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|
; $Id: bs3-cmn-A20Enable.asm $
;; @file
; BS3Kit - Bs3A20Enable.
;
;
; Copyright (C) 2007-2019 Oracle Corporation
;
; This file is part of VirtualBox Open Source Edition (OSE), as
; available from http://www.virtualbox.org. This file is free software;
; you can redistribute it and/or modify it under the terms of the GNU
; General Public License (GPL) as published by the Free Software
; Foundation, in version 2 as it comes in the "COPYING" file of the
; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
; VirtualBox OSE 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.
;
%include "bs3kit-template-header.mac"
BS3_EXTERN_CMN Bs3KbdWait
BS3_EXTERN_CMN Bs3KbdRead
BS3_EXTERN_CMN Bs3KbdWrite
;;
; Enables the A20 gate.
;
; @uses Nothing.
;
BS3_PROC_BEGIN_CMN Bs3A20Enable, BS3_PBC_HYBRID_0_ARGS
push xBP
mov xBP, xSP
BONLY64 sub rsp, 20h
call BS3_CMN_NM(Bs3A20EnableViaPortA)
;; @todo real 286 support
; call BS3_CMN_NM(Bs3A20EnableViaKbd)
pop xBP
BS3_HYBRID_RET
BS3_PROC_END_CMN Bs3A20Enable
;;
; Enables the A20 gate via the keyboard controller.
;
; @uses Nothing.
;
BS3_PROC_BEGIN_CMN Bs3A20EnableViaKbd, BS3_PBC_HYBRID_0_ARGS
push xBP
mov xBP, xSP
push xAX
pushf
cli
BONLY64 sub rsp, 20h
call Bs3KbdWait
push 0d0h ; KBD_CCMD_READ_OUTPORT
call Bs3KbdRead
or al, 002h
push xAX
push 0d1h ; KBD_CCMD_WRITE_OUTPORT
call Bs3KbdWrite
add xSP, xCB*3 ; both the above calls
mov al, 0ffh ; KBD_CMD_RESET
out 64h, al
call Bs3KbdWait
BONLY64 add rsp, 20h
popf
pop xAX
pop xBP
BS3_HYBRID_RET
BS3_PROC_END_CMN Bs3A20EnableViaKbd
;;
; Enables the A20 gate via control port A (PS/2 style).
;
; @uses Nothing.
;
BS3_PROC_BEGIN_CMN Bs3A20EnableViaPortA, BS3_PBC_HYBRID_0_ARGS
push xBP
mov xBP, xSP
push xAX
; Use Control port A, assuming a PS/2 style system.
in al, 092h
test al, 02h
jnz .done ; avoid trouble writing back the same value.
or al, 2 ; enable the A20 gate.
out 092h, al
.done:
pop xAX
pop xBP
BS3_HYBRID_RET
BS3_PROC_END_CMN Bs3A20EnableViaPortA
|
