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-rw-r--r--src/arch/x86/interface/pcbios/int15.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/src/arch/x86/interface/pcbios/int15.c b/src/arch/x86/interface/pcbios/int15.c
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+++ b/src/arch/x86/interface/pcbios/int15.c
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+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <realmode.h>
+#include <bios.h>
+#include <memsizes.h>
+#include <ipxe/io.h>
+#include <ipxe/memmap.h>
+
+/**
+ * @file
+ *
+ * Memory mapping
+ *
+ */
+
+/** Magic value for INT 15,e820 calls */
+#define SMAP ( 0x534d4150 )
+
+/** An INT 15,e820 memory map entry */
+struct e820_entry {
+ /** Start of region */
+ uint64_t start;
+ /** Length of region */
+ uint64_t len;
+ /** Type of region */
+ uint32_t type;
+ /** Extended attributes (optional) */
+ uint32_t attrs;
+} __attribute__ (( packed ));
+
+#define E820_TYPE_RAM 1 /**< Normal memory */
+#define E820_TYPE_RESERVED 2 /**< Reserved and unavailable */
+#define E820_TYPE_ACPI 3 /**< ACPI reclaim memory */
+#define E820_TYPE_NVS 4 /**< ACPI NVS memory */
+
+#define E820_ATTR_ENABLED 0x00000001UL
+#define E820_ATTR_NONVOLATILE 0x00000002UL
+#define E820_ATTR_UNKNOWN 0xfffffffcUL
+
+#define E820_MIN_SIZE 20
+
+/** Buffer for INT 15,e820 calls */
+static struct e820_entry __bss16 ( e820buf );
+#define e820buf __use_data16 ( e820buf )
+
+/** We are running during POST; inhibit INT 15,e820 and INT 15,e801 */
+uint8_t __bss16 ( memmap_post );
+#define memmap_post __use_data16 ( memmap_post )
+
+/**
+ * Get size of extended memory via INT 15,e801
+ *
+ * @ret extmem Extended memory size, in kB, or 0
+ */
+static unsigned int extmemsize_e801 ( void ) {
+ uint16_t extmem_1m_to_16m_k, extmem_16m_plus_64k;
+ uint16_t confmem_1m_to_16m_k, confmem_16m_plus_64k;
+ unsigned int flags;
+ unsigned int extmem;
+
+ /* Inhibit INT 15,e801 during POST */
+ if ( memmap_post ) {
+ DBG ( "INT 15,e801 not available during POST\n" );
+ return 0;
+ }
+
+ __asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
+ "int $0x15\n\t"
+ "pushfw\n\t"
+ "popw %w0\n\t" )
+ : "=R" ( flags ),
+ "=a" ( extmem_1m_to_16m_k ),
+ "=b" ( extmem_16m_plus_64k ),
+ "=c" ( confmem_1m_to_16m_k ),
+ "=d" ( confmem_16m_plus_64k )
+ : "a" ( 0xe801 ) );
+
+ if ( flags & CF ) {
+ DBG ( "INT 15,e801 failed with CF set\n" );
+ return 0;
+ }
+
+ if ( ! ( extmem_1m_to_16m_k | extmem_16m_plus_64k ) ) {
+ DBG ( "INT 15,e801 extmem=0, using confmem\n" );
+ extmem_1m_to_16m_k = confmem_1m_to_16m_k;
+ extmem_16m_plus_64k = confmem_16m_plus_64k;
+ }
+
+ extmem = ( extmem_1m_to_16m_k + ( extmem_16m_plus_64k * 64 ) );
+ DBG ( "INT 15,e801 extended memory size %d+64*%d=%d kB "
+ "[100000,%llx)\n", extmem_1m_to_16m_k, extmem_16m_plus_64k,
+ extmem, ( 0x100000 + ( ( ( uint64_t ) extmem ) * 1024 ) ) );
+
+ /* Sanity check. Some BIOSes report the entire 4GB address
+ * space as available, which cannot be correct (since that
+ * would leave no address space available for 32-bit PCI
+ * BARs).
