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[int13] Add support for emulating floppy disk drives 

Tested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2012-03-30 12:05:13 +01:00
parent cf0953a1b0
commit 4dbb193c33
3 changed files with 297 additions and 56 deletions
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1
src/arch/i386/include/bios.h
View File

@ -4,6 +4,7 @@
FILE_LICENCE ( GPL2_OR_LATER );
#define BDA_SEG 0x0040
#define BDA_EQUIPMENT_WORD 0x0010
#define BDA_FBMS 0x0013
#define BDA_NUM_DRIVES 0x0075

52
src/arch/i386/include/int13.h
View File

@ -71,6 +71,19 @@ FILE_LICENCE ( GPL2_OR_LATER );
/** Block size for non-extended INT 13 calls */
#define INT13_BLKSIZE 512
/** @defgroup int13fddtype INT 13 floppy disk drive types
* @{
*/
/** 360K */
#define INT13_FDD_TYPE_360K 0x01
/** 1.2M */
#define INT13_FDD_TYPE_1M2 0x02
/** 720K */
#define INT13_FDD_TYPE_720K 0x03
/** 1.44M */
#define INT13_FDD_TYPE_1M44 0x04
/** An INT 13 disk address packet */
struct int13_disk_address {
/** Size of the packet, in bytes */
@ -394,4 +407,43 @@ enum eltorito_media_type {
ELTORITO_NO_EMULATION = 0,
};
/** A floppy disk geometry */
struct int13_fdd_geometry {
/** Number of tracks */
uint8_t tracks;
/** Number of heads and sectors per track */
uint8_t heads_spt;
};
/** Define a floppy disk geometry */
#define INT13_FDD_GEOMETRY( cylinders, heads, sectors ) \
{ \
.tracks = (cylinders), \
.heads_spt = ( ( (heads) << 6 ) | (sectors) ), \
}
/** Get floppy disk number of cylinders */
#define INT13_FDD_CYLINDERS( geometry ) ( (geometry)->tracks )
/** Get floppy disk number of heads */
#define INT13_FDD_HEADS( geometry ) ( (geometry)->heads_spt >> 6 )
/** Get floppy disk number of sectors per track */
#define INT13_FDD_SECTORS( geometry ) ( (geometry)->heads_spt & 0x3f )
/** A floppy drive parameter table */
struct int13_fdd_parameters {
uint8_t step_rate__head_unload;
uint8_t head_load__ndma;
uint8_t motor_off_delay;
uint8_t bytes_per_sector;
uint8_t sectors_per_track;
uint8_t gap_length;
uint8_t data_length;
uint8_t format_gap_length;
uint8_t format_filler;
uint8_t head_settle_time;
uint8_t motor_start_time;
} __attribute__ (( packed ));
#endif /* INT13_H */

300
src/arch/i386/interface/pcbios/int13.c
View File

@ -75,9 +75,9 @@ struct int13_drive {
/** Underlying block device interface */
struct interface block;
/** BIOS in-use drive number (0x80-0xff) */
/** BIOS in-use drive number (0x00-0xff) */
unsigned int drive;
/** BIOS natural drive number (0x80-0xff)
/** BIOS natural drive number (0x00-0xff)
*
* This is the drive number that would have been assigned by
* 'naturally' appending the drive to the end of the BIOS
@ -142,17 +142,44 @@ static struct segoff __text16 ( int13_vector );
/** Assembly wrapper */
extern void int13_wrapper ( void );
/** Dummy floppy disk parameter table */
static struct int13_fdd_parameters __data16 ( int13_fdd_params ) = {
/* 512 bytes per sector */
.bytes_per_sector = 0x02,
/* Highest sectors per track that we ever return */
.sectors_per_track = 48,
};
#define int13_fdd_params __use_data16 ( int13_fdd_params )
/** List of registered emulated drives */
static LIST_HEAD ( int13s );
/**
* Number of BIOS drives
* Equipment word
*
* Note that this is the number of drives in the system as a whole
* (i.e. a mirror of the counter at 40:75), rather than a count of the
* number of emulated drives.
* This is a cached copy of the BIOS Data Area equipment word at
* 40:10.
*/
static uint8_t num_drives;
static uint16_t equipment_word;
/**
* Number of BIOS floppy disk drives
*
* This is derived from the equipment word. It is held in .text16 to
* allow for easy access by the INT 13,08 wrapper.
