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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 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_int13_extensions (int ah, int drive, void *dap);
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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 check_int13_extensions (int drive);
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extern int get_diskinfo_int13_extensions (int drive, void *drp);
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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 int get_diskinfo_floppy (int drive,
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unsigned long *cylinders,
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unsigned long *sectors);
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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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if (geometry->flags & BIOSDISK_FLAG_LBA_EXTENSION)
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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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/* XXX: Don't check the geometry by default, because some buggy
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BIOSes don't return the number of total sectors correctly,
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even if they have working LBA support. Hell. */
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#ifdef NO_BUGGY_BIOS_IN_THE_WORLD
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if (sector >= geometry->total_sectors)
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return BIOSDISK_ERROR_GEOMETRY;
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#endif /* NO_BUGGY_BIOS_IN_THE_WORLD */
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/* FIXME: sizeof (DAP) must be 0x10. Should assert that the compiler
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can't add any padding. */
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dap.length = sizeof (dap);
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/* This is undocumented part. The address is formated in
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dap.buffer = segment << 16;
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err = biosdisk_int13_extensions (read + 0x42, drive, &dap);
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/* #undef NO_INT13_FALLBACK */
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#ifndef NO_INT13_FALLBACK
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geometry->flags &= ~BIOSDISK_FLAG_LBA_EXTENSION;
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geometry->total_sectors = (geometry->cylinders
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return biosdisk (read, drive, geometry, sector, nsec, segment);
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#endif /* ! NO_INT13_FALLBACK */
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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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if (cylinder_offset >= geometry->cylinders)
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return BIOSDISK_ERROR_GEOMETRY;
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err = biosdisk_standard (read + 0x02, drive,
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cylinder_offset, head_offset, sector_offset,
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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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/* Clear the flags. */
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unsigned long total_sectors = 0;
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version = check_int13_extensions (drive);
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struct drive_parameters
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unsigned short flags;
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unsigned long cylinders;
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unsigned long sectors;
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unsigned long long total_sectors;
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unsigned short bytes_per_sector;
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/* ver 2.0 or higher */
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unsigned long EDD_configuration_parameters;
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/* ver 3.0 or higher */
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unsigned short signature_dpi;
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unsigned char length_dpi;
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unsigned char reserved[3];
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unsigned char name_of_host_bus[4];
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unsigned char name_of_interface_type[8];
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unsigned char interface_path[8];
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unsigned char device_path[8];
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unsigned char reserved2;
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unsigned char checksum;
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/* XXX: This is necessary, because the BIOS of Thinkpad X20
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writes a garbage to the tail of drive parameters,
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regardless of a size specified in a caller. */
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unsigned char dummy[16];
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} __attribute__ ((packed)) drp;
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/* It is safe to clear out DRP. */
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grub_memset (&drp, 0, sizeof (drp));
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drp.size = sizeof (drp);
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err = get_diskinfo_int13_extensions (drive, &drp);
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/* Set the LBA flag. */
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geometry->flags = BIOSDISK_FLAG_LBA_EXTENSION;
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/* I'm not sure if GRUB should check the bit 1 of DRP.FLAGS,
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so I omit the check for now. - okuji */
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/* if (drp.flags & (1 << 1)) */
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/* FIXME: when the 2TB limit becomes critical, we must
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change the type of TOTAL_SECTORS to unsigned long
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if (drp.total_sectors)
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total_sectors = drp.total_sectors & ~0L;
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/* Some buggy BIOSes doesn't return the total sectors
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correctly but returns zero. So if it is zero, compute
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it by C/H/S returned by the LBA BIOS call. */
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total_sectors = drp.cylinders * drp.heads * drp.sectors;
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/* Don't pass GEOMETRY directly, but pass each element instead,
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so that we can change the structure easily. */
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err = get_diskinfo_standard (drive,
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&geometry->cylinders,
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total_sectors = (geometry->cylinders
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* geometry->sectors);
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geometry->total_sectors = total_sectors;
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/* First, try INT 13 AH=8h call. */
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err = get_diskinfo_standard (drive,
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&geometry->cylinders,
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/* If fails, then try floppy-specific probe routine. */
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err = get_diskinfo_floppy (drive,
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&geometry->cylinders,
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geometry->total_sectors = (geometry->cylinders
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* geometry->sectors);
added
removed
stage2/bios.c
