN_CMN Bs3A20EnableViaKbd, BS3_PBC_HYBRID_0_ARGS
60 push xBP
61 mov xBP, xSP
62 push xAX
63 pushf
64 cli
65BONLY64 sub rsp, 20h
66
67 call Bs3KbdWait
68 push 0d0h ; KBD_CCMD_READ_OUTPORT
69 call Bs3KbdRead
70
71 or al, 002h
72 push xAX
73 push 0d1h ; KBD_CCMD_WRITE_OUTPORT
74 call Bs3KbdWrite
75
76 add xSP, xCB*3 ; both the above calls
77
78 mov al, 0ffh ; KBD_CMD_RESET
79 out 64h, al
80 call Bs3KbdWait
81
82BONLY64 add rsp, 20h
83 popf
84 pop xAX
85 pop xBP
86 BS3_HYBRID_RET
87BS3_PROC_END_CMN Bs3A20EnableViaKbd
88
89
90;;
91; Enables the A20 gate via control port A (PS/2 style).
92;
93; @uses Nothing.
94;
95BS3_PROC_BEGIN_CMN Bs3A20EnableViaPortA, BS3_PBC_HYBRID_0_ARGS
96 push xBP
97 mov xBP, xSP
98 push xAX
99
100 ; Use Control port A, assuming a PS/2 style system.
101 in al, 092h
102 test al, 02h
103 jnz .done ; avoid trouble writing back the same value.
104 or al, 2 ; enable the A20 gate.
105 out 092h, al
106
107.done:
108 pop xAX
109 pop xBP
110 BS3_HYBRID_RET
111BS3_PROC_END_CMN Bs3A20EnableViaPortA
112
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