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/* bios.c - implement C part of low-level BIOS disk input and output */
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 1999,2000,2003,2004 Free Software Foundation, Inc.
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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/* These are defined in asm.S, and never be used elsewhere, so declare the
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extern int biosdisk_standard (int ah, int drive,
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int coff, int hoff, int soff,
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int nsec, int segment);
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extern int get_diskinfo_standard (int drive,
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unsigned long *cylinders,
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unsigned long *sectors);
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extern struct drive_map_slot hooked_drive_map[DRIVE_MAP_SIZE + 1];
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extern int drive_map_slot_empty (struct drive_map_slot item);
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/* Read/write NSEC sectors starting from SECTOR in DRIVE disk with GEOMETRY
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from/into SEGMENT segment. If READ is BIOSDISK_READ, then read it,
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else if READ is BIOSDISK_WRITE, then write it. If an geometry error
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occurs, return BIOSDISK_ERROR_GEOMETRY, and if other error occurs, then
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return the error number. Otherwise, return 0. */
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biosdisk (int read, int drive, struct geometry *geometry,
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int sector, int nsec, int segment)
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/* first, use EBIOS if possible */
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if ((geometry->flags & BIOSDISK_FLAG_LBA_EXTENSION) && (! (geometry->flags & BIOSDISK_FLAG_BIFURCATE) || (drive & 0xFFFFFF00) == 0x100))
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struct disk_address_packet
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unsigned char reserved;
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unsigned short blocks;
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unsigned long long block;
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/* This structure is passed in the stack. A buggy BIOS could write
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* garbage data to the tail of the struct and hang the machine. So
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* we need this protection. - Tinybit
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unsigned char dummy[16];
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} __attribute__ ((packed)) *dap;
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/* Even the above protection is not enough to avoid stupid actions by
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* buggy BIOSes. So we do it in the 0040:0000 segment. - Tinybit
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dap = (struct disk_address_packet *)0x580;
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if (drive == 0xffff || (drive == ram_drive && rd_base != 0xffffffff))
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if (nsec <=0 || nsec >= 0x80)
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return 1; /* failure */
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disk_sector = (char *)((sector<<9) + ((drive==0xffff) ? 0 : rd_base));
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buf_address = (char *)(segment<<4);
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if (read) /* read == 1 really means write to DISK */
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grub_memmove (disk_sector, buf_address, nsec << 9);
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else /* read == 0 really means read from DISK */
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grub_memmove (buf_address, disk_sector, nsec << 9);
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return 0; /* success */
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dap->buffer = segment << 16;
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err = biosdisk_int13_extensions ((read + 0x42) << 8, (unsigned char)drive, dap);
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return 0; /* success */
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/* bootable CD-ROM specification has no standard CHS-mode call */
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if (geometry->flags & BIOSDISK_FLAG_CDROM)
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grub_printf ("biosdisk_int13_extensions read=%d, drive=0x%x, dap=%x, err=0x%x\n", read, drive, dap, err);
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if (geometry->flags & BIOSDISK_FLAG_BIFURCATE)
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} /* if (geometry->flags & BIOSDISK_FLAG_LBA_EXTENSION) */
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/* try the standard CHS mode */
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int cylinder_offset, head_offset, sector_offset;
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/* SECTOR_OFFSET is counted from one, while HEAD_OFFSET and
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CYLINDER_OFFSET are counted from zero. */
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sector_offset = sector % geometry->sectors + 1;
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head = sector / geometry->sectors;
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head_offset = head % geometry->heads;
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cylinder_offset = head / geometry->heads;
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err = biosdisk_standard (read + 0x02, drive,
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cylinder_offset, head_offset, sector_offset,
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/* Check bootable CD-ROM emulation status. Return 0 on failure. */
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get_cdinfo (int drive, struct geometry *geometry)
