82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
/*
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* Copyright (C) 2012 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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FILE_LICENCE ( GPL2_OR_LATER );
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/** @file
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*
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* Largest memory block
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*
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*/
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#include <stdint.h>
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#include <ipxe/uaccess.h>
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#include <ipxe/io.h>
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#include <ipxe/memblock.h>
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/**
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* Find largest usable memory region
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*
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* @ret start Start of region
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* @ret len Length of region
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*/
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size_t largest_memblock ( userptr_t *start ) {
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struct memory_map memmap;
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struct memory_region *region;
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physaddr_t max = ~( ( physaddr_t ) 0 );
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physaddr_t region_start;
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physaddr_t region_end;
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size_t region_len;
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unsigned int i;
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size_t len = 0;
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/* Avoid returning uninitialised data on error */
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*start = UNULL;
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/* Scan through all memory regions */
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get_memmap ( &memmap );
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for ( i = 0 ; i < memmap.count ; i++ ) {
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region = &memmap.regions[i];
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DBG ( "Considering [%llx,%llx)\n", region->start, region->end );
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/* Truncate block to maximum physical address */
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if ( region->start > max ) {
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DBG ( "...starts after maximum address %lx\n", max );
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continue;
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}
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region_start = region->start;
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if ( region->end > max ) {
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DBG ( "...end truncated to maximum address %lx\n", max);
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region_end = 0; /* =max, given the wraparound */
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} else {
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region_end = region->end;
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}
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region_len = ( region_end - region_start );
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/* Use largest block */
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if ( region_len > len ) {
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DBG ( "...new best block found\n" );
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*start = phys_to_user ( region_start );
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len = region_len;
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}
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}
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return len;
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}
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