2 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 FILE_LICENCE ( GPL2_OR_LATER );
36 /** Magic value for INT 15,e820 calls */
37 #define SMAP ( 0x534d4150 )
39 /** An INT 15,e820 memory map entry */
41 /** Start of region */
43 /** Length of region */
47 /** Extended attributes (optional) */
49 } __attribute__ (( packed ));
51 #define E820_TYPE_RAM 1 /**< Normal memory */
52 #define E820_TYPE_RESERVED 2 /**< Reserved and unavailable */
53 #define E820_TYPE_ACPI 3 /**< ACPI reclaim memory */
54 #define E820_TYPE_NVS 4 /**< ACPI NVS memory */
56 #define E820_ATTR_ENABLED 0x00000001UL
57 #define E820_ATTR_NONVOLATILE 0x00000002UL
58 #define E820_ATTR_UNKNOWN 0xfffffffcUL
60 #define E820_MIN_SIZE 20
62 /** Buffer for INT 15,e820 calls */
63 static struct e820_entry __bss16 ( e820buf );
64 #define e820buf __use_data16 ( e820buf )
66 /** We are running during POST; inhibit INT 15,e820 and INT 15,e801 */
67 uint8_t __bss16 ( memmap_post );
68 #define memmap_post __use_data16 ( memmap_post )
71 * Get size of extended memory via INT 15,e801
73 * @ret extmem Extended memory size, in kB, or 0
75 static unsigned int extmemsize_e801 ( void ) {
76 uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
77 uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
81 /* Inhibit INT 15,e801 during POST */
83 DBG ( "INT 15,e801 not available during POST\n" );
87 __asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
92 "=a" ( extmem_1m_to_16m_k ),
93 "=b" ( extmem_16m_plus_64k ),
94 "=c" ( confmem_1m_to_16m_k ),
95 "=d" ( confmem_16m_plus_64k )
99 DBG ( "INT 15,e801 failed with CF set\n" );
103 if ( ! ( extmem_1m_to_16m_k | extmem_16m_plus_64k ) ) {
104 DBG ( "INT 15,e801 extmem=0, using confmem\n" );
105 extmem_1m_to_16m_k = confmem_1m_to_16m_k;
106 extmem_16m_plus_64k = confmem_16m_plus_64k;
109 extmem = ( extmem_1m_to_16m_k + ( extmem_16m_plus_64k * 64 ) );
110 DBG ( "INT 15,e801 extended memory size %d+64*%d=%d kB "
111 "[100000,%llx)\n", extmem_1m_to_16m_k, extmem_16m_plus_64k,
112 extmem, ( 0x100000 + ( ( ( uint64_t ) extmem ) * 1024 ) ) );
114 /* Sanity check. Some BIOSes report the entire 4GB address
115 * space as available, which cannot be correct (since that
116 * would leave no address space available for 32-bit PCI
119 if ( extmem == ( 0x400000 - 0x400 ) ) {
120 DBG ( "INT 15,e801 reported whole 4GB; assuming insane\n" );
128 * Get size of extended memory via INT 15,88
130 * @ret extmem Extended memory size, in kB
132 static unsigned int extmemsize_88 ( void ) {
135 /* Ignore CF; it is not reliable for this call */
136 __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
137 : "=a" ( extmem ) : "a" ( 0x8800 ) );
139 DBG ( "INT 15,88 extended memory size %d kB [100000, %x)\n",
140 extmem, ( 0x100000 + ( extmem * 1024 ) ) );
145 * Get size of extended memory
147 * @ret extmem Extended memory size, in kB
149 * Note that this is only an approximation; for an accurate picture,
150 * use the E820 memory map obtained via get_memmap();
152 unsigned int extmemsize ( void ) {
153 unsigned int extmem_e801;
154 unsigned int extmem_88;
156 /* Try INT 15,e801 first, then fall back to INT 15,88 */
157 extmem_88 = extmemsize_88();
158 extmem_e801 = extmemsize_e801();
159 return ( extmem_e801 ? extmem_e801 : extmem_88 );
163 * Get e820 memory map
165 * @v memmap Memory map to fill in
166 * @ret rc Return status code
168 static int meme820 ( struct memory_map *memmap ) {
169 struct memory_region *region = memmap->regions;
170 struct memory_region *prev_region = NULL;
175 unsigned int discard_D;
177 /* Inhibit INT 15,e820 during POST */
179 DBG ( "INT 15,e820 not available during POST\n" );
183 /* Clear the E820 buffer. Do this once before starting,
184 * rather than on each call; some BIOSes rely on the contents
185 * being preserved between calls.