*/
static uint8_t __text16 ( num_fdds );
#define num_fdds __use_text16 ( num_fdds )
/**
* Number of BIOS hard disk drives
*
* This is a cached copy of the BIOS Data Area number of hard disk
* drives at 40:75. It is held in .text16 to allow for easy access by
* the INT 13,08 wrapper.
*/
static uint8_t __text16 ( num_drives );
#define num_drives __use_text16 ( num_drives )
/**
* Calculate INT 13 drive sector size
@ -185,6 +212,16 @@ static inline uint32_t int13_capacity32 ( struct int13_drive *int13 ) {
return ( ( capacity <= 0xffffffffUL ) ? capacity : 0xffffffff );
}
/**
* Test if INT 13 drive is a floppy disk drive
*
* @v int13 Emulated drive
* @ret is_fdd Emulated drive is a floppy disk
*/
static inline int int13_is_fdd ( struct int13_drive *int13 ) {
return ( ! ( int13->drive & 0x80 ) );
}
/** An INT 13 command */
struct int13_command {
/** Status */
@ -499,33 +536,33 @@ static int int13_parse_iso9660 ( struct int13_drive *int13, void *scratch ) {
}
/**
* Guess INT 13 drive geometry
* Guess INT 13 hard disk drive geometry
*
* @v int13 Emulated drive
* @v scratch Scratch area for single-sector reads
* @ret heads Guessed number of heads
* @ret sectors Guessed number of sectors per track
* @ret rc Return status code
*
* Guesses the drive geometry by inspecting the partition table.
*/
static int int13_guess_geometry ( struct int13_drive *int13, void *scratch ) {
static int int13_guess_geometry_hdd ( struct int13_drive *int13, void *scratch,
unsigned int *heads,
unsigned int *sectors ) {
struct master_boot_record *mbr = scratch;
struct partition_table_entry *partition;
unsigned int guessed_heads = 255;
unsigned int guessed_sectors_per_track = 63;
unsigned int blocks;
unsigned int blocks_per_cyl;
unsigned int i;
int rc;
/* Don't even try when the blksize is invalid for C/H/S access */
if ( int13_blksize ( int13 ) != INT13_BLKSIZE )
return 0;
/* Default guess is xx/255/63 */
*heads = 255;
*sectors = 63;
/* Read partition table */
if ( ( rc = int13_rw ( int13, 0, 1, virt_to_user ( mbr ),
block_read ) ) != 0 ) {
DBGC ( int13, "INT13 drive %02x could not read partition "
"table to guess geometry: %s\n",
DBGC ( int13, "INT13 drive %02x could not read "
"partition table to guess geometry: %s\n",
int13->drive, strerror ( rc ) );
return rc;
}
@ -534,25 +571,126 @@ static int int13_guess_geometry ( struct int13_drive *int13, void *scratch ) {
DBGC ( int13, "INT13 drive %02x has signature %08x\n",
int13->drive, mbr->signature );
/* Scan through partition table and modify guesses for heads
* and sectors_per_track if we find any used partitions.
/* Scan through partition table and modify guesses for
* heads and sectors_per_track if we find any used
* partitions.