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struct iso_spec_packet
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unsigned char media_type;
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unsigned char drive_no;
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unsigned char controller_no;
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unsigned long image_lba;
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unsigned short device_spec;
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unsigned short cache_seg;
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unsigned short load_seg;
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unsigned short length_sec512;
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unsigned char cylinders;
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unsigned char sectors;
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unsigned char dummy[16];
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} __attribute__ ((packed));
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struct iso_spec_packet *cdrp;
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cdrp = (struct iso_spec_packet *)0x580;
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grub_memset (cdrp, 0, sizeof (struct iso_spec_packet));
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cdrp->size = sizeof (struct iso_spec_packet) - 16;
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grub_printf (" int13/4B01(%X),", drive);
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err = biosdisk_int13_extensions (0x4B01, drive, cdrp);
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grub_printf ("err=%X,drive=%X, ", err, drive);
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if (drive == 0x7F && drive < (unsigned long)(cdrp->drive_no))
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drive = cdrp->drive_no;
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if (! err && cdrp->drive_no == drive && !(cdrp->media_type & 0x0F))
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/* No-emulation mode bootable CD-ROM */
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geometry->flags = BIOSDISK_FLAG_LBA_EXTENSION | BIOSDISK_FLAG_CDROM;
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geometry->cylinders = 65536;
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geometry->heads = 255;
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geometry->sectors = 15;
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geometry->sector_size = 2048;
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geometry->total_sectors = 65536 * 255 * 15;
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return 0; /* failure */
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static unsigned long flags;
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static unsigned long cylinders;
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static unsigned long heads;
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static unsigned long sectors;
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/* Return the geometry of DRIVE in GEOMETRY. If an error occurs, return
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non-zero, otherwise zero. */
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get_diskinfo (int drive, struct geometry *geometry)
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unsigned long long total_sectors = 0, tmp = 0;
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if (drive == 0xffff) /* memory disk */
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unsigned long long total_mem_bytes;
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if (mbi.flags & MB_INFO_MEM_MAP)
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struct AddrRangeDesc *map = (struct AddrRangeDesc *) saved_mmap_addr;
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unsigned long end_addr = saved_mmap_addr + saved_mmap_length;
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for (; end_addr > (unsigned long) map; map = (struct AddrRangeDesc *) (((int) map) + 4 + map->size))
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unsigned long long top_end;
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if (map->Type != MB_ARD_MEMORY)
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top_end = map->BaseAddr + map->Length;
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if (top_end > 0x100000000ULL)
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top_end = 0x100000000ULL;
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if (total_mem_bytes < top_end)
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total_mem_bytes = top_end;
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grub_printf ("Address Map BIOS Interface is not activated.\n");
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geometry->flags = BIOSDISK_FLAG_LBA_EXTENSION;
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geometry->sector_size = SECTOR_SIZE;
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geometry->total_sectors = (total_mem_bytes /*+ SECTOR_SIZE - 1*/) >> SECTOR_BITS;
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geometry->heads = 255;
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geometry->sectors = 63;
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geometry->cylinders = (geometry->total_sectors + 255 * 63 -1) / (255 * 63);
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} else if (drive == ram_drive) /* ram disk device */
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if (rd_base != 0xffffffff)
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geometry->flags = BIOSDISK_FLAG_LBA_EXTENSION;
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geometry->sector_size = SECTOR_SIZE;
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geometry->total_sectors = (rd_size ? ((rd_size + SECTOR_SIZE - 1)>> SECTOR_BITS) : 0x800000);
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geometry->heads = 255;
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geometry->sectors = 63;
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geometry->cylinders = (geometry->total_sectors + 255 * 63 -1) / (255 * 63);
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#if defined(GRUB_UTIL) || defined(STAGE1_5)
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if (drive == cdrom_drive)
