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106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
/*
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* Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/**
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* @file
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*
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* Memory map
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*
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*/
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#include <stddef.h>
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#include <stdio.h>
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#include <string.h>
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#include "wimboot.h"
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#include "memmap.h"
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/** Buffer for INT 15,e820 calls */
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static struct e820_entry e820_buf __attribute__ (( section ( ".bss16" ) ));
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/** Continuation value for next INT 15,e820 call */
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static uint32_t e820_ebx;
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/**
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* Get system memory map entry
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*
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* @v prev Previous system memory map entry, or NULL at start
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* @v next Next system memory map entry, or NULL at end
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*/
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struct e820_entry * memmap_next ( struct e820_entry *prev ) {
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struct bootapp_callback_params params;
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/* Reset buffer and continuation value if restarting */
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if ( ! prev ) {
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memset ( &e820_buf, 0, sizeof ( e820_buf ) );
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e820_ebx = 0;
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} else if ( e820_ebx == 0 ) {
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/* Reach the end */
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return NULL;
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}
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/* Read system memory map */
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memset ( ¶ms, 0, sizeof ( params ) );
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do {
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/* Call INT 15,e820 */
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params.vector.interrupt = 0x15;
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params.eax = 0xe820;
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params.ebx = e820_ebx;
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params.ecx = sizeof ( e820_buf );
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params.edx = E820_SMAP;
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params.es = BASE_SEG;
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params.edi = ( ( ( void * ) &e820_buf ) -
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( ( void * ) BASE_ADDRESS ) );
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call_interrupt ( ¶ms );
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/* Record continuation value */
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e820_ebx = params.ebx;
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/* Check result */
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if ( params.eflags & CF ) {
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DBG ( "INT 15,e820 failed: error %02x\n", params.ah );
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break;
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}
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if ( params.eax != E820_SMAP ) {
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DBG ( "INT 15,e820 invalid SMAP signature %08x\n",
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params.eax );
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break;
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}
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DBG2 ( "INT 15,e820 region [%llx,%llx) type %d\n",
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e820_buf.start, ( e820_buf.start + e820_buf.len ),
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e820_buf.type );
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/* Skip non-RAM regions */
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if ( e820_buf.type != E820_TYPE_RAM )
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continue;
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if ( params.ecx > offsetof ( typeof ( e820_buf ), attrs ) ) {
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if ( ! ( e820_buf.attrs & E820_ATTR_ENABLED ) )
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continue;
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if ( e820_buf.attrs & E820_ATTR_NONVOLATILE )
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continue;
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}
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/* Return this region */
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return &e820_buf;
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} while ( e820_ebx != 0 );
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return NULL;
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}
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