diff options
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Disable.asm')
| -rw-r--r-- | src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Disable.asm | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Disable.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Disable.asm new file mode 100644 index 00000000..0aa3d1ba --- /dev/null +++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Disable.asm @@ -0,0 +1,105 @@ +; $Id: bs3-cmn-A20Disable.asm $ +;; @file +; BS3Kit - Bs3A20Disable. +; + +; +; 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 + + +;; +; Disables the A20 gate. +; +; @uses Nothing. +; +BS3_PROC_BEGIN_CMN Bs3A20Disable, BS3_PBC_HYBRID_0_ARGS + ; Must call both because they may be ORed together on real HW. +BONLY64 sub rsp, 20h + call BS3_CMN_NM(Bs3A20DisableViaKbd) + call BS3_CMN_NM(Bs3A20DisableViaPortA) +BONLY64 add rsp, 20h + BS3_HYBRID_RET +BS3_PROC_END_CMN Bs3A20Disable + + +;; +; Disables the A20 gate via control port A (PS/2 style). +; +; @uses Nothing. +; +BS3_PROC_BEGIN_CMN Bs3A20DisableViaPortA, BS3_PBC_HYBRID_0_ARGS + push xAX + + ; Use Control port A, assuming a PS/2 style system. + in al, 092h + test al, 02h + jz .done ; avoid trouble writing back the same value. + and al, 0fdh ; disable the A20 gate. + out 092h, al + +.done: + pop xAX + BS3_HYBRID_RET +BS3_PROC_END_CMN Bs3A20DisableViaPortA + + +;; +; Disables the A20 gate via the keyboard controller. +; +; @uses Nothing. +; +BS3_PROC_BEGIN_CMN Bs3A20DisableViaKbd, 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 + + and al, 0fdh ; ~2 + push xAX + push 0d1h ; KBD_CCMD_WRITE_OUTPORT + call Bs3KbdWrite + + add xSP, xCB*3 ; Clean up 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 Bs3A20DisableViaKbd + |