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if (drive == cdrom_drive || (drive >= (unsigned char)min_cdrom_id && drive < (unsigned char)(min_cdrom_id + atapi_dev_count)))
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/* No-emulation mode bootable CD-ROM */
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geometry->flags = BIOSDISK_FLAG_LBA_EXTENSION | BIOSDISK_FLAG_CDROM;
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geometry->cylinders = 65536;
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geometry->heads = 255;
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geometry->sectors = 15;
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geometry->sector_size = 2048;
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geometry->total_sectors = 65536 * 255 * 15;
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/* Clear the flags. */
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#define FIND_DRIVES 8
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#define FIND_DRIVES (*((char *)0x475))
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if (((unsigned char)drive) >= 0x80 + FIND_DRIVES /* || (version && (drive & 0x80)) */ )
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/* Possible CD-ROM - check the status. */
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if (get_cdinfo ((unsigned char)drive, geometry))
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#if (! defined(GRUB_UTIL)) && (! defined(STAGE1_5))
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/* check if the drive is virtual. */
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d = (unsigned char)drive;
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j = DRIVE_MAP_SIZE; /* real drive */
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if (! unset_int13_handler (1))
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for (j = 0; j < DRIVE_MAP_SIZE; j++)
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if (drive_map_slot_empty (hooked_drive_map[j]))
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j = DRIVE_MAP_SIZE; /* real drive */
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if (((unsigned char)drive) != hooked_drive_map[j].from_drive)
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if ((hooked_drive_map[j].max_sector & 0x3E) == 0 && hooked_drive_map[j].start_sector == 0 && hooked_drive_map[j].sector_count <= 1)
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/* this is a map for the whole drive. */
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d = hooked_drive_map[j].to_drive;
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j = DRIVE_MAP_SIZE; /* real drive */
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if (j == DRIVE_MAP_SIZE) /* real drive */
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if (d >= 0x80 && d < 0x84)
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if (hd_geom[d].sector_size == 512 && hd_geom[d].sectors > 0 && hd_geom[d].sectors <= 63 && hd_geom[d].heads <= 256)
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geometry->flags = hd_geom[d].flags;
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if ((geometry->flags & BIOSDISK_FLAG_BIFURCATE) && (drive & 0xFFFFFF00) == 0x100)
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if (geometry->flags & BIOSDISK_FLAG_CDROM)
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geometry->cylinders = 65536;
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geometry->heads = 255;
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geometry->sectors = 15;
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geometry->sector_size = 2048;
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geometry->total_sectors = 65536 * 255 * 15;
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geometry->sector_size = hd_geom[d].sector_size;
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geometry->total_sectors = hd_geom[d].total_sectors;
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geometry->heads = hd_geom[d].heads;
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geometry->sectors = hd_geom[d].sectors;
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geometry->cylinders = hd_geom[d].cylinders;
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if (fd_geom[d].sector_size == 512 && fd_geom[d].sectors > 0 && fd_geom[d].sectors <= 63 && fd_geom[d].heads <= 256)
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geometry->flags = fd_geom[d].flags;
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if ((geometry->flags & BIOSDISK_FLAG_BIFURCATE) && (drive & 0xFFFFFF00) == 0x100)
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if (geometry->flags & BIOSDISK_FLAG_CDROM)
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geometry->cylinders = 65536;
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geometry->heads = 255;
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geometry->sectors = 15;
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geometry->sector_size = 2048;
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geometry->total_sectors = 65536 * 255 * 15;
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geometry->sector_size = fd_geom[d].sector_size;
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geometry->total_sectors = fd_geom[d].total_sectors;
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geometry->heads = fd_geom[d].heads;
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geometry->sectors = fd_geom[d].sectors;
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geometry->cylinders = fd_geom[d].cylinders;
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grub_printf (" int13/41(%X),", drive);
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version = check_int13_extensions ((unsigned char)drive);
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grub_printf ("version=%X, ", version);
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/* Set the LBA flag. */
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if (version & 1) /* support functions 42h-44h, 47h-48h */
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flags = BIOSDISK_FLAG_LBA_EXTENSION;
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grub_printf (" int13/08(%X),", drive);
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version = get_diskinfo_standard ((unsigned char)drive, &cylinders, &heads, §ors);