+ */
+ if ( extmem == ( 0x400000 - 0x400 ) ) {
+ DBG ( "INT 15,e801 reported whole 4GB; assuming insane\n" );
+ return 0;
+ }
+
+ return extmem;
+}
+
+/**
+ * Get size of extended memory via INT 15,88
+ *
+ * @ret extmem Extended memory size, in kB
+ */
+static unsigned int extmemsize_88 ( void ) {
+ uint16_t extmem;
+
+ /* Ignore CF; it is not reliable for this call */
+ __asm__ __volatile__ ( REAL_CODE ( "int $0x15" )
+ : "=a" ( extmem ) : "a" ( 0x8800 ) );
+
+ DBG ( "INT 15,88 extended memory size %d kB [100000, %x)\n",
+ extmem, ( 0x100000 + ( extmem * 1024 ) ) );
+ return extmem;
+}
+
+/**
+ * Get size of extended memory
+ *
+ * @ret extmem Extended memory size, in kB
+ *
+ * Note that this is only an approximation; for an accurate picture,
+ * use the E820 memory map obtained via memmap_describe();
+ */
+unsigned int extmemsize ( void ) {
+ unsigned int extmem_e801;
+ unsigned int extmem_88;
+
+ /* Try INT 15,e801 first, then fall back to INT 15,88 */
+ extmem_88 = extmemsize_88();
+ extmem_e801 = extmemsize_e801();
+ return ( extmem_e801 ? extmem_e801 : extmem_88 );
+}
+
+/**
+ * Get e820 memory map
+ *
+ * @v region Memory region of interest to be updated
+ * @ret rc Return status code
+ */
+static int meme820 ( struct memmap_region *region ) {
+ unsigned int count = 0;
+ uint64_t start = 0;
+ uint64_t len = 0;
+ uint32_t next = 0;
+ uint32_t smap;
+ uint32_t size;
+ unsigned int flags;
+ unsigned int discard_D;
+
+ /* Inhibit INT 15,e820 during POST */
+ if ( memmap_post ) {
+ DBG ( "INT 15,e820 not available during POST\n" );
+ return -ENOTTY;
+ }
+
+ /* Clear the E820 buffer. Do this once before starting,
+ * rather than on each call; some BIOSes rely on the contents
+ * being preserved between calls.
+ */
+ memset ( &e820buf, 0, sizeof ( e820buf ) );
+
+ do {
+ /* Some BIOSes corrupt %esi for fun. Guard against
+ * this by telling gcc that all non-output registers
+ * may be corrupted.
+ */
+ __asm__ __volatile__ ( REAL_CODE ( "pushl %%ebp\n\t"
+ "stc\n\t"
+ "int $0x15\n\t"
+ "pushfw\n\t"
+ "popw %%dx\n\t"
+ "popl %%ebp\n\t" )
+ : "=a" ( smap ), "=b" ( next ),
+ "=c" ( size ), "=d" ( flags ),
+ "=D" ( discard_D )
+ : "a" ( 0xe820 ), "b" ( next ),
+ "D" ( __from_data16 ( &e820buf ) ),
+ "c" ( sizeof ( e820buf ) ),
+ "d" ( SMAP )
+ : "esi", "memory" );
+
+ if ( smap != SMAP ) {
+ DBG ( "INT 15,e820 failed SMAP signature check\n" );
+ return -ENOTSUP;
+ }
+
+ if ( size < E820_MIN_SIZE ) {
+ DBG ( "INT 15,e820 returned only %d bytes\n", size );
+ return -EINVAL;
+ }
+
+ if ( flags & CF ) {
+ DBG ( "INT 15,e820 terminated on CF set\n" );
+ break;
+ }
+
+ DBG ( "INT 15,e820 region [%llx,%llx) type %d",
+ e820buf.start, ( e820buf.start + e820buf.len ),
+ ( int ) e820buf.type );
+ if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
+ DBG ( " (%s", ( ( e820buf.attrs & E820_ATTR_ENABLED )
+ ? "enabled" : "disabled" ) );
+ if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
+ DBG ( ", non-volatile" );
+ if ( e820buf.attrs & E820_ATTR_UNKNOWN )
+ DBG ( ", other [%08x]", e820buf.attrs );
+ DBG ( ")" );
+ }
+ DBG ( "\n" );
+
+ /* Discard non-RAM regions */
+ if ( e820buf.type != E820_TYPE_RAM )
+ continue;
+
+ /* Check extended attributes, if present */
+ if ( size > offsetof ( typeof ( e820buf ), attrs ) ) {
+ if ( ! ( e820buf.attrs & E820_ATTR_ENABLED ) )
+ continue;
+ if ( e820buf.attrs & E820_ATTR_NONVOLATILE )
+ continue;
+ }
+
+ /* Check for adjacent regions and merge them */
+ if ( e820buf.start == ( start + len ) ) {
+ len += e820buf.len;
+ } else {
+ start = e820buf.start;
+ len = e820buf.len;
+ }
+
+ /* Sanity check: first region (base memory) should
+ * start at address zero.
