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/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* memmap.c
*
* Create initial memory map for "shuffle and boot" operation
*/
#include <assert.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <inttypes.h>
#include <setjmp.h>
#include <string.h>
#include <com32.h>
#include <syslinux/movebits.h>
struct e820_entry {
uint64_t start;
uint64_t len;
uint32_t type;
uint32_t extattr;
};
struct syslinux_memmap *syslinux_memory_map(void)
{
static com32sys_t ireg, zireg;
com32sys_t oreg;
struct e820_entry *e820buf = __com32.cs_bounce;
uint64_t start, len, maxlen;
int memfound = 0;
struct syslinux_memmap *mmap;
enum syslinux_memmap_types type;
mmap = syslinux_init_memmap();
if (!mmap)
goto bail;
/* Use INT 12h to get DOS memory above 0x7c00 */
__intcall(0x12, &zireg, &oreg);
if (oreg.eax.w[0] > 31 && oreg.eax.w[0] <= 640) {
addr_t dosmem = (oreg.eax.w[0] << 10) - 0x7c00;
if (syslinux_add_memmap(&mmap, 0x7c00, dosmem, SMT_FREE))
goto bail;
}
/* First try INT 15h AX=E820h */
ireg.eax.l = 0xe820;
ireg.edx.l = 0x534d4150;
ireg.ebx.l = 0;
ireg.ecx.l = sizeof(*e820buf);
ireg.es = SEG(e820buf);
ireg.edi.w[0] = OFFS(e820buf);
do {
__intcall(0x15, &ireg, &oreg);
if ((oreg.eflags.l & EFLAGS_CF) ||
(oreg.eax.l != 0x534d4150) ||
(oreg.ecx.l < 20))
break;
if (oreg.ecx.l < 24)
e820buf->extattr = 1; /* Enabled, normal */
if (!(e820buf->extattr & 1))
continue;
type = e820buf->type == 1 ? SMT_FREE : SMT_RESERVED;
start = e820buf->start;
len = e820buf->len;
if (start < 0x100000000ULL) {
/* Don't rely on E820 being valid for low memory. Doing so
could mean stuff like overwriting the PXE stack even when
using "keeppxe", etc. */
if (start < 0x100000ULL) {
if (len > 0x100000ULL-start)
len -= 0x100000ULL-start;
else
len = 0;
start = 0x100000ULL;
}
maxlen = 0x100000000ULL-start;
if (len > maxlen)
len = maxlen;
if (len) {
if (syslinux_add_memmap(&mmap, (addr_t)start, (addr_t)len, type))
goto bail;
memfound = 1;
}
}
ireg.ebx.l = oreg.ebx.l;
} while (oreg.ebx.l);
if (memfound)
return mmap;
/* Next try INT 15h AX=E801h */
ireg.eax.w[0] = 0xe801;
__intcall(0x15, &ireg, &oreg);
if (!(oreg.eflags.l & EFLAGS_CF) && oreg.ecx.w[0]) {
if (syslinux_add_memmap(&mmap, (addr_t)1 << 20, oreg.ecx.w[0] << 10,
SMT_FREE))
goto bail;
if (oreg.edx.w[0]) {
if (syslinux_add_memmap(&mmap, (addr_t)16 << 20, oreg.edx.w[0] << 16,
SMT_FREE))
goto bail;
}
return mmap;
}
/* Finally try INT 15h AH=88h */
ireg.eax.w[0] = 0x8800;
if (!(oreg.eflags.l & EFLAGS_CF) && oreg.eax.w[0]) {
if (syslinux_add_memmap(&mmap, (addr_t)1 << 20, oreg.ecx.w[0] << 10,
SMT_FREE))
goto bail;
}
return mmap;
bail:
syslinux_free_memmap(mmap);
return NULL;
}
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