*/
for ( i = 0 ; i < 4 ; i++ ) {
partition = &mbr->partitions[i];
if ( ! partition->type )
continue;
guessed_heads = ( PART_HEAD ( partition->chs_end ) + 1 );
guessed_sectors_per_track = PART_SECTOR ( partition->chs_end );
*heads = ( PART_HEAD ( partition->chs_end ) + 1 );
*sectors = PART_SECTOR ( partition->chs_end );
DBGC ( int13, "INT13 drive %02x guessing C/H/S xx/%d/%d based "
"on partition %d\n", int13->drive, guessed_heads,
guessed_sectors_per_track, ( i + 1 ) );
"on partition %d\n",
int13->drive, *heads, *sectors, ( i + 1 ) );
}
return 0;
}
/** Recognised floppy disk geometries */
static const struct int13_fdd_geometry int13_fdd_geometries[] = {
INT13_FDD_GEOMETRY ( 40, 1, 8 ),
INT13_FDD_GEOMETRY ( 40, 1, 9 ),
INT13_FDD_GEOMETRY ( 40, 2, 8 ),
INT13_FDD_GEOMETRY ( 40, 1, 9 ),
INT13_FDD_GEOMETRY ( 80, 2, 8 ),
INT13_FDD_GEOMETRY ( 80, 2, 9 ),
INT13_FDD_GEOMETRY ( 80, 2, 15 ),
INT13_FDD_GEOMETRY ( 80, 2, 18 ),
INT13_FDD_GEOMETRY ( 80, 2, 20 ),
INT13_FDD_GEOMETRY ( 80, 2, 21 ),
INT13_FDD_GEOMETRY ( 82, 2, 21 ),
INT13_FDD_GEOMETRY ( 83, 2, 21 ),
INT13_FDD_GEOMETRY ( 80, 2, 22 ),
INT13_FDD_GEOMETRY ( 80, 2, 23 ),
INT13_FDD_GEOMETRY ( 80, 2, 24 ),
INT13_FDD_GEOMETRY ( 80, 2, 36 ),
INT13_FDD_GEOMETRY ( 80, 2, 39 ),
INT13_FDD_GEOMETRY ( 80, 2, 40 ),
INT13_FDD_GEOMETRY ( 80, 2, 44 ),
INT13_FDD_GEOMETRY ( 80, 2, 48 ),
};
/**
* Guess INT 13 floppy disk drive geometry
*
* @v int13 Emulated drive
* @ret heads Guessed number of heads
* @ret sectors Guessed number of sectors per track
* @ret rc Return status code
*
* Guesses the drive geometry by inspecting the disk size.
*/
static int int13_guess_geometry_fdd ( struct int13_drive *int13,
unsigned int *heads,
unsigned int *sectors ) {
unsigned int blocks = int13_blksize ( int13 );
const struct int13_fdd_geometry *geometry;
unsigned int cylinders;
unsigned int i;
/* Look for a match against a known geometry */
for ( i = 0 ; i < ( sizeof ( int13_fdd_geometries ) /
sizeof ( int13_fdd_geometries[0] ) ) ; i++ ) {
geometry = &int13_fdd_geometries[i];
cylinders = INT13_FDD_CYLINDERS ( geometry );
*heads = INT13_FDD_HEADS ( geometry );
*sectors = INT13_FDD_SECTORS ( geometry );
if ( ( cylinders * (*heads) * (*sectors) ) == blocks ) {
DBGC ( int13, "INT13 drive %02x guessing C/H/S "
"%d/%d/%d based on size %dK\n", int13->drive,
cylinders, *heads, *sectors, ( blocks / 2 ) );
return 0;
}
}
/* Otherwise, assume a partial disk image in the most common
* format (1440K, 80/2/18).
*/
*heads = 2;
*sectors = 18;
DBGC ( int13, "INT13 drive %02x guessing C/H/S xx/%d/%d based on size "
"%dK\n", int13->drive, *heads, *sectors, ( blocks / 2 ) );
return 0;
}
/**
* Guess INT 13 drive geometry
*
* @v int13 Emulated drive
* @v scratch Scratch area for single-sector reads
* @ret rc Return status code
*/
static int int13_guess_geometry ( struct int13_drive *int13, void *scratch ) {
unsigned int guessed_heads;
unsigned int guessed_sectors;
unsigned int blocks;
unsigned int blocks_per_cyl;
int rc;
/* Don't even try when the blksize is invalid for C/H/S access */
if ( int13_blksize ( int13 ) != INT13_BLKSIZE )
return 0;
/* Guess geometry according to drive type */
if ( int13_is_fdd ( int13 ) ) {
if ( ( rc = int13_guess_geometry_fdd ( int13, &guessed_heads,
&guessed_sectors )) != 0)
return rc;
} else {
if ( ( rc = int13_guess_geometry_hdd ( int13, scratch,
&guessed_heads,
&guessed_sectors )) != 0)
return rc;
}
/* Apply guesses if no geometry already specified */
if ( ! int13->heads )
int13->heads = guessed_heads;
if ( ! int13->sectors_per_track )
int13->sectors_per_track = guessed_sectors_per_track;
int13->sectors_per_track = guessed_sectors;
if ( ! int13->cylinders ) {
/* Avoid attempting a 64-bit divide on a 32-bit system */
blocks = int13_capacity32 ( int13 );
@ -569,19 +707,40 @@ static int int13_guess_geometry ( struct int13_drive *int13, void *scratch ) {
/**
* Update BIOS drive count
*/
static void int13_set_num_drives ( void ) {
static void int13_sync_num_drives ( void ) {
struct int13_drive *int13;
uint8_t *counter;
uint8_t max_drive;
uint8_t required;
/* Get current drive count */
/* Get current drive counts */
get_real ( equipment_word, BDA_SEG, BDA_EQUIPMENT_WORD );
get_real ( num_drives, BDA_SEG, BDA_NUM_DRIVES );
num_fdds = ( ( equipment_word & 0x0001 ) ?
