int15.c File Reference

Memory mapping. More...

#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>

Go to the source code of this file.

Data Structures
struct	e820_entry
	An INT 15,e820 memory map entry. More...

Macros
#define	SMAP   ( 0x534d4150 )
	Magic value for INT 15,e820 calls. More...
#define	E820_TYPE_RAM   1
	Normal memory. More...
#define	E820_TYPE_RESERVED   2
	Reserved and unavailable. More...
#define	E820_TYPE_ACPI   3
	ACPI reclaim memory. More...
#define	E820_TYPE_NVS   4
	ACPI NVS memory. More...
#define	E820_ATTR_ENABLED   0x00000001UL
#define	E820_ATTR_NONVOLATILE   0x00000002UL
#define	E820_ATTR_UNKNOWN   0xfffffffcUL
#define	E820_MIN_SIZE   20
#define	e820buf   __use_data16 ( e820buf )
#define	memmap_post   __use_data16 ( memmap_post )

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static struct e820_entry	__bss16 (e820buf)
	Buffer for INT 15,e820 calls. More...
uint8_t	__bss16 (memmap_post)
	We are running during POST; inhibit INT 15,e820 and INT 15,e801. More...
static unsigned int	extmemsize_e801 (void)
	Get size of extended memory via INT 15,e801. More...
static unsigned int	extmemsize_88 (void)
	Get size of extended memory via INT 15,88. More...
unsigned int	extmemsize (void)
	Get size of extended memory. More...
static int	meme820 (struct memmap_region *region)
	Get e820 memory map. More...
static void	int15_describe (uint64_t min, int hide, struct memmap_region *region)
	Describe memory region from system memory map. More...
	PROVIDE_MEMMAP (int15, memmap_describe, int15_describe)

Detailed Description

Memory mapping.

Definition in file int15.c.

Macro Definition Documentation

SMAP

#define SMAP   ( 0x534d4150 )

Magic value for INT 15,e820 calls.

Definition at line 44 of file int15.c.

E820_TYPE_RAM

#define E820_TYPE_RAM   1

Normal memory.

Definition at line 58 of file int15.c.

E820_TYPE_RESERVED

#define E820_TYPE_RESERVED   2

Reserved and unavailable.

Definition at line 59 of file int15.c.

E820_TYPE_ACPI

#define E820_TYPE_ACPI   3

ACPI reclaim memory.

Definition at line 60 of file int15.c.

E820_TYPE_NVS

#define E820_TYPE_NVS   4

ACPI NVS memory.

Definition at line 61 of file int15.c.

E820_ATTR_ENABLED

#define E820_ATTR_ENABLED   0x00000001UL

Definition at line 63 of file int15.c.

E820_ATTR_NONVOLATILE

#define E820_ATTR_NONVOLATILE   0x00000002UL

Definition at line 64 of file int15.c.

E820_ATTR_UNKNOWN

#define E820_ATTR_UNKNOWN   0xfffffffcUL

Definition at line 65 of file int15.c.

E820_MIN_SIZE

#define E820_MIN_SIZE   20

Definition at line 67 of file int15.c.

e820buf

#define e820buf   __use_data16 ( e820buf )

Definition at line 71 of file int15.c.

memmap_post

#define memmap_post   __use_data16 ( memmap_post )

Definition at line 75 of file int15.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

__bss16() [1/2]

static struct e820_entry __bss16 ( e820buf  )

static

Buffer for INT 15,e820 calls.

__bss16() [2/2]

uint8_t __bss16

(

memmap_post

)

We are running during POST; inhibit INT 15,e820 and INT 15,e801.

extmemsize_e801()

static unsigned int extmemsize_e801 ( void  )

static

Get size of extended memory via INT 15,e801.

Return values

extmem

Extended memory size, in kB, or 0

Definition at line 82 of file int15.c.

                                             {
        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;
}

References __asm__(), __volatile__(), CF, DBG, flags, memmap_post, and REAL_CODE.

Referenced by extmemsize().

extmemsize_88()

static unsigned int extmemsize_88 ( void  )

static

Get size of extended memory via INT 15,88.

Return values

extmem

Extended memory size, in kB

Definition at line 139 of file int15.c.

                                           {
        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;
}

References __asm__(), __volatile__(), DBG, and REAL_CODE.

Referenced by extmemsize().

extmemsize()

unsigned int extmemsize

(

void

)

Get size of extended memory.

Return values

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();

Definition at line 159 of file int15.c.

                                 {
        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 );
}

References extmemsize_88(), and extmemsize_e801().

Referenced by int15_describe(), and nbi_process_segments().

meme820()

static int meme820 ( struct memmap_region *  region )

static

Get e820 memory map.

Parameters

region

Memory region of interest to be updated

Return values

rc	Return status code

Definition at line 175 of file int15.c.

                                                    {
        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;
}

References __asm__(), __from_data16, __volatile__(), e820_entry::attrs, CF, count, DBG, discard_D, E820_ATTR_ENABLED, E820_ATTR_NONVOLATILE, E820_ATTR_UNKNOWN, E820_MIN_SIZE, E820_TYPE_RAM, e820buf, EINVAL, ENOTSUP, ENOTTY, flags, len, MEMMAP_FL_MEMORY, memmap_post, memmap_update(), memset(), next, offsetof, REAL_CODE, size, SMAP, start, and typeof().

Referenced by int15_describe().

int15_describe()

static void int15_describe ( uint64_t  min, int  hide, struct memmap_region *  region  )

static

Describe memory region from system memory map.

Parameters

min	Minimum address
hide	Hide in-use regions from the memory map
region	Region descriptor to fill in

Definition at line 312 of file int15.c.

                                                            {
        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 );
}

References basememsize(), DBG, extmemsize(), int15_intercept(), meme820(), MEMMAP_FL_INACCESSIBLE, MEMMAP_FL_MEMORY, memmap_init(), memmap_update(), min, NULL, and rc.

PROVIDE_MEMMAP()

PROVIDE_MEMMAP	(	int15	,
		memmap_describe	,
		int15_describe
	)