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