aboutsummaryrefslogtreecommitdiff
path: root/hw/hd-geometry.c
blob: c30514364f162262ef5a19b31b47e66b0bb34595 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
/*
 * 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 "block/block.h"
#include "hw/block-common.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(BlockDriverState *bs,
                           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;

    bdrv_get_geometry(bs, &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 (bdrv_read_unthrottled(bs, 0, buf, 1) < 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(bs, cylinders, heads, sectors);
            return 0;
        }
    }
    return -1;
}

static void guess_chs_for_size(BlockDriverState *bs,
                uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs)
{
    uint64_t nb_sectors;
    int cylinders;

    bdrv_get_geometry(bs, &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(BlockDriverState *bs,
                       uint32_t *pcyls, uint32_t *pheads, uint32_t *psecs,
                       int *ptrans)
{
    int cylinders, heads, secs, translation;

    if (guess_disk_lchs(bs, &cylinders, &heads, &secs) < 0) {
        /* no LCHS guess: use a standard physical disk geometry  */
        guess_chs_for_size(bs, 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(bs, 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(bs, *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;
}