/* $NetBSD: biosmemx.S,v 1.13 2024/08/24 20:23:11 riastradh Exp $ */
/*
* Copyright (c) 1997, 1999
* Matthias Drochner. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <machine/asm.h>
.text
/*
* int getextmem2(int buffer[2])
*
* return: 0=OK, -1=error
* buffer[0]: extmem kBytes below 16M (max 15M/1024)
* buffer[1]: extmem above 16M, in 64k units
*/
ENTRY(getextmem2)
pushl %ebp
movl %esp,%ebp
pushl %ebx
pushl %ecx
pushl %edx
push %esi
push %edi
call _C_LABEL(prot_to_real)
.code16
xorl %ebx,%ebx
movl $0xe801,%eax
int $0x15
pushf
movw %si,%ax
orw %si,%bx
jz 1f /* if zero use configured values */
movw %cx,%ax /* k below 16M (max 0x3c00 = 15MB) */
movw %dx,%bx /* 64k above 16M */
1:
popf
setc %bl
calll _C_LABEL(real_to_prot)
.code32
movl 8(%ebp),%edi
xorl %eax,%eax
movw %cx,%ax
stosl
movw %dx,%ax
stosl
movb %bl,%al
cbw
pop %edi
pop %esi
popl %edx
popl %ecx
popl %ebx
popl %ebp
ret
/*
* int getmementry(int *iterator, int buffer[6])
*
* return: 0=ok, else error
* buffer[0]: start of memory chunk
* buffer[2]: length (bytes)
* buffer[4]: type
* buffer[5]: ACPI 3.0 Extended Attributes bitfield (unused)
*
* Some buggy BIOSes may write to 24 bytes even if only 20 were requested.
* Therefore, the buffer is defined for 6 elements to avoid stack buffer
* overruns. See PR install/49470.
*
* More details can be found in the:
*
* Advanced Configuration and Power Interface (ACPI)
* Specification, Release 6.5, 2022-08-29, UEFI Forum, Inc.,
* Sec. 15.1 `INT 15H E820H - Query System Address Map',
* pp. 756-757
*
https://uefi.org/sites/default/files/resources/ACPI_Spec_6_5_Aug29.pdf#page=824
*
https://uefi.org/specs/ACPI/6.5/15_System_Address_Map_Interfaces.html#int-15h-e820h-query-system-address-map
*
* as well as this OSDev.org wiki page:
*
*
https://wiki.osdev.org/Detecting_Memory_(x86)#BIOS_Function:_INT_0x15,_EAX_=_0xE820
*/
ENTRY(getmementry)
pushl %ebp
movl %esp,%ebp
pushl %ebx
pushl %ecx
pushl %edx
push %esi
push %edi
movl 8(%ebp),%eax
movl 0(%eax),%ebx /* index */
movl $20,%ecx /* Buffer size */
movl $0x534d4150,%edx /* "SMAP" */
movl 12(%ebp),%edi /* buffer address */
call _C_LABEL(prot_to_real)
.code16
push %di
shrl $4,%edi
mov %ds,%ax
add %di,%ax
mov %ax,%es
pop %di
and $0xf,%di /* buffer address now in ES:DI */
movl $0xe820,%eax /* Some BIOS check EAX value */
int $0x15
setc %cl
calll _C_LABEL(real_to_prot)
.code32
movl 8(%ebp),%eax
movl %ebx,0(%eax) /* updated index */
xorl %eax,%eax
movb %cl,%al
pop %edi
pop %esi
popl %edx
popl %ecx
popl %ebx
popl %ebp
ret
/*
* int biosA20(void)
*
* return: 0=ok, else error
*/
ENTRY(biosA20)
pushl %ebp
movl %esp,%ebp
pushl %ebx
pushl %ecx
pushl %edx
push %esi
push %edi
call _C_LABEL(prot_to_real)
.code16
movl $0x2401,%eax
int $0x15
setc %cl
calll _C_LABEL(real_to_prot)
.code32
movzbl %cl,%eax
pop %edi
pop %esi
popl %edx
popl %ecx
popl %ebx
popl %ebp
ret
