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/*
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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; either version 2 of the
* License, or any later version.
*
* 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stdint.h>
#include <errno.h>
#include <realmode.h>
#include <bios.h>
#include <memmap.h>
/**
* @file
*
* Memory mapping
*
*/
/** Magic value for INT 15,e820 calls */
#define SMAP ( 0x534d4150 )
/** An INT 15,e820 memory map entry */
struct e820_entry {
/** Start of region */
uint64_t start;
/** Length of region */
uint64_t len;
/** Type of region */
uint32_t type;
} __attribute__ (( packed ));
#define E820_TYPE_RAM 1 /**< Normal memory */
#define E820_TYPE_RESERVED 2 /**< Reserved and unavailable */
#define E820_TYPE_ACPI 3 /**< ACPI reclaim memory */
#define E820_TYPE_NVS 4 /**< ACPI NVS memory */
/** Buffer for INT 15,e820 calls */
static struct e820_entry __data16 ( e820buf );
#define e820buf __use_data16 ( e820buf )
/**
* Get size of base memory from BIOS free base memory counter
*
* @ret basemem Base memory size, in kB
*/
static unsigned int basememsize ( void ) {
uint16_t basemem;
get_real ( basemem, BDA_SEG, 0x0013 );
DBG ( "Base memory size %dkB\n", basemem );
return basemem;
}
/**
* Get size of extended memory via INT 15,e801
*
* @ret extmem Extended memory size, in kB, or 0
*/
static unsigned int extmemsize_e801 ( void ) {
uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
unsigned int flags;
unsigned int extmem;
__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
"int $0x15\n\t"
"pushfw\n\t"
"popw %w0\n\t" )
: "=r" ( flags ),
"=a" ( extmem_1m_to_16m_k ),
"=b" ( extmem_16m_plus_64k ),
"=c" ( confmem_1m_to_16m_k ),
"=d" ( confmem_16m_plus_64k )
: "a" ( 0xe801 ) );
if ( flags & CF )
return 0;
if ( ! ( extmem_1m_to_16m_k | extmem_16m_plus_64k ) ) {
extmem_1m_to_16m_k = confmem_1m_to_16m_k;
extmem_16m_plus_64k = confmem_16m_plus_64k;
}
extmem = ( extmem_1m_to_16m_k + ( extmem_16m_plus_64k * 64 ) );
DBG ( "Extended memory size %d+64*%d=%d kB\n",
extmem_1m_to_16m_k, extmem_16m_plus_64k, extmem );
return extmem;
}
/**
* Get size of extended memory via INT 15,88
*
* @ret extmem Extended memory size, in kB
*/
static unsigned int extmemsize_88 ( void ) {
uint16_t extmem;
/* Ignore CF; it is not reliable for this call */
__asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
: "=a" ( extmem ) : "a" ( 0x8800 ) );
DBG ( "Extended memory size %d kB\n", extmem );
return extmem;
}
/**
* Get size of extended memory
*
* @ret extmem Extended memory size, in kB
*/
static unsigned int extmemsize ( void ) {
unsigned int extmem;
/* Try INT 15,e801 first, then fall back to INT 15,88 */
extmem = extmemsize_e801();
if ( ! extmem )
extmem = extmemsize_88();
return extmem;
}
/**
* Get e820 memory map
*
* @v memmap Memory map to fill in
* @ret rc Return status code
*/
static int meme820 ( struct memory_map *memmap ) {
struct memory_region *region = memmap->regions;
uint32_t next = 0;
uint32_t smap;
unsigned int flags;
unsigned int discard_c, discard_d, discard_D;
do {
__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
"int $0x15\n\t"
"pushfw\n\t"
"popw %w0\n\t" )
: "=r" ( flags ), "=a" ( smap ),
"=b" ( next ), "=D" ( discard_D ),
"=c" ( discard_c ), "=d" ( discard_d )
: "a" ( 0xe820 ), "b" ( next ),
"D" ( &__from_data16 ( e820buf ) ),
"c" ( sizeof ( e820buf ) ),
"d" ( SMAP )
: "memory" );
if ( smap != SMAP )
return -ENOTSUP;
if ( flags & CF )
break;
DBG ( "E820 region [%llx,%llx) type %d\n", e820buf.start,
( e820buf.start + e820buf.len ), ( int ) e820buf.type );
if ( e820buf.type != E820_TYPE_RAM )
continue;
region->start = e820buf.start;
region->end = e820buf.start + e820buf.len;
region++;
memmap->count++;
} while ( ( next != 0 ) &&
( memmap->count < ( sizeof ( memmap->regions ) /
sizeof ( memmap->regions[0] ) ) ) );
return 0;
}
/**
* Get memory map
*
* @v memmap Memory map to fill in
*/
void get_memmap ( struct memory_map *memmap ) {
unsigned int basemem, extmem;
int rc;
/* Clear memory map */
memset ( memmap, 0, sizeof ( *memmap ) );
/* Get base and extended memory sizes */
basemem = basememsize();
extmem = extmemsize();
/* Try INT 15,e820 first */
if ( ( rc = meme820 ( memmap ) ) == 0 )
return;
/* Fall back to constructing a map from basemem and extmem sizes */
memmap->regions[0].end = ( basemem * 1024 );
memmap->regions[1].start = 0x100000;
memmap->regions[1].end = 0x100000 + ( extmem * 1024 );
memmap->count = 2;
}
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