; $Id: bootsector2-cpu-a20-1.asm $ ;; @file ; Bootsector that checks the A20 emulation. ; ; ; 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 . ; ; 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 "iprt/asmdefs.mac" %include "iprt/x86.mac" %include "VBox/VMMDevTesting.mac" ; ; Include and execute the init code. ; %define BS2_WITH_TRAPS %define BS2_INIT_RM %define BS2_INC_PE16 %define BS2_INC_PE32 %define BS2_INC_PP32 %define BS2_INC_PAE32 %define BS2_INC_LM64 %include "bootsector2-common-init-code.mac" ; ; The benchmark driver ; BEGINPROC main ; ; Test prologue. ; mov ax, .s_szTstName call TestInit_r86 ; ; The actual tests. ; call TestA20_1 ; must come first call TestA20_rm_rm ;call TestA20_rm_pe16 call TestA20_rm_pe32 call TestA20_rm_pp32 ;call TestA20_rm_pp16 call TestA20_rm_pae32 call TestA20_rm_lm64 ; ; We're done. ; call TestTerm_r86 call Bs2Panic .s_szTstName: db 'tstA20-1', 0 .s_szInitialA20Status: db 'Initial A20 state', 0 ENDPROC main ; ; Do some initial tests. ; BEGINPROC TestA20_1 push eax push edx push ecx push ebx push edi ; ; Check that the A20 gate is disabled when we come from the BIOS. ; mov ax, .s_szInitialA20Status call TestSub_r86 call IsA20GateEnabled_rm mov di, ax ; save A20 state in AX for bios test. cmp al, 0 je .initial_state_done mov ax, .s_szBadInitialA20Status call TestFailed_r86 jmp .initial_state_done .s_szInitialA20Status: db 'Initial A20 state', 0 .s_szBadInitialA20Status: db 'Initial A20 state is enabled, expected disabled', 10, 13, 0 .initial_state_done: call TestSubDone_r86 ; ; Disable it via the BIOS interface and check. ; mov ax, .s_szBios call TestSub_r86 ; query support mov ax, 2403h int 15h jnc .bios_2403_ok movzx edx, ax mov ax, .s_szBios2403Error mov cl, VMMDEV_TESTING_UNIT_NONE call TestValueU32_r86 jmp .bios_2403_done .bios_2403_ok: movzx edx, al mov ax, .s_szBios2403Mask mov cl, VMMDEV_TESTING_UNIT_NONE call TestValueU32_r86 .bios_2403_done: ; Check what the bios thinks the state is. call BiosIsA20GateEnabled_rm cmp ax, di je .bios_2402_done push di push ax push word ds push word .s_szBios2402Error call TestFailedF_r86 add sp, 8 .bios_2402_done: ; Loop to make sure we get all transitions and ends up with A20 disabled. mov cx, 10h .bios_loop: ; enable it mov ax, 2401h push cx ; paranoia that seems necessary for at least one AMI bios. int 15h pop cx jnc .bios_continue1 mov ax, .s_szBiosFailed2401 jmp .bios_failed .bios_continue1: call IsA20GateEnabled_rm cmp al, 1 je .bios_continue2 mov ax, .s_szBiosEnableFailed jmp .bios_failed .bios_continue2: ; disable mov ax, 2400h push cx ; paranoia that seems necessary for at least one AMI bios. int 15h pop cx jnc .bios_continue3 mov ax, .s_szBiosFailed2400 jmp .bios_failed .bios_continue3: call IsA20GateEnabled_rm cmp al, 0 je .bios_continue4 mov ax, .s_szBiosDisableFailed jmp .bios_failed .bios_continue4: loop .bios_loop jmp .bios_done .s_szBios: db 'INT 15h AH=24 A20 Gate interface', 0 .s_szBios2403Mask: db 'AX=2403 return (AL)', 0 .s_szBios2403Error: db 'AX=2403 error (AX)', 10, 13, 0 .s_szBios2402Error: db '2402h -> AX=%RX16 expected %RX16', 10, 13, 0 .s_szBiosFailed2400: db '2400h interface failed', 10, 13, 0 .s_szBiosFailed2401: db '2401h interface failed', 10, 13, 0 .s_szBiosDisableFailed: db 'BIOS failed to disable A20 (or bad CPU)', 10, 13, 0 .s_szBiosEnableFailed: db 'BIOS failed to enable A20', 10, 13, 0 .bios_failed: call TestFailed_r86 .bios_done: call TestSubDone_r86 call