236 lines
6.8 KiB
C
236 lines
6.8 KiB
C
#include "stdint.h"
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#include "stddef.h"
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#include "realmode.h"
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#include "init.h"
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#include "etherboot.h"
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#include "memsizes.h"
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#define CF ( 1 << 0 )
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/* by Eric Biederman */
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struct meminfo meminfo;
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/**************************************************************************
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BASEMEMSIZE - Get size of the conventional (base) memory
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**************************************************************************/
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static unsigned short basememsize ( void ) {
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uint16_t int12_basememsize, fbms_basememsize;
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uint16_t basememsize;
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/* There are two methods for retrieving the base memory size:
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* INT 12 and the BIOS FBMS counter at 40:13. We read both
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* and use the smaller value, to be paranoid.
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*
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* We then store the smaller value in the BIOS FBMS counter so
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* that other code (e.g. basemem.c) can rely on it and not
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* have to use INT 12. This is especially important because
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* basemem.c functions can be called in a context in which
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* there is no real-mode stack (e.g. when trying to allocate
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* memory for a real-mode stack...)
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*/
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REAL_EXEC ( rm_basememsize,
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"int $0x12\n\t",
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1,
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OUT_CONSTRAINTS ( "=a" ( int12_basememsize ) ),
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IN_CONSTRAINTS (),
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CLOBBER ( "ebx", "ecx", "edx", "ebp", "esi", "edi" ) );
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get_real ( fbms_basememsize, 0x40, 0x13 );
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basememsize = ( int12_basememsize < fbms_basememsize ?
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int12_basememsize : fbms_basememsize );
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put_real ( basememsize, 0x40, 0x13 );
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return basememsize;
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}
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/**************************************************************************
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MEMSIZE - Determine size of extended memory, in kB
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**************************************************************************/
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static unsigned int memsize ( void ) {
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uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
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uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
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uint16_t flags;
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int memsize;
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/* Try INT 15,e801 first
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*
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* Some buggy BIOSes don't clear/set carry on pass/error of
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* e801h memory size call or merely pass cx,dx through without
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* changing them, so we set carry and zero cx,dx before call.
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*/
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REAL_EXEC ( rm_mem_e801,
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"stc\n\t"
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"int $0x15\n\t"
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"pushfw\n\t" /* flags -> %di */
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"popw %%di\n\t",
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5,
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OUT_CONSTRAINTS ( "=a" ( extmem_1m_to_16m_k ),
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"=b" ( extmem_16m_plus_64k ),
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"=c" ( confmem_1m_to_16m_k ),
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"=d" ( confmem_16m_plus_64k ),
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"=D" ( flags ) ),
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IN_CONSTRAINTS ( "a" ( 0xe801 ),
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"c" ( 0 ),
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"d" ( 0 ) ),
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CLOBBER ( "ebp", "esi" ) );
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if ( ! ( flags & CF ) ) {
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/* INT 15,e801 succeeded */
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if ( confmem_1m_to_16m_k || confmem_16m_plus_64k ) {
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/* Use confmem (cx,dx) values */
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memsize = confmem_1m_to_16m_k +
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( confmem_16m_plus_64k << 6 );
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} else {
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/* Use extmem (ax,bx) values */
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memsize = extmem_1m_to_16m_k +
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( extmem_16m_plus_64k << 6 );
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}
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} else {
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/* INT 15,e801 failed; fall back to INT 15,88
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*
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* CF is apparently unreliable and should be ignored.
