1 /* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of the GNU General Public License as
5 * published by the Free Software Foundation; either version 2 of the
6 * License, or any later version.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software
15 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
16 */
17
18 FILE_LICENCE ( GPL2_OR_LATER );
19
20 #include <realmode.h>
21 #include <biosint.h>
22
23 /** Assembly routine in inline asm */
24 extern void int15_fakee820();
25
26 /** Original INT 15 handler */
27 static struct segoff __text16 ( real_int15_vector );
28 #define real_int15_vector __use_text16 ( real_int15_vector )
29
30 /** An INT 15,e820 memory map entry */
31 struct e820_entry {
32 /** Start of region */
33 uint64_t start;
34 /** Length of region */
35 uint64_t len;
36 /** Type of region */
37 uint32_t type;
38 } __attribute__ (( packed ));
39
40 #define E820_TYPE_RAM 1 /**< Normal memory */
41 #define E820_TYPE_RSVD 2 /**< Reserved and unavailable */
42 #define E820_TYPE_ACPI 3 /**< ACPI reclaim memory */
43 #define E820_TYPE_NVS 4 /**< ACPI NVS memory */
44
45 /** Fake e820 map */
46 static struct e820_entry __text16_array ( e820map, [] ) __used = {
47 { 0x00000000ULL, ( 0x000a0000ULL - 0x00000000ULL ), E820_TYPE_RAM },
48 { 0x00100000ULL, ( 0xcfb50000ULL - 0x00100000ULL ), E820_TYPE_RAM },
49 { 0xcfb50000ULL, ( 0xcfb64000ULL - 0xcfb50000ULL ), E820_TYPE_RSVD },
50 { 0xcfb64000ULL, ( 0xcfb66000ULL - 0xcfb64000ULL ), E820_TYPE_RSVD },
51 { 0xcfb66000ULL, ( 0xcfb85c00ULL - 0xcfb66000ULL ), E820_TYPE_ACPI },
52 { 0xcfb85c00ULL, ( 0xd0000000ULL - 0xcfb85c00ULL ), E820_TYPE_RSVD },
53 { 0xe0000000ULL, ( 0xf0000000ULL - 0xe0000000ULL ), E820_TYPE_RSVD },
54 { 0xfe000000ULL, (0x100000000ULL - 0xfe000000ULL ), E820_TYPE_RSVD },
55 {0x100000000ULL, (0x230000000ULL -0x100000000ULL ), E820_TYPE_RAM },
56 };
57 #define e820map __use_text16 ( e820map )
58
fake_e820(void)59 void fake_e820 ( void ) {
60 __asm__ __volatile__ (
61 TEXT16_CODE ( "\nint15_fakee820:\n\t"
62 "pushfw\n\t"
63 "cmpl $0xe820, %%eax\n\t"
64 "jne 99f\n\t"
65 "cmpl $0x534d4150, %%edx\n\t"
66 "jne 99f\n\t"
67 "pushaw\n\t"
68 "movw %%sp, %%bp\n\t"
69 "andb $~0x01, 22(%%bp)\n\t" /* Clear return CF */
70 "leaw e820map(%%bx), %%si\n\t"
71 "cs rep movsb\n\t"
72 "popaw\n\t"
73 "movl %%edx, %%eax\n\t"
74 "addl $20, %%ebx\n\t"
75 "cmpl %0, %%ebx\n\t"
76 "jne 1f\n\t"
77 "xorl %%ebx,%%ebx\n\t"
78 "\n1:\n\t"
79 "popfw\n\t"
80 "iret\n\t"
81 "\n99:\n\t"
82 "popfw\n\t"
83 "ljmp *%%cs:real_int15_vector\n\t" )
84 : : "i" ( sizeof ( e820map ) ) );
85
86 hook_bios_interrupt ( 0x15, ( unsigned int ) int15_fakee820,
87 &real_int15_vector );
88 }
89
unfake_e820(void)90 void unfake_e820 ( void ) {
91 unhook_bios_interrupt ( 0x15, ( unsigned int ) int15_fakee820,
92 &real_int15_vector );
93 }
94