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https://github.com/ipxe/ipxe
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bb41ec385c
Shifting all INT13 drive numbers causes problems on systems that use a sparse drive number space (e.g. qemu BIOS, which uses 0xe0 for the CD-ROM drive). The strategy now is: Each drive is assigned a "natural" drive number, being the next available drive number in the system (based on the BIOS drive count). Each drive is accessed using its specified drive number. If the specified drive number is -1, the natural drive number will be used. Accesses to the specified drive number will be delivered to the emulated drive, masking out any preexisting drive using this number. Accesses to the natural drive number, if different, will be remapped to the masked-out drive. The overall upshot is that, for examples: System has no drives. Emulated INT13 drive gets natural number 0x80 and specified number 0x80. Accesses to drive 0x80 go to the emulated drive, and there is no remapping. System has one drive. Emulated INT13 drive gets natural number 0x81 and specified number 0x80. Accesses to drive 0x80 go to the emulated drive. Accesses to drive 0x81 get remapped to the original drive 0x80.
290 lines
7.3 KiB
C
290 lines
7.3 KiB
C
#ifndef INT13_H
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#define INT13_H
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/** @file
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*
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* INT 13 emulation
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*
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*/
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#include <stdint.h>
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#include <gpxe/list.h>
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struct block_device;
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/**
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* @defgroup int13ops INT 13 operation codes
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* @{
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*/
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/** Reset disk system */
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#define INT13_RESET 0x00
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/** Get status of last operation */
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#define INT13_GET_LAST_STATUS 0x01
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/** Read sectors */
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#define INT13_READ_SECTORS 0x02
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/** Write sectors */
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#define INT13_WRITE_SECTORS 0x03
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/** Get drive parameters */
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#define INT13_GET_PARAMETERS 0x08
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/** Get disk type */
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#define INT13_GET_DISK_TYPE 0x15
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/** Extensions installation check */
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#define INT13_EXTENSION_CHECK 0x41
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/** Extended read */
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#define INT13_EXTENDED_READ 0x42
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/** Extended write */
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#define INT13_EXTENDED_WRITE 0x43
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/** Get extended drive parameters */
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#define INT13_GET_EXTENDED_PARAMETERS 0x48
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/** Get CD-ROM status / terminate emulation */
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#define INT13_CDROM_STATUS_TERMINATE 0x4b
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/** @} */
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/**
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* @defgroup int13status INT 13 status codes
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* @{
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*/
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/** Operation completed successfully */
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#define INT13_STATUS_SUCCESS 0x00
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/** Invalid function or parameter */
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#define INT13_STATUS_INVALID 0x01
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/** Read error */
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#define INT13_STATUS_READ_ERROR 0x04
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/** Write error */
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#define INT13_STATUS_WRITE_ERROR 0xcc
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/** @} */
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/** Block size for non-extended INT 13 calls */
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#define INT13_BLKSIZE 512
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/** An INT 13 emulated drive */
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struct int13_drive {
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/** List of all registered drives */
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struct list_head list;
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/** Underlying block device */
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struct block_device *blockdev;
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/** BIOS in-use drive number (0x80-0xff) */
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unsigned int drive;
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/** BIOS natural drive number (0x80-0xff)
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*
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* This is the drive number that would have been assigned by
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* 'naturally' appending the drive to the end of the BIOS
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* drive list.
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*
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* If the emulated drive replaces a preexisting drive, this is
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* the drive number that the preexisting drive gets remapped
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* to.
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*/
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unsigned int natural_drive;
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/** Number of cylinders
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*
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* The cylinder number field in an INT 13 call is ten bits
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* wide, giving a maximum of 1024 cylinders. Conventionally,
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* when the 7.8GB limit of a CHS address is exceeded, it is
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* the number of cylinders that is increased beyond the
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* addressable limit.
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*/
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unsigned int cylinders;
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/** Number of heads
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*
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* The head number field in an INT 13 call is eight bits wide,
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* giving a maximum of 256 heads. However, apparently all
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* versions of MS-DOS up to and including Win95 fail with 256
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* heads, so the maximum encountered in practice is 255.
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*/
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unsigned int heads;
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/** Number of sectors per track
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*
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* The sector number field in an INT 13 call is six bits wide,
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* giving a maximum of 63 sectors, since sector numbering
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* (unlike head and cylinder numbering) starts at 1, not 0.