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*/
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REAL_EXEC ( rm_mem_88,
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"int $0x15\n\t",
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1,
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OUT_CONSTRAINTS ( "=a" ( extmem_1m_to_16m_k ) ),
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IN_CONSTRAINTS ( "a" ( 0x88 << 8 ) ),
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CLOBBER ( "ebx", "ecx", "edx",
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"ebp", "esi", "edi" ) );
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memsize = extmem_1m_to_16m_k;
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}
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return memsize;
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}
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/**************************************************************************
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MEME820 - Retrieve the E820 BIOS memory map
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**************************************************************************/
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#define SMAP ( 0x534d4150 ) /* "SMAP" */
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static int meme820 ( struct e820entry *buf, int count ) {
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int index;
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uint16_t basemem_entry;
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uint32_t smap, next;
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uint16_t flags;
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uint32_t discard_c, discard_d;
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index = 0;
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next = 0;
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do {
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basemem_entry = BASEMEM_PARAMETER_INIT ( buf[index] );
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REAL_EXEC ( rm_mem_e820,
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"int $0x15\n\t"
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"pushfw\n\t" /* flags -> %di */
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"popw %%di\n\t",
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5,
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OUT_CONSTRAINTS ( "=a" ( smap ),
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"=b" ( next ),
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"=c" ( discard_c ),
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"=d" ( discard_d ),
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"=D" ( flags ) ),
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IN_CONSTRAINTS ( "a" ( 0xe820 ),
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"b" ( next ),
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"c" ( sizeof (struct e820entry) ),
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"d" ( SMAP ),
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"D" ( basemem_entry ) ),
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CLOBBER ( "ebp", "esi" ) );
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BASEMEM_PARAMETER_DONE ( buf[index] );
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if ( smap != SMAP ) return 0;
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if ( flags & CF ) break;
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index++;
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} while ( ( index < count ) && ( next != 0 ) );
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return index;
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}
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/**************************************************************************
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GET_MEMSIZES - Retrieve the system memory map via any available means
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**************************************************************************/
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void get_memsizes ( void ) {
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/* Ensure we don't stomp bios data structutres.
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* the interrupt table: 0x000 - 0x3ff
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* the bios data area: 0x400 - 0x502
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* Dos variables: 0x502 - 0x5ff
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*/
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static const unsigned min_addr = 0x600;
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unsigned i;
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unsigned basemem;
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/* Retrieve memory information from the BIOS */
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meminfo.basememsize = basememsize();
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basemem = meminfo.basememsize << 10;
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meminfo.memsize = memsize();
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#ifndef IGNORE_E820_MAP
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meminfo.map_count = meme820 ( meminfo.map, E820MAX );
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#else
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meminfo.map_count = 0;
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#endif
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/* If we don't have an e820 memory map fake it */
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if ( meminfo.map_count == 0 ) {
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meminfo.map_count = 2;
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meminfo.map[0].addr = 0;
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meminfo.map[0].size = meminfo.basememsize << 10;
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meminfo.map[0].type = E820_RAM;
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meminfo.map[1].addr = 1024*1024;
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meminfo.map[1].size = meminfo.memsize << 10;
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meminfo.map[1].type = E820_RAM;
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}
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/* Scrub the e820 map */
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for ( i = 0; i < meminfo.map_count; i++ ) {
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if ( meminfo.map[i].type != E820_RAM ) {
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continue;
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}
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/* Reserve the bios data structures */
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if ( meminfo.map[i].addr < min_addr ) {
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unsigned long delta;
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delta = min_addr - meminfo.map[i].addr;
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if ( delta > meminfo.map[i].size ) {
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delta = meminfo.map[i].size;
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}
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meminfo.map[i].addr = min_addr;
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meminfo.map[i].size -= delta;
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}
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/* Ensure the returned e820 map is in sync with the
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* actual memory state
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*/
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if ( ( meminfo.map[i].addr < 0xa0000 ) &&
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(( meminfo.map[i].addr+meminfo.map[i].size ) > basemem )){
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if ( meminfo.map[i].addr <= basemem ) {
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meminfo.map[i].size = basemem
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- meminfo.map[i].addr;
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} else {
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meminfo.map[i].addr = basemem;
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meminfo.map[i].size = 0;
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}
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}
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}
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#ifdef DEBUG_MEMSIZES
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printf ( "basememsize %d\n", meminfo.basememsize );
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printf ( "memsize %d\n", meminfo.memsize );
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printf ( "Memory regions(%d):\n", meminfo.map_count );
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for ( i = 0; i < meminfo.map_count; i++ ) {
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unsigned long long r_start, r_end;
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r_start = meminfo.map[i].addr;
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r_end = r_start + meminfo.map[i].size;
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printf ( "[%X%X, %X%X) type %d\n",
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( unsigned long ) ( r_start >> 32 ),
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( unsigned long ) r_start,
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( unsigned long ) ( r_end >> 32 ),
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( unsigned long ) r_end,
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meminfo.map[i].type );
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}
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#endif
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}
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INIT_FN ( INIT_MEMSIZES, get_memsizes, NULL, NULL );
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