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1 | /* |
2 | * Hard disk geometry utilities | |
3 | * | |
4 | * Copyright (C) 2012 Red Hat, Inc. | |
5 | * | |
6 | * This work is licensed under the terms of the GNU GPL, version 2 or later. | |
7 | * See the COPYING file in the top-level directory. | |
8 | * | |
9 | * This file incorporates work covered by the following copyright and | |
10 | * permission notice: | |
11 | * | |
12 | * Copyright (c) 2003 Fabrice Bellard | |
13 | * | |
14 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
15 | * of this software and associated documentation files (the "Software"), to deal | |
16 | * in the Software without restriction, including without limitation the rights | |
17 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
18 | * copies of the Software, and to permit persons to whom the Software is | |
19 | * furnished to do so, subject to the following conditions: | |
20 | * | |
21 | * The above copyright notice and this permission notice shall be included in | |
22 | * all copies or substantial portions of the Software. | |
23 | * | |
24 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
25 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
26 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL | |
27 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
28 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
29 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN | |
30 | * THE SOFTWARE. | |
31 | */ | |
32 | ||
33 | #include "block.h" | |
34 | #include "hw/block-common.h" | |
35 | ||
36 | struct partition { | |
37 | uint8_t boot_ind; /* 0x80 - active */ | |
38 | uint8_t head; /* starting head */ | |
39 | uint8_t sector; /* starting sector */ | |
40 | uint8_t cyl; /* starting cylinder */ | |
41 | uint8_t sys_ind; /* What partition type */ | |
42 | uint8_t end_head; /* end head */ | |
43 | uint8_t end_sector; /* end sector */ | |
44 | uint8_t end_cyl; /* end cylinder */ | |
45 | uint32_t start_sect; /* starting sector counting from 0 */ | |
46 | uint32_t nr_sects; /* nr of sectors in partition */ | |
47 | } QEMU_PACKED; | |
48 | ||
49 | /* try to guess the disk logical geometry from the MSDOS partition table. | |
50 | Return 0 if OK, -1 if could not guess */ | |
51 | static int guess_disk_lchs(BlockDriverState *bs, | |
52 | int *pcylinders, int *pheads, int *psectors) | |
53 | { | |
54 | uint8_t buf[BDRV_SECTOR_SIZE]; | |
55 | int i, heads, sectors, cylinders; | |
56 | struct partition *p; | |
57 | uint32_t nr_sects; | |
58 | uint64_t nb_sectors; | |
59 | ||
60 | bdrv_get_geometry(bs, &nb_sectors); | |
61 | ||
62 | /** | |
63 | * The function will be invoked during startup not only in sync I/O mode, | |
64 | * but also in async I/O mode. So the I/O throttling function has to | |
65 | * be disabled temporarily here, not permanently. | |
66 | */ | |
67 | if (bdrv_read_unthrottled(bs, 0, buf, 1) < 0) { | |
68 | return -1; | |
69 | } | |
70 | /* test msdos magic */ | |
71 | if (buf[510] != 0x55 || buf[511] != 0xaa) { | |
72 | return -1; | |
73 | } | |
74 | for (i = 0; i < 4; i++) { | |
75 | p = ((struct partition *)(buf + 0x1be)) + i; | |
76 | nr_sects = le32_to_cpu(p->nr_sects); | |
77 | if (nr_sects && p->end_head) { | |
78 | /* We make the assumption that the partition terminates on | |
79 | a cylinder boundary */ | |
80 | heads = p->end_head + 1; | |
81 | sectors = p->end_sector & 63; | |
82 | if (sectors == 0) { | |
83 | continue; | |
84 | } | |
85 | cylinders = nb_sectors / (heads * sectors); | |
86 | if (cylinders < 1 || cylinders > 16383) { | |
87 | continue; | |
88 | } | |
89 | *pheads = heads; | |
90 | *psectors = sectors; | |
91 | *pcylinders = cylinders; | |
92 | #if 0 | |
93 | printf("guessed geometry: LCHS=%d %d %d\n", | |
94 | cylinders, heads, sectors); | |
95 | #endif | |
96 | return 0; | |
97 | } | |
98 | } | |
99 | return -1; | |
100 | } | |
101 | ||
102 | void hd_geometry_guess(BlockDriverState *bs, | |
103 | int *pcyls, int *pheads, int *psecs) | |
104 | { | |
105 | int translation, lba_detected = 0; | |
106 | int cylinders, heads, secs; | |
107 | uint64_t nb_sectors; | |
108 | ||
109 | /* if a geometry hint is available, use it */ | |
110 | bdrv_get_geometry(bs, &nb_sectors); | |
111 | bdrv_get_geometry_hint(bs, &cylinders, &heads, &secs); | |
112 | translation = bdrv_get_translation_hint(bs); | |
113 | if (cylinders != 0) { | |
114 | *pcyls = cylinders; | |
115 | *pheads = heads; | |
116 | *psecs = secs; | |
117 | } else { | |
118 | if (guess_disk_lchs(bs, &cylinders, &heads, &secs) == 0) { | |
119 | if (heads > 16) { | |
120 | /* if heads > 16, it means that a BIOS LBA | |
121 | translation was active, so the default | |
122 | hardware geometry is OK */ | |
123 | lba_detected = 1; | |
124 | goto default_geometry; | |
125 | } else { | |
126 | *pcyls = cylinders; | |
127 | *pheads = heads; | |
128 | *psecs = secs; | |
129 | /* disable any translation to be in sync with | |
130 | the logical geometry */ | |
131 | if (translation == BIOS_ATA_TRANSLATION_AUTO) { | |
132 | bdrv_set_translation_hint(bs, | |
133 | BIOS_ATA_TRANSLATION_NONE); | |
134 | } | |
135 | } | |
136 | } else { | |
137 | default_geometry: | |
138 | /* if no geometry, use a standard physical disk geometry */ | |
139 | cylinders = nb_sectors / (16 * 63); | |
140 | ||
141 | if (cylinders > 16383) { | |
142 | cylinders = 16383; | |
143 | } else if (cylinders < 2) { | |
144 | cylinders = 2; | |
145 | } | |
146 | *pcyls = cylinders; | |
147 | *pheads = 16; | |
148 | *psecs = 63; | |
149 | if ((lba_detected == 1) | |
150 | && (translation == BIOS_ATA_TRANSLATION_AUTO)) { | |
151 | if ((*pcyls * *pheads) <= 131072) { | |
152 | bdrv_set_translation_hint(bs, | |
153 | BIOS_ATA_TRANSLATION_LARGE); | |
154 | } else { | |
155 | bdrv_set_translation_hint(bs, | |
156 | BIOS_ATA_TRANSLATION_LBA); | |
157 | } | |
158 | } | |
159 | } | |
160 | bdrv_set_geometry_hint(bs, *pcyls, *pheads, *psecs); | |
161 | } | |
162 | } |