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*/
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unsigned int sectors_per_track;
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/** Status of last operation */
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int last_status;
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};
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/** An INT 13 disk address packet */
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struct int13_disk_address {
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/** Size of the packet, in bytes */
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uint8_t bufsize;
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/** Reserved, must be zero */
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uint8_t reserved;
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/** Block count */
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uint16_t count;
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/** Data buffer */
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struct segoff buffer;
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/** Starting block number */
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uint64_t lba;
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/** Data buffer (EDD-3.0 only) */
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uint64_t buffer_phys;
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} __attribute__ (( packed ));
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/** INT 13 disk parameters */
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struct int13_disk_parameters {
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/** Size of this structure */
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uint16_t bufsize;
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/** Flags */
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uint16_t flags;
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/** Number of cylinders */
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uint32_t cylinders;
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/** Number of heads */
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uint32_t heads;
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/** Number of sectors per track */
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uint32_t sectors_per_track;
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/** Total number of sectors on drive */
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uint64_t sectors;
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/** Bytes per sector */
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uint16_t sector_size;
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} __attribute__ (( packed ));
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/**
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* @defgroup int13types INT 13 disk types
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* @{
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*/
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/** No such drive */
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#define INT13_DISK_TYPE_NONE 0x00
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/** Floppy without change-line support */
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#define INT13_DISK_TYPE_FDD 0x01
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/** Floppy with change-line support */
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#define INT13_DISK_TYPE_FDD_CL 0x02
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/** Hard disk */
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#define INT13_DISK_TYPE_HDD 0x03
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/** @} */
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/**
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* @defgroup int13flags INT 13 disk parameter flags
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* @{
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*/
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/** DMA boundary errors handled transparently */
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#define INT13_FL_DMA_TRANSPARENT 0x01
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/** CHS information is valid */
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#define INT13_FL_CHS_VALID 0x02
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/** Removable drive */
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#define INT13_FL_REMOVABLE 0x04
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/** Write with verify supported */
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#define INT13_FL_VERIFIABLE 0x08
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/** Has change-line supported (valid only for removable drives) */
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#define INT13_FL_CHANGE_LINE 0x10
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/** Drive can be locked (valid only for removable drives) */
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#define INT13_FL_LOCKABLE 0x20
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/** CHS is max possible, not current media (valid only for removable drives) */
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#define INT13_FL_CHS_MAX 0x40
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/** @} */
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/**
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* @defgroup int13exts INT 13 extension flags
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* @{
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*/
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/** Extended disk access functions supported */
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#define INT13_EXTENSION_LINEAR 0x01
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/** Removable drive functions supported */
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#define INT13_EXTENSION_REMOVABLE 0x02
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/** EDD functions supported */
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#define INT13_EXTENSION_EDD 0x04
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/** @} */
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/**
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* @defgroup int13vers INT 13 extension versions
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* @{
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*/
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/** INT13 extensions version 1.x */
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#define INT13_EXTENSION_VER_1_X 0x01
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/** INT13 extensions version 2.0 (EDD-1.0) */
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#define INT13_EXTENSION_VER_2_0 0x20
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/** INT13 extensions version 2.1 (EDD-1.1) */
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#define INT13_EXTENSION_VER_2_1 0x21
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/** INT13 extensions version 3.0 (EDD-3.0) */
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#define INT13_EXTENSION_VER_3_0 0x30
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/** @} */
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/** Bootable CD-ROM specification packet */
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struct int13_cdrom_specification {
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/** Size of packet in bytes */
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uint8_t size;
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/** Boot media type */
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uint8_t media_type;
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/** Drive number */
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uint8_t drive;
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/** CD-ROM controller number */
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uint8_t controller;
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/** LBA of disk image to emulate */
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uint32_t lba;
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/** Device specification */
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uint16_t device;
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/** Segment of 3K buffer for caching CD-ROM reads */
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uint16_t cache_segment;
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/** Load segment for initial boot image */
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uint16_t load_segment;
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/** Number of 512-byte sectors to load */
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uint16_t load_sectors;
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/** Low 8 bits of cylinder number */
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uint8_t cyl;
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/** Sector number, plus high 2 bits of cylinder number */
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uint8_t cyl_sector;
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/** Head number */
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uint8_t head;
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} __attribute__ (( packed ));
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/** A C/H/S address within a partition table entry */
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struct partition_chs {
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/** Head number */
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uint8_t head;
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/** Sector number, plus high 2 bits of cylinder number */
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uint8_t cyl_sector;
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/** Low 8 bits of cylinder number */
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uint8_t cyl;
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} __attribute__ (( packed ));
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#define PART_HEAD(chs) ( (chs).head )
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#define PART_SECTOR(chs) ( (chs).cyl_sector & 0x3f )
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#define PART_CYLINDER(chs) ( (chs).cyl | ( ( (chs).cyl_sector & 0xc0 ) << 2 ) )
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/** A partition table entry within the MBR */
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struct partition_table_entry {
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/** Bootable flag */
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uint8_t bootable;
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/** C/H/S start address */
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struct partition_chs chs_start;
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/** System indicator (partition type) */
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uint8_t type;
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/** C/H/S end address */
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struct partition_chs chs_end;
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/** Linear start address */
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uint32_t start;
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/** Linear length */
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uint32_t length;
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} __attribute__ (( packed ));
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/** A Master Boot Record */
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struct master_boot_record {
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uint8_t pad[446];
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/** Partition table */
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struct partition_table_entry partitions[4];
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/** 0x55aa MBR signature */
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uint16_t signature;
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} __attribute__ (( packed ));
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extern void register_int13_drive ( struct int13_drive *drive );
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extern void unregister_int13_drive ( struct int13_drive *drive );
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extern int int13_boot ( unsigned int drive );
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#endif /* INT13_H */
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