| 1 | ; $Id: bs3-cmn-A20Disable.asm 106061 2024-09-16 14:03:52Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - Bs3A20Disable.
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| 4 | ;
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| 5 |
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| 6 | ;
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| 7 | ; Copyright (C) 2007-2024 Oracle and/or its affiliates.
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| 8 | ;
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| 9 | ; This file is part of VirtualBox base platform packages, as
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| 10 | ; available from https://www.virtualbox.org.
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| 11 | ;
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| 12 | ; This program is free software; you can redistribute it and/or
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| 13 | ; modify it under the terms of the GNU General Public License
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| 14 | ; as published by the Free Software Foundation, in version 3 of the
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| 15 | ; License.
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| 16 | ;
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| 17 | ; This program is distributed in the hope that it will be useful, but
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| 18 | ; WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | ; General Public License for more details.
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| 21 | ;
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| 22 | ; You should have received a copy of the GNU General Public License
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| 23 | ; along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | ;
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| 25 | ; The contents of this file may alternatively be used under the terms
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| 26 | ; of the Common Development and Distribution License Version 1.0
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| 27 | ; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | ; in the VirtualBox distribution, in which case the provisions of the
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| 29 | ; CDDL are applicable instead of those of the GPL.
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| 30 | ;
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| 31 | ; You may elect to license modified versions of this file under the
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| 32 | ; terms and conditions of either the GPL or the CDDL or both.
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| 33 | ;
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| 34 | ; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | ;
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| 36 |
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| 37 | %include "bs3kit-template-header.mac"
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| 38 |
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| 39 |
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| 40 | BS3_EXTERN_CMN Bs3KbdWait
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| 41 | BS3_EXTERN_CMN Bs3KbdRead
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| 42 | BS3_EXTERN_CMN Bs3KbdWrite
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| 43 |
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| 44 |
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| 45 | ;;
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| 46 | ; Disables the A20 gate.
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| 47 | ;
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| 48 | ; @uses Nothing.
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| 49 | ;
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| 50 | BS3_PROC_BEGIN_CMN Bs3A20Disable, BS3_PBC_HYBRID_0_ARGS
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| 51 | ; Must call both because they may be ORed together on real HW.
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| 52 | BONLY64 sub rsp, 20h
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| 53 | call BS3_CMN_NM(Bs3A20DisableViaKbd)
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| 54 | call BS3_CMN_NM(Bs3A20DisableViaPortA)
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| 55 | BONLY64 add rsp, 20h
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| 56 | BS3_HYBRID_RET
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| 57 | BS3_PROC_END_CMN Bs3A20Disable
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| 58 |
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| 59 |
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| 60 | ;;
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| 61 | ; Disables the A20 gate via control port A (PS/2 style).
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| 62 | ;
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| 63 | ; @uses Nothing.
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| 64 | ;
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| 65 | BS3_PROC_BEGIN_CMN Bs3A20DisableViaPortA, BS3_PBC_HYBRID_0_ARGS
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| 66 | push xAX
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| 67 |
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| 68 | ; Use Control port A, assuming a PS/2 style system.
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| 69 | in al, 092h
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| 70 | test al, 02h
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| 71 | jz .done ; avoid trouble writing back the same value.
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| 72 | and al, 0fdh ; disable the A20 gate.
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| 73 | out 092h, al
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| 74 |
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| 75 | .done:
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| 76 | pop xAX
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| 77 | BS3_HYBRID_RET
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| 78 | BS3_PROC_END_CMN Bs3A20DisableViaPortA
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| 79 |
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| 80 |
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| 81 | ;;
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| 82 | ; Disables the A20 gate via the keyboard controller.
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| 83 | ;
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| 84 | ; @uses Nothing.
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| 85 | ;
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| 86 | BS3_PROC_BEGIN_CMN Bs3A20DisableViaKbd, BS3_PBC_HYBRID_0_ARGS
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| 87 | push xBP
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| 88 | mov xBP, xSP
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| 89 | push xAX
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| 90 | pushf
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| 91 | cli
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| 92 | BONLY64 sub rsp, 20h
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| 93 |
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| 94 | call Bs3KbdWait
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| 95 | push 0d0h ; KBD_CCMD_READ_OUTPORT
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| 96 | call Bs3KbdRead
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| 97 |
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| 98 | and al, 0fdh ; ~2
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| 99 | push xAX
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| 100 | push 0d1h ; KBD_CCMD_WRITE_OUTPORT
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| 101 | call Bs3KbdWrite
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| 102 |
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| 103 | add xSP, xCB*3 ; Clean up both the above calls.
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| 104 |
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| 105 | mov al, 0ffh ; KBD_CMD_RESET
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| 106 | out 64h, al
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| 107 | call Bs3KbdWait
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| 108 |
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| 109 | BONLY64 add rsp, 20h
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| 110 | popf
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| 111 | pop xAX
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| 112 | pop xBP
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| 113 | BS3_HYBRID_RET
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| 114 | BS3_PROC_END_CMN Bs3A20DisableViaKbd
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| 115 |
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