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grub_printf ("version=%X, C/H/S=%d/%d/%d, ", version, cylinders, heads, sectors);
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grub_printf (" int13/02(%X),", drive);
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/* read the boot sector: int 13, AX=0x201, CX=1, DH=0 */
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err = biosdisk_standard (0x02, (unsigned char)drive, 0, 0, 1, 1, 0x5F00/*SCRATCHSEG*/);
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grub_printf ("err=%X, ", err);
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/* try again using LBA */
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if (flags & BIOSDISK_FLAG_LBA_EXTENSION || ((unsigned char)drive) >= 0x80 + FIND_DRIVES)
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struct disk_address_packet
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unsigned char length;
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unsigned char reserved;
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unsigned short blocks;
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unsigned long buffer;
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unsigned long long block;
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unsigned char dummy[16];
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} __attribute__ ((packed)) *dap;
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dap = (struct disk_address_packet *)0x580;
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dap->buffer = 0x5F80/*SCRATCHSEG*/ << 16;
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/* set a known value */
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grub_memset ((char *)0x5F800, 0xEC, 0x800);
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version = biosdisk_int13_extensions (0x4200, (unsigned char)drive, dap);
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/* see if it is a big sector */
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for (p = (char *)0x5FA00; p < (char *)0x60000; p++)
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if ((*p) != (char)0xEC)
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flags |= BIOSDISK_FLAG_CDROM | BIOSDISK_FLAG_LBA_EXTENSION;
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flags |= BIOSDISK_FLAG_BIFURCATE;
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if ((! version) && (! err))
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if (grub_memcmp ((char *)0x5F000, (char *)0x5F800, 0x200))
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flags |= BIOSDISK_FLAG_BIFURCATE;
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if (err && ! (flags & BIOSDISK_FLAG_BIFURCATE) && !(flags & BIOSDISK_FLAG_CDROM))
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grub_memmove ((char *)0x5F000, (char *)0x5F800, 0x200);
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} /* if (geometry->flags & BIOSDISK_FLAG_LBA_EXTENSION) */
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return err; /* When we return with ERROR, we should not change the geometry!! */
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geometry->flags = flags;
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if (err && (flags & BIOSDISK_FLAG_CDROM))
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geometry->cylinders = 65536;
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geometry->heads = 255;
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geometry->sectors = 15;
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geometry->sector_size = 2048;
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geometry->total_sectors = 65536 * 255 * 15;
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geometry->cylinders = cylinders;
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geometry->heads = heads;
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geometry->sectors = sectors;
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geometry->sector_size = SECTOR_SIZE;
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if (geometry->heads > 256)
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geometry->heads = 256;
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if (geometry->sectors * geometry->sector_size > 63 * 512)
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geometry->sectors = 63 * 512 / geometry->sector_size;
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tmp = (unsigned long long)(geometry->cylinders) *
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(unsigned long long)(geometry->heads) *
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(unsigned long long)(geometry->sectors);
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if (total_sectors < tmp)
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geometry->total_sectors = total_sectors;
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/* successfully read boot sector */
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if ((err = probe_mbr((struct master_and_dos_boot_sector *)0x5F000/*SCRATCHADDR*/, 0, total_sectors, 0)))
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grub_printf ("\nWarning: Unrecognized partition table for drive %X. Please rebuild it using\na Microsoft-compatible FDISK tool(err=%d). Current C/H/S=%d/%d/%d\n", drive, err, geometry->cylinders, geometry->heads, geometry->sectors);
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goto failure_probe_boot_sector;
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if (probe_bpb((struct master_and_dos_boot_sector *)0x5F000/*SCRATCHADDR*/))
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goto failure_probe_boot_sector;
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if (probed_cylinders != geometry->cylinders)
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grub_printf ("\nWarning: %s cylinders(%d) is not equal to the BIOS one(%d).\n", (char *)err, probed_cylinders, geometry->cylinders);
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geometry->cylinders = probed_cylinders;
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if (probed_heads != geometry->heads)
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grub_printf ("\nWarning: %s heads(%d) is not equal to the BIOS one(%d).\n", (char *)err, probed_heads, geometry->heads);