+ */
+ if ( ( count == 0 ) && ( start != 0 ) ) {
+ DBG ( "INT 15,e820 region 0 starts at %llx (expected "
+ "0); assuming insane\n", start );
+ return -EINVAL;
+ }
+
+ /* Sanity check: second region (extended memory)
+ * should start at address 0x100000.
+ */
+ if ( ( count == 1 ) && ( start != 0x100000 ) ) {
+ DBG ( "INT 15,e820 region 1 starts at %llx (expected "
+ "100000); assuming insane\n", start );
+ return -EINVAL;
+ }
+
+ /* Update region of interest */
+ memmap_update ( region, start, len, MEMMAP_FL_MEMORY, "e820" );
+ count++;
+
+ } while ( next != 0 );
+
+ /* Sanity checks. Some BIOSes report complete garbage via INT
+ * 15,e820 (especially at POST time), despite passing the
+ * signature checks. We currently check for a base memory
+ * region (starting at 0) and at least one high memory region
+ * (starting at 0x100000).
+ */
+ if ( count < 2 ) {
+ DBG ( "INT 15,e820 returned only %d regions; assuming "
+ "insane\n", count );
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * Describe memory region from system memory map
+ *
+ * @v min Minimum address
+ * @v hide Hide in-use regions from the memory map
+ * @v region Region descriptor to fill in
+ */
+static void int15_describe ( uint64_t min, int hide,
+ struct memmap_region *region ) {
+ unsigned int basemem;
+ unsigned int extmem;
+ uint64_t inaccessible;
+ int rc;
+
+ /* Initialise region */
+ memmap_init ( min, region );
+
+ /* Mark addresses above 4GB as inaccessible: we have no way to
+ * access them either in a 32-bit build or in a 64-bit build
+ * (since the 64-bit build identity-maps only the 32-bit
+ * address space).
+ */
+ inaccessible = ( 1ULL << 32 );
+ memmap_update ( region, inaccessible, -inaccessible,
+ MEMMAP_FL_INACCESSIBLE, NULL );
+
+ /* Enable/disable INT 15 interception as applicable */
+ int15_intercept ( hide );
+
+ /* Try INT 15,e820 first, falling back to constructing a map
+ * from basemem and extmem sizes
+ */
+ if ( ( rc = meme820 ( region ) ) == 0 ) {
+ DBG ( "Obtained system memory map via INT 15,e820\n" );
+ } else {
+ basemem = basememsize();
+ DBG ( "FBMS base memory size %d kB [0,%x)\n",
+ basemem, ( basemem * 1024 ) );
+ extmem = extmemsize();
+ memmap_update ( region, 0, ( basemem * 1024 ),
+ MEMMAP_FL_MEMORY, "basemem" );
+ memmap_update ( region, 0x100000, ( extmem * 1024 ),
+ MEMMAP_FL_MEMORY, "extmem" );
+ }
+
+ /* Restore INT 15 interception */
+ int15_intercept ( 1 );
+}
+
+PROVIDE_MEMMAP ( int15, memmap_describe, int15_describe );
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2026-03-04 19:18:35 +0100