Bs2DisableA20ViaPortA_r86 call Bs2DisableA20ViaKbd_r86 ; ; Test the fast A20 gate interface. ; mov ax, .s_szFastA20 call TestSub_r86 mov cx, 10h .fast_loop: call Bs2EnableA20ViaPortA_r86 call IsA20GateEnabled_rm cmp al, 1 mov ax, .s_szFastEnableFailed jne .fast_failed call Bs2DisableA20ViaPortA_r86 call IsA20GateEnabled_rm cmp al, 0 mov ax, .s_szFastDisableFailed jne .fast_failed loop .fast_loop jmp .fast_done .s_szFastA20: db 'Fast A20 Gate Interface', 0 .s_szFastDisableFailed: db 'Fast A20 gate disabling failed', 10, 13, 0 .s_szFastEnableFailed: db 'Fast A20 gate enabling failed', 10, 13, 0 .fast_failed: call TestFailed_r86 .fast_done: call TestSubDone_r86 call Bs2DisableA20ViaPortA_r86 call Bs2DisableA20ViaKbd_r86 ; ; Test the keyboard interface. ; mov ax, .s_szKeyboardA20 call TestSub_r86 mov cx, 10h .kbd_loop: call Bs2EnableA20ViaKbd_r86 call IsA20GateEnabled_rm cmp al, 1 mov ax, .s_szKbdEnableFailed jne .kbd_failed call Bs2DisableA20ViaKbd_r86 call IsA20GateEnabled_rm cmp al, 0 mov ax, .s_szKbdDisableFailed jne .kbd_failed loop .kbd_loop jmp .kbd_done .s_szKeyboardA20: db 'Keyboard A20 Gate Interface', 0 .s_szKbdDisableFailed: db 'Disabling the A20 gate via the keyboard controller failed', 10, 13, 0 .s_szKbdEnableFailed: db 'Enabling the A20 gate via the keyboard controller failed', 10, 13, 0 .kbd_failed: call TestFailed_r86 .kbd_done: call TestSubDone_r86 call Bs2DisableA20ViaPortA_r86 call Bs2DisableA20ViaKbd_r86 pop edi pop ebx pop ecx pop edx pop eax ret ENDPROC TestA20_1 ;; ; Checks if the A20 gate is enabled. ; ; This is do by temporarily changing a word at address 0000000h and see if this ; is reflected at address 0100000h (1 MB). The word written is ; ~*(word *)0x100000h to make sure it won't accidentally match. ; ; @returns ax 1 if enabled, 0 if disabled. ; BEGINPROC IsA20GateEnabled_rm push ds push es push dx pushf cli .once_again: xor ax, ax mov ds, ax dec ax mov es, ax mov ax, [es:0010h] ; 0ffff:0010 => 0100000h (1 MB) mov dx, [ds:0000h] ; 00000:0000 => 0000000h - save it not ax mov [ds:0000h], ax ; 0000000h - write ~[0100000h] cmp [es:0010h], ax ; 0100000h - same as 0000000h if A20 is disabled. mov [ds:0000h], dx ; 0000000h - restore original value setne al movzx ax, al popf pop dx pop es pop ds ret ENDPROC IsA20GateEnabled_rm ;; ; Checks if the BIOS thinks the A20 gate is enabled. ; ; @returns ax 1 if enabled, 0 if disabled. ; BEGINPROC BiosIsA20GateEnabled_rm push ecx push eax mov ax, 2402h int 15h jnc .ok mov al, 080h .ok: mov cx, ax pop eax mov ax, cx pop ecx ret ENDPROC BiosIsA20GateEnabled_rm ; ; Instantiate the template code. ; %include "bootsector2-template-footer.mac" ; reset the initial environemnt. %define TMPL_RM %include "bootsector2-cpu-a20-1-template.mac" ;%define TMPL_CMN_V86 ;%include "bootsector2-cpu-a20-1-template.mac" %define TMPL_PE16 %include "bootsector2-cpu-a20-1-template.mac" %define TMPL_PE32 %include "bootsector2-cpu-a20-1-template.mac" ;%define TMPL_PP16 ;%include "bootsector2-cpu-a20-1-template.mac" %define TMPL_PP32 %include "bootsector2-cpu-a20-1-template.mac" ;%define TMPL_PAE16 ;%include "bootsector2-cpu-a20-1-template.mac" %define TMPL_PAE32 %include "bootsector2-cpu-a20-1-template.mac" ;%define TMPL_LM16 ;%include "bootsector2-cpu-a20-1-template.mac" ;%define TMPL_LM32 ;%include "bootsector2-cpu-a20-1-template.mac" %define TMPL_LM64 %include "bootsector2-cpu-a20-1-template.mac" ; ; End sections and image. ; %include "bootsector2-common-end.mac"