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geometry->heads = probed_heads;
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if (probed_sectors_per_track != geometry->sectors)
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grub_printf ("\nWarning: %s sectors per track(%d) is not equal to the BIOS one(%d).\n", (char *)err, probed_sectors_per_track, geometry->sectors);
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geometry->sectors = probed_sectors_per_track;
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if (probed_total_sectors > total_sectors)
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grub_printf ("\nWarning: %s total sectors(%d) is greater than the BIOS one(%d).\nSome buggy BIOSes could hang when you access sectors exceeding the BIOS limit.\n", (char *)err, probed_total_sectors, total_sectors);
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geometry->total_sectors = probed_total_sectors;
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if (probed_total_sectors < total_sectors)
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grub_printf ("\nWarning: %s total sectors(%d) is less than the BIOS one(%d).\n", (char *)err, probed_total_sectors, total_sectors);
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failure_probe_boot_sector:
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if (!(geometry->flags & BIOSDISK_FLAG_LBA_EXTENSION) && ! ((*(char *)0x8205) & 0x08))
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err = geometry->heads;
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version = geometry->sectors;
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/* DH non-zero for geometry_tune */
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get_diskinfo_standard (drive | 0x0100, &geometry->cylinders, &geometry->heads, &geometry->sectors);
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if (err != geometry->heads)
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grub_printf ("\nNotice: number of heads for drive %X tuned from %d to %d.\n", drive, err, geometry->heads);
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if (version != geometry->sectors)
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grub_printf ("\nNotice: sectors-per-track for drive %X tuned from %d to %d.\n", drive, version, geometry->sectors);
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/* if C/H/S=0/0/0, use a safe default one. */
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if (geometry->sectors == 0)
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geometry->sectors = 63;
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if (geometry->total_sectors > 5760)
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geometry->sectors = 63;
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else if (geometry->total_sectors > 2880)
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geometry->sectors = 36;
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geometry->sectors = 18;
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if (geometry->heads == 0)
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geometry->heads = 255;
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if (geometry->total_sectors > 5760)
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geometry->heads = 255;
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if (geometry->cylinders == 0)
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geometry->cylinders = (geometry->total_sectors / geometry->heads / geometry->sectors);
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if (geometry->cylinders == 0)
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geometry->cylinders = 1;
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#endif /* ! STAGE1_5 */
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/* backup the geometry into array hd_geom or fd_geom. */
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#if (! defined(GRUB_UTIL)) && (! defined(STAGE1_5))
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/* check if the drive is virtual. */
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d = (unsigned char)drive;
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j = DRIVE_MAP_SIZE; /* real drive */
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if (! unset_int13_handler (1))
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for (j = 0; j < DRIVE_MAP_SIZE; j++)
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if (drive_map_slot_empty (hooked_drive_map[j]))
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j = DRIVE_MAP_SIZE; /* real drive */
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if (((unsigned char)drive) != hooked_drive_map[j].from_drive)
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if ((hooked_drive_map[j].max_sector & 0x3E) == 0 && hooked_drive_map[j].start_sector == 0 && hooked_drive_map[j].sector_count <= 1)
643
/* this is a map for the whole drive. */
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d = hooked_drive_map[j].to_drive;
645
j = DRIVE_MAP_SIZE; /* real drive */
650
if (j == DRIVE_MAP_SIZE) /* real drive */
652
if (d >= 0x80 && d < 0x84)
655
if (hd_geom[d].sector_size != 512 || hd_geom[d].sectors <= 0 || hd_geom[d].sectors > 63 || hd_geom[d].heads > 256)
657
hd_geom[d].flags = geometry->flags;
658
hd_geom[d].sector_size = geometry->sector_size;
659
hd_geom[d].total_sectors = geometry->total_sectors;
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hd_geom[d].heads = geometry->heads;
661
hd_geom[d].sectors = geometry->sectors;
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hd_geom[d].cylinders = geometry->cylinders;
665
if (fd_geom[d].sector_size != 512 || fd_geom[d].sectors <= 0 || fd_geom[d].sectors > 63 || fd_geom[d].heads > 256)
667
fd_geom[d].flags = geometry->flags;
668
fd_geom[d].sector_size = geometry->sector_size;
669
fd_geom[d].total_sectors = geometry->total_sectors;
670
fd_geom[d].heads = geometry->heads;
671
fd_geom[d].sectors = geometry->sectors;
672
fd_geom[d].cylinders = geometry->cylinders;
677
if ((geometry->flags & BIOSDISK_FLAG_BIFURCATE) && (drive & 0xFFFFFF00) == 0x100)
679
if (geometry->flags & BIOSDISK_FLAG_CDROM)
681
geometry->cylinders = 65536;
682
geometry->heads = 255;
683
geometry->sectors = 15;
684
geometry->sector_size = 2048;
685
geometry->total_sectors = 65536 * 255 * 15;
added
removed
src/grub4dos/stage2/.svn/text-base/bios.c.svn-base