( ( ( equipment_word >> 6 ) & 0x3 ) + 1 ) : 0 );
/* Ensure count is large enough to cover all of our emulated drives */
list_for_each_entry ( int13, &int13s, list ) {
if ( num_drives <= ( int13->drive & 0x7f ) )
num_drives = ( ( int13->drive & 0x7f ) + 1 );
counter = ( int13_is_fdd ( int13 ) ? &num_fdds : &num_drives );
max_drive = int13->drive;
if ( max_drive < int13->natural_drive )
max_drive = int13->natural_drive;
required = ( ( max_drive & 0x7f ) + 1 );
if ( *counter < required ) {
*counter = required;
DBGC ( int13, "INT13 drive %02x added to drive count: "
"%d HDDs, %d FDDs\n",
int13->drive, num_drives, num_fdds );
}
}
/* Update current drive count */
equipment_word &= ~( ( 0x3 << 6 ) | 0x0001 );
if ( num_fdds ) {
equipment_word |= ( 0x0001 |
( ( ( num_fdds - 1 ) & 0x3 ) << 6 ) );
}
put_real ( equipment_word, BDA_SEG, BDA_EQUIPMENT_WORD );
put_real ( num_drives, BDA_SEG, BDA_NUM_DRIVES );
}
@ -589,13 +748,14 @@ static void int13_set_num_drives ( void ) {
* Check number of drives
*/
static void int13_check_num_drives ( void ) {
uint16_t check_equipment_word;
uint8_t check_num_drives;
get_real ( check_equipment_word, BDA_SEG, BDA_EQUIPMENT_WORD );
get_real ( check_num_drives, BDA_SEG, BDA_NUM_DRIVES );
if ( check_num_drives != num_drives ) {
int13_set_num_drives();
DBG ( "INT13 fixing up number of drives from %d to %d\n",
check_num_drives, num_drives );
if ( ( check_equipment_word != equipment_word ) ||
( check_num_drives != num_drives ) ) {
int13_sync_num_drives();
}
}
@ -669,14 +829,19 @@ static int int13_rw_sectors ( struct int13_drive *int13,
int13->drive, int13_blksize ( int13 ) );
return -INT13_STATUS_INVALID;
}
/* Calculate parameters */
cylinder = ( ( ( ix86->regs.cl & 0xc0 ) << 2 ) | ix86->regs.ch );
assert ( cylinder < int13->cylinders );
head = ix86->regs.dh;
assert ( head < int13->heads );
sector = ( ix86->regs.cl & 0x3f );
assert ( ( sector >= 1 ) && ( sector <= int13->sectors_per_track ) );
if ( ( cylinder >= int13->cylinders ) ||
( head >= int13->heads ) ||
( sector < 1 ) || ( sector > int13->sectors_per_track ) ) {
DBGC ( int13, "C/H/S %d/%d/%d out of range for geometry "
"%d/%d/%d\n", cylinder, head, sector, int13->cylinders,
int13->heads, int13->sectors_per_track );
return -INT13_STATUS_INVALID;
}
lba = ( ( ( ( cylinder * int13->heads ) + head )
* int13->sectors_per_track ) + sector - 1 );
count = ix86->regs.al;
@ -761,10 +926,19 @@ static int int13_get_parameters ( struct int13_drive *int13,
return -INT13_STATUS_INVALID;
}
/* Common parameters */
ix86->regs.ch = ( max_cylinder & 0xff );
ix86->regs.cl = ( ( ( max_cylinder >> 8 ) << 6 ) | max_sector );
ix86->regs.dh = max_head;
get_real ( ix86->regs.dl, BDA_SEG, BDA_NUM_DRIVES );
ix86->regs.dl = ( int13_is_fdd ( int13 ) ? num_fdds : num_drives );
/* Floppy-specific parameters */
