164 lines
5.7 KiB
C
164 lines
5.7 KiB
C
/*
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* Hard disk geometry utilities
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*
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* Copyright (C) 2012 Red Hat, Inc.
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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* This file incorporates work covered by the following copyright and
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* permission notice:
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu/osdep.h"
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#include "sysemu/block-backend.h"
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#include "qapi/qapi-types-block.h"
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#include "qemu/bswap.h"
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#include "hw/block/block.h"
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#include "trace.h"
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struct partition {
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uint8_t boot_ind; /* 0x80 - active */
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uint8_t head; /* starting head */
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uint8_t sector; /* starting sector */
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uint8_t cyl; /* starting cylinder */
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uint8_t sys_ind; /* What partition type */
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uint8_t end_head; /* end head */
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uint8_t end_sector; /* end sector */
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uint8_t end_cyl; /* end cylinder */
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uint32_t start_sect; /* starting sector counting from 0 */
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uint32_t nr_sects; /* nr of sectors in partition */
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} QEMU_PACKED;
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/* try to guess the disk logical geometry from the MSDOS partition table.
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Return 0 if OK, -1 if could not guess */
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static int guess_disk_lchs(BlockBackend *blk,
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int *pcylinders, int *pheads, int *psectors)
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{
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uint8_t buf[BDRV_SECTOR_SIZE];
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int i, heads, sectors, cylinders;
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struct partition *p;
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uint32_t nr_sects;
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uint64_t nb_sectors;
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blk_get_geometry(blk, &nb_sectors);
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if (blk_pread(blk, 0, buf, BDRV_SECTOR_SIZE) < 0) {
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return -1;
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}
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/* test msdos magic */
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if (buf[510] != 0x55 || buf[511] != 0xaa) {
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return -1;
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}
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for (i = 0; i < 4; i++) {
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p = ((struct partition *)(buf + 0x1be)) + i;
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nr_sects = le32_to_cpu(p->nr_sects);
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if (nr_sects && p->end_head) {
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/* We make the assumption that the partition terminates on
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a cylinder boundary */
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heads = p->end_head + 1;
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sectors = p->end_sector & 63;
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if (sectors == 0) {
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continue;
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}
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cylinders = nb_sectors / (heads * sectors);
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if (cylinders < 1 || cylinders > 16383) {
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continue;
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}
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*pheads = heads;
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*psectors = sectors;
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*pcylinders = cylinders;
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trace_hd_geometry_lchs_guess(blk, cylinders, heads, sectors);
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return 0;
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}
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}
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return -1;
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}
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static void guess_chs_for_size(BlockBackend *blk,
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uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs)
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{
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uint64_t nb_sectors;
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int cylinders;
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blk_get_geometry(blk, &nb_sectors);
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cylinders = nb_sectors / (16 * 63);
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if (cylinders > 16383) {
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cylinders = 16383;
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} else if (cylinders < 2) {
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cylinders = 2;
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}
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*pcyls = cylinders;
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*pheads = 16;
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*psecs = 63;
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}
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void hd_geometry_guess(BlockBackend *blk,
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uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs,
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int *ptrans)
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{
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int cylinders, heads, secs, translation;
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HDGeometry geo;
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/* Try to probe the backing device geometry, otherwise fallback
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to the old logic. (as of 12/2014 probing only succeeds on DASDs) */
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if (blk_probe_geometry(blk, &geo) == 0) {
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*pcyls = geo.cylinders;
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*psecs = geo.sectors;
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*pheads = geo.heads;
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translation = BIOS_ATA_TRANSLATION_NONE;
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} else if (guess_disk_lchs(blk, &cylinders, &heads, &secs) < 0) {
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/* no LCHS guess: use a standard physical disk geometry */
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guess_chs_for_size(blk, pcyls, pheads, psecs);
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translation = hd_bios_chs_auto_trans(*pcyls, *pheads, *psecs);
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} else if (heads > 16) {
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/* LCHS guess with heads > 16 means that a BIOS LBA
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translation was active, so a standard physical disk
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geometry is OK */
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guess_chs_for_size(blk, pcyls, pheads, psecs);
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translation = *pcyls * *pheads <= 131072
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? BIOS_ATA_TRANSLATION_LARGE
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: BIOS_ATA_TRANSLATION_LBA;
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} else {
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/* LCHS guess with heads <= 16: use as physical geometry */
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*pcyls = cylinders;
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*pheads = heads;
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*psecs = secs;
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/* disable any translation to be in sync with
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the logical geometry */
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translation = BIOS_ATA_TRANSLATION_NONE;
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}
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if (ptrans) {
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*ptrans = translation;
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}
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trace_hd_geometry_guess(blk, *pcyls, *pheads, *psecs, translation);
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}
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int hd_bios_chs_auto_trans(uint32_t cyls, uint32_t heads, uint32_t secs)
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{
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return cyls <= 1024 && heads <= 16 && secs <= 63
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? BIOS_ATA_TRANSLATION_NONE
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: BIOS_ATA_TRANSLATION_LBA;
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}
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