141 lines
3.3 KiB
C
141 lines
3.3 KiB
C
/* -*- linux-c -*- ------------------------------------------------------- *
|
|
*
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
* Copyright 2007 rPath, Inc. - All Rights Reserved
|
|
* Copyright 2009 Intel Corporation; author H. Peter Anvin
|
|
*
|
|
* This file is part of the Linux kernel, and is made available under
|
|
* the terms of the GNU General Public License version 2.
|
|
*
|
|
* ----------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Memory detection code
|
|
*/
|
|
|
|
#include "boot.h"
|
|
|
|
#define SMAP 0x534d4150 /* ASCII "SMAP" */
|
|
|
|
struct e820_ext_entry {
|
|
struct e820entry std;
|
|
u32 ext_flags;
|
|
} __attribute__((packed));
|
|
|
|
static int detect_memory_e820(void)
|
|
{
|
|
int count = 0;
|
|
u32 next = 0;
|
|
u32 size, id, edi;
|
|
u8 err;
|
|
struct e820entry *desc = boot_params.e820_map;
|
|
static struct e820_ext_entry buf; /* static so it is zeroed */
|
|
|
|
/*
|
|
* Set this here so that if the BIOS doesn't change this field
|
|
* but still doesn't change %ecx, we're still okay...
|
|
*/
|
|
buf.ext_flags = 1;
|
|
|
|
do {
|
|
size = sizeof buf;
|
|
|
|
/* Important: %edx and %esi are clobbered by some BIOSes,
|
|
so they must be either used for the error output
|
|
or explicitly marked clobbered. Given that, assume there
|
|
is something out there clobbering %ebp and %edi, too. */
|
|
asm("pushl %%ebp; int $0x15; popl %%ebp; setc %0"
|
|
: "=d" (err), "+b" (next), "=a" (id), "+c" (size),
|
|
"=D" (edi), "+m" (buf)
|
|
: "D" (&buf), "d" (SMAP), "a" (0xe820)
|
|
: "esi");
|
|
|
|
/* BIOSes which terminate the chain with CF = 1 as opposed
|
|
to %ebx = 0 don't always report the SMAP signature on
|
|
the final, failing, probe. */
|
|
if (err)
|
|
break;
|
|
|
|
/* Some BIOSes stop returning SMAP in the middle of
|
|
the search loop. We don't know exactly how the BIOS
|
|
screwed up the map at that point, we might have a
|
|
partial map, the full map, or complete garbage, so
|
|
just return failure. */
|
|
if (id != SMAP) {
|
|
count = 0;
|
|
break;
|
|
}
|
|
|
|
/* ACPI 3.0 added the extended flags support. If bit 0
|
|
in the extended flags is zero, we're supposed to simply
|
|
ignore the entry -- a backwards incompatible change! */
|
|
if (size > 20 && !(buf.ext_flags & 1))
|
|
continue;
|
|
|
|
*desc++ = buf.std;
|
|
count++;
|
|
} while (next && count < ARRAY_SIZE(boot_params.e820_map));
|
|
|
|
return boot_params.e820_entries = count;
|
|
}
|
|
|
|
static int detect_memory_e801(void)
|
|
{
|
|
u16 ax, bx, cx, dx;
|
|
u8 err;
|
|
|
|
bx = cx = dx = 0;
|
|
ax = 0xe801;
|
|
asm("stc; int $0x15; setc %0"
|
|
: "=m" (err), "+a" (ax), "+b" (bx), "+c" (cx), "+d" (dx));
|
|
|
|
if (err)
|
|
return -1;
|
|
|
|
/* Do we really need to do this? */
|
|
if (cx || dx) {
|
|
ax = cx;
|
|
bx = dx;
|
|
}
|
|
|
|
if (ax > 15*1024)
|
|
return -1; /* Bogus! */
|
|
|
|
/* This ignores memory above 16MB if we have a memory hole
|
|
there. If someone actually finds a machine with a memory
|
|
hole at 16MB and no support for 0E820h they should probably
|
|
generate a fake e820 map. */
|
|
boot_params.alt_mem_k = (ax == 15*1024) ? (dx << 6)+ax : ax;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int detect_memory_88(void)
|
|
{
|
|
u16 ax;
|
|
u8 err;
|
|
|
|
ax = 0x8800;
|
|
asm("stc; int $0x15; setc %0" : "=bcdm" (err), "+a" (ax));
|
|
|
|
boot_params.screen_info.ext_mem_k = ax;
|
|
|
|
return -err;
|
|
}
|
|
|
|
int detect_memory(void)
|
|
{
|
|
int err = -1;
|
|
|
|
if (detect_memory_e820() > 0)
|
|
err = 0;
|
|
|
|
if (!detect_memory_e801())
|
|
err = 0;
|
|
|
|
if (!detect_memory_88())
|
|
err = 0;
|
|
|
|
return err;
|
|
}
|