/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
* Copyright 2009 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.
*
* ----------------------------------------------------------------------- */
/*
* mem.c
*
* Obtain a memory map for a Multiboot OS
*
* This differs from the libcom32 memory map functions in that it doesn't
* attempt to filter out memory regions...
*/
#include "mboot.h"
#include <com32.h>
struct e820_entry {
uint64_t start;
uint64_t len;
uint32_t type;
};
#define RANGE_ALLOC_BLOCK 128
static int mboot_scan_memory(struct AddrRangeDesc **ardp, uint32_t * dosmem)
{
com32sys_t ireg, oreg;
struct e820_entry *e820buf = __com32.cs_bounce;
struct AddrRangeDesc *ard;
size_t ard_count, ard_space;
/* Use INT 12h to get DOS memory */
__intcall(0x12, &__com32_zero_regs, &oreg);
*dosmem = oreg.eax.w[0] << 10;
if (*dosmem < 32 * 1024 || *dosmem > 640 * 1024) {
/* INT 12h reports nonsense... now what? */
uint16_t ebda_seg = *(uint16_t *) 0x40e;
if (ebda_seg >= 0x8000 && ebda_seg < 0xa000)
*dosmem = ebda_seg << 4;
else
*dosmem = 640 * 1024; /* Hope for the best... */
}
/* Allocate initial space */
*ardp = ard = malloc(RANGE_ALLOC_BLOCK * sizeof *ard);
if (!ard)
return 0;
ard_count = 0;
ard_space = RANGE_ALLOC_BLOCK;
/* First try INT 15h AX=E820h */
memset(&ireg, 0, sizeof ireg);
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);
memset(e820buf, 0, sizeof *e820buf);
do {
__intcall(0x15, &ireg, &oreg);
if ((oreg.eflags.l & EFLAGS_CF) ||
(oreg.eax.l != 0x534d4150) || (oreg.ecx.l < 20))
break;
if (ard_count >= ard_space) {
ard_space += RANGE_ALLOC_BLOCK;
*ardp = ard = realloc(ard, ard_space * sizeof *ard);
if (!ard)
return ard_count;
}
ard[ard_count].size = 20;
ard[ard_count].BaseAddr = e820buf->start;
ard[ard_count].Length = e820buf->len;
ard[ard_count].Type = e820buf->type;
ard_count++;
ireg.ebx.l = oreg.ebx.l;
} while (oreg.ebx.l);
if (ard_count)
return ard_count;
ard[0].size = 20;
ard[0].BaseAddr = 0;
ard[0].Length = *dosmem << 10;
ard[0].Type = 1;
/* 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]) {
ard[1].size = 20;
ard[1].BaseAddr = 1 << 20;
ard[1].Length = oreg.ecx.w[0] << 10;
ard[1].Type = 1;
if (oreg.edx.w[0]) {
ard[2].size = 20;
ard[2].BaseAddr = 16 << 20;
ard[2].Length = oreg.edx.w[0] << 16;
ard[2].Type = 1;
return 3;
} else {
return 2;
}
}
/* Finally try INT 15h AH=88h */
ireg.eax.w[0] = 0x8800;
if (!(oreg.eflags.l & EFLAGS_CF) && oreg.eax.w[0]) {
ard[1].size = 20;
ard[1].BaseAddr = 1 << 20;
ard[1].Length = oreg.ecx.w[0] << 10;
ard[1].Type = 1;
return 2;
}
return 1; /* ... problematic ... */
}
void mboot_make_memmap(void)
{
int i, nmap;
struct AddrRangeDesc *ard;
uint32_t lowmem, highmem;
uint32_t highrsvd;
/* Always report DOS memory as "lowmem", this may be overly conservative
(e.g. if we're dropping PXE), but it should be *safe*... */
nmap = mboot_scan_memory(&ard, &lowmem);
highmem = 0x100000;
highrsvd = 0xfff00000;
again:
for (i = 0; i < nmap; i++) {
uint64_t start, end;
start = ard[i].BaseAddr;
end = start + ard[i].Length;
if (end < start)
end = ~0ULL;
if (start & 0xffffffff00000000ULL)
continue; /* Not interested in 64-bit memory */
if (start < highmem)
start = highmem;
if (end <= start)
continue;
if (ard[i].Type == 1 && start == highmem) {
highmem = end;
goto again;
} else if (ard[i].Type != 1 && start < highrsvd)
highrsvd = start;
}
if (highmem > highrsvd)
highmem = highrsvd;
mbinfo.mem_lower = lowmem >> 10;
mbinfo.mem_upper = (highmem - 0x100000) >> 10;
mbinfo.flags |= MB_INFO_MEMORY;
/* The spec says this address should be +4, but Grub disagrees */
mbinfo.mmap_addr = map_data(ard, nmap * sizeof *ard, 4, false);
if (mbinfo.mmap_addr) {
mbinfo.mmap_length = nmap * sizeof *ard;
mbinfo.flags |= MB_INFO_MEM_MAP;
}
}