if ( int13_is_fdd ( int13 ) ) {
ix86->regs.bl = INT13_FDD_TYPE_1M44;
ix86->segs.es = rm_ds;
ix86->regs.di = __from_data16 ( &int13_fdd_params );
}
return 0;
}
@ -781,10 +955,15 @@ static int int13_get_disk_type ( struct int13_drive *int13,
uint32_t blocks;
DBGC2 ( int13, "Get disk type\n" );
blocks = int13_capacity32 ( int13 );
ix86->regs.cx = ( blocks >> 16 );
ix86->regs.dx = ( blocks & 0xffff );
return INT13_DISK_TYPE_HDD;
if ( int13_is_fdd ( int13 ) ) {
return INT13_DISK_TYPE_FDD;
} else {
blocks = int13_capacity32 ( int13 );
ix86->regs.cx = ( blocks >> 16 );
ix86->regs.dx = ( blocks & 0xffff );
return INT13_DISK_TYPE_HDD;
}
}
/**
@ -833,6 +1012,13 @@ static int int13_extended_rw ( struct int13_drive *int13,
userptr_t buffer;
int rc;
/* Extended reads are not allowed on floppy drives.
* ELTORITO.SYS seems to assume that we are really a CD-ROM if
* we support extended reads for a floppy drive.
*/
if ( int13_is_fdd ( int13 ) )
return -INT13_STATUS_INVALID;
/* Get buffer size */
get_real ( bufsize, ix86->segs.ds,
( ix86->regs.si + offsetof ( typeof ( addr ), bufsize ) ) );
@ -1300,26 +1486,29 @@ static void int13_hook_vector ( void ) {
"popw 6(%%bp)\n\t"
/* Fix up %dl:
*
* INT 13,15 : do nothing
* INT 13,15 : do nothing if hard disk
* INT 13,08 : load with number of drives
* all others: restore original value
*/
"cmpb $0x15, -1(%%bp)\n\t"
"je 2f\n\t"
"jne 2f\n\t"
"testb $0x80, -4(%%bp)\n\t"
"jnz 3f\n\t"
"\n2:\n\t"
"movb -4(%%bp), %%dl\n\t"
"cmpb $0x08, -1(%%bp)\n\t"
"jne 2f\n\t"
"pushw %%ds\n\t"
"pushw %1\n\t"
"popw %%ds\n\t"
"movb %c2, %%dl\n\t"
"popw %%ds\n\t"
"jne 3f\n\t"
"testb $0x80, %%dl\n\t"
"movb %%cs:%c1, %%dl\n\t"
"jnz 3f\n\t"
"movb %%cs:%c2, %%dl\n\t"
/* Return */
"\n2:\n\t"
"\n3:\n\t"
"movw %%bp, %%sp\n\t"
"popw %%bp\n\t"
"iret\n\t" )
: : "i" ( int13 ), "i" ( BDA_SEG ), "i" ( BDA_NUM_DRIVES ) );
: : "i" ( int13 ), "i" ( __from_text16 ( &num_drives ) ),
"i" ( __from_text16 ( &num_fdds ) ) );
hook_bios_interrupt ( 0x13, ( unsigned int ) int13_wrapper,
&int13_vector );
@ -1404,14 +1593,13 @@ static void int13_free ( struct refcnt *refcnt ) {
*/
static int int13_hook ( struct uri *uri, unsigned int drive ) {
struct int13_drive *int13;
uint8_t num_drives;
unsigned int natural_drive;
void *scratch;
int rc;
/* Calculate natural drive number */
get_real ( num_drives, BDA_SEG, BDA_NUM_DRIVES );
natural_drive = ( num_drives | 0x80 );
int13_sync_num_drives();
natural_drive = ( ( drive & 0x80 ) ? ( num_drives | 0x80 ) : num_fdds );
/* Check that drive number is not in use */
list_for_each_entry ( int13, &int13s, list ) {
@ -1468,7 +1656,7 @@ static int int13_hook ( struct uri *uri, unsigned int drive ) {
list_add ( &int13->list, &int13s );
/* Update BIOS drive count */
int13_set_num_drives();
int13_sync_num_drives();
free ( scratch );
return 0;