diff options
Diffstat (limited to 'src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm')
| -rw-r--r-- | src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm new file mode 100644 index 00000000..bd4406d1 --- /dev/null +++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-cmn-A20Enable.asm @@ -0,0 +1,122 @@ +; $Id: bs3-cmn-A20Enable.asm $ +;; @file +; BS3Kit - Bs3A20Enable. +; + +; +; Copyright (C) 2007-2023 Oracle and/or its affiliates. +; +; This file is part of VirtualBox base platform packages, as +; available from https://www.virtualbox.org. +; +; This program is free software; you can redistribute it and/or +; modify it under the terms of the GNU General Public License +; as published by the Free Software Foundation, in version 3 of the +; License. +; +; This program is distributed in the hope that it will be useful, but +; WITHOUT ANY WARRANTY; without even the implied warranty of +; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +; General Public License for more details. +; +; You should have received a copy of the GNU General Public License +; along with this program; if not, see <https://www.gnu.org/licenses>. +; +; The contents of this file may alternatively be used under the terms +; of the Common Development and Distribution License Version 1.0 +; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included +; in the VirtualBox 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. +; +; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 +; + +%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 + |