187 memset ( &e820buf, 0, sizeof ( e820buf ) );
190 /* Some BIOSes corrupt %esi for fun. Guard against
191 * this by telling gcc that all non-output registers
194 __asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t"
200 : "=a" ( smap ), "=b" ( next ),
201 "=c" ( size ), "=d" ( flags ),
203 : "a" ( 0xe820 ), "b" ( next ),
204 "D" ( __from_data16 ( &e820buf ) ),
205 "c" ( sizeof ( e820buf ) ),
209 if ( smap != SMAP ) {
210 DBG ( "INT 15,e820 failed SMAP signature check\n" );
214 if ( size < E820_MIN_SIZE ) {
215 DBG ( "INT 15,e820 returned only %zd bytes\n", size );
220 DBG ( "INT 15,e820 terminated on CF set\n" );
224 /* If first region is not RAM, assume map is invalid */
225 if ( ( memmap->count == 0 ) &&
226 ( e820buf.type != E820_TYPE_RAM ) ) {
227 DBG ( "INT 15,e820 failed, first entry not RAM\n" );
231 DBG ( "INT 15,e820 region [%llx,%llx) type %d",
232 e820buf.start, ( e820buf.start + e820buf.len ),
233 ( int ) e820buf.type );
234 if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
235 DBG ( " (%s", ( ( e820buf.attrs & E820_ATTR_ENABLED )
236 ? "enabled" : "disabled" ) );
237 if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
238 DBG ( ", non-volatile" );
239 if ( e820buf.attrs & E820_ATTR_UNKNOWN )
240 DBG ( ", other [%08x]", e820buf.attrs );
245 /* Discard non-RAM regions */
246 if ( e820buf.type != E820_TYPE_RAM )
249 /* Check extended attributes, if present */
250 if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
251 if ( ! ( e820buf.attrs & E820_ATTR_ENABLED ) )
253 if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
257 region->start = e820buf.start;
258 region->end = e820buf.start + e820buf.len;
260 /* Check for adjacent regions and merge them */
261 if ( prev_region && ( region->start == prev_region->end ) ) {
262 prev_region->end = region->end;
264 prev_region = region;
269 if ( memmap->count >= ( sizeof ( memmap->regions ) /
270 sizeof ( memmap->regions[0] ) ) ) {
271 DBG ( "INT 15,e820 too many regions returned\n" );
272 /* Not a fatal error; what we've got so far at
273 * least represents valid regions of memory,
274 * even if we couldn't get them all.
278 } while ( next != 0 );
280 /* Sanity checks. Some BIOSes report complete garbage via INT
281 * 15,e820 (especially at POST time), despite passing the
282 * signature checks. We currently check for a base memory
283 * region (starting at 0) and at least one high memory region
284 * (starting at 0x100000).
286 if ( memmap->count < 2 ) {
287 DBG ( "INT 15,e820 returned only %d regions; assuming "
288 "insane\n", memmap->count );
291 if ( memmap->regions[0].start != 0 ) {
292 DBG ( "INT 15,e820 region 0 starts at %llx (expected 0); "
293 "assuming insane\n", memmap->regions[0].start );
296 if ( memmap->regions[1].start != 0x100000 ) {
297 DBG ( "INT 15,e820 region 1 starts at %llx (expected 100000); "
298 "assuming insane\n", memmap->regions[0].start );
308 * @v memmap Memory map to fill in
310 void x86_get_memmap ( struct memory_map *memmap ) {
311 unsigned int basemem, extmem;
314 DBG ( "Fetching system memory map\n" );
316 /* Clear memory map */
317 memset ( memmap, 0, sizeof ( *memmap ) );
319 /* Get base and extended memory sizes */
320 basemem = basememsize();
321 DBG ( "FBMS base memory size %d kB [0,%x)\n",
322 basemem, ( basemem * 1024 ) );
323 extmem = extmemsize();
325 /* Try INT 15,e820 first */
326 if ( ( rc = meme820 ( memmap ) ) == 0 ) {
327 DBG ( "Obtained system memory map via INT 15,e820\n" );
331 /* Fall back to constructing a map from basemem and extmem sizes */
332 DBG ( "INT 15,e820 failed; constructing map\n" );
333 memmap->regions[0].end = ( basemem * 1024 );
334 memmap->regions[1].start = 0x100000;
335 memmap->regions[1].end = 0x100000 + ( extmem * 1024 );
339 PROVIDE_IOAPI ( x86, get_memmap, x86_get_memmap );