| 1 | ; $Id: bs3-cmn-A20Disable.asm 76553 2019-01-01 01:45:53Z 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) 2007-2019 Oracle Corporation
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| 8 | ;
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| 9 | ; This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | ; available from http://www.virtualbox.org. This file is free software;
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| 11 | ; you can redistribute it and/or modify it under the terms of the GNU
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| 12 | ; General Public License (GPL) as published by the Free Software
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| 13 | ; Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | ; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | ; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | ;
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| 17 | ; The contents of this file may alternatively be used under the terms
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| 18 | ; of the Common Development and Distribution License Version 1.0
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| 19 | ; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | ; VirtualBox OSE distribution, in which case the provisions of the
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| 21 | ; CDDL are applicable instead of those of the GPL.
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| 22 | ;
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| 23 | ; You may elect to license modified versions of this file under the
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| 24 | ; terms and conditions of either the GPL or the CDDL or both.
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| 25 | ;
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| 26 |
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| 27 | %include "bs3kit-template-header.mac"
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| 28 |
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| 29 |
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| 30 | BS3_EXTERN_CMN Bs3KbdWait
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| 31 | BS3_EXTERN_CMN Bs3KbdRead
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| 32 | BS3_EXTERN_CMN Bs3KbdWrite
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| 33 |
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| 34 |
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| 35 | ;;
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| 36 | ; Disables the A20 gate.
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| 37 | ;
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| 38 | ; @uses Nothing.
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| 39 | ;
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| 40 | BS3_PROC_BEGIN_CMN Bs3A20Disable, BS3_PBC_HYBRID_0_ARGS
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| 41 | ; Must call both because they may be ORed together on real HW.
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| 42 | BONLY64 sub rsp, 20h
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| 43 | call BS3_CMN_NM(Bs3A20DisableViaKbd)
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| 44 | call BS3_CMN_NM(Bs3A20DisableViaPortA)
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| 45 | BONLY64 add rsp, 20h
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| 46 | BS3_HYBRID_RET
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| 47 | BS3_PROC_END_CMN Bs3A20Disable
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| 48 |
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| 49 |
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| 50 | ;;
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| 51 | ; Disables the A20 gate via control port A (PS/2 style).
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| 52 | ;
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| 53 | ; @uses Nothing.
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| 54 | ;
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| 55 | BS3_PROC_BEGIN_CMN Bs3A20DisableViaPortA, BS3_PBC_HYBRID_0_ARGS
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| 56 | push xAX
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| 57 |
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| 58 | ; Use Control port A, assuming a PS/2 style system.
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| 59 | in al, 092h
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| 60 | test al, 02h
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| 61 | jz .done ; avoid trouble writing back the same value.
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| 62 | and al, 0fdh ; disable the A20 gate.
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| 63 | out 092h, al
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| 64 |
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| 65 | .done:
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| 66 | pop xAX
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| 67 | BS3_HYBRID_RET
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| 68 | BS3_PROC_END_CMN Bs3A20DisableViaPortA
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| 69 |
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| 70 |
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| 71 | ;;
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| 72 | ; Disables the A20 gate via the keyboard controller.
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| 73 | ;
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| 74 | ; @uses Nothing.
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| 75 | ;
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| 76 | BS3_PROC_BEGIN_CMN Bs3A20DisableViaKbd, BS3_PBC_HYBRID_0_ARGS
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| 77 | push xBP
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| 78 | mov xBP, xSP
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| 79 | push xAX
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| 80 | pushf
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| 81 | cli
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| 82 | BONLY64 sub rsp, 20h
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| 83 |
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| 84 | call Bs3KbdWait
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| 85 | push 0d0h ; KBD_CCMD_READ_OUTPORT
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| 86 | call Bs3KbdRead
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| 87 |
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| 88 | and al, 0fdh ; ~2
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| 89 | push xAX
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| 90 | push 0d1h ; KBD_CCMD_WRITE_OUTPORT
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| 91 | call Bs3KbdWrite
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| 92 |
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| 93 | add xSP, xCB*3 ; Clean up both the above calls.
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| 94 |
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| 95 | mov al, 0ffh ; KBD_CMD_RESET
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| 96 | out 64h, al
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| 97 | call Bs3KbdWait
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| 98 |
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| 99 | BONLY64 add rsp, 20h
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| 100 | popf
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| 101 | pop xAX
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| 102 | pop xBP
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| 103 | BS3_HYBRID_RET
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| 104 | BS3_PROC_END_CMN Bs3A20DisableViaKbd
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| 105 |
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