1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2009 Pierre-Alexandre Meyer
4 *
5 * Some parts borrowed from chain.c32:
6 *
7 * Copyright 2003-2009 H. Peter Anvin - All Rights Reserved
8 * Copyright 2009 Intel Corporation; author: H. Peter Anvin
9 *
10 * This file is part of Syslinux, and is made available under
11 * the terms of the GNU General Public License version 2.
12 *
13 * ----------------------------------------------------------------------- */
14
15 #include <com32.h>
16 #include <string.h>
17 #include <stdio.h>
18 #include <disk/geom.h>
19
20 #include <stdio.h>
21
22 /**
23 * lba_to_chs - split given lba into cylinders/heads/sectors
24 **/
lba_to_chs(const struct driveinfo * drive_info,const int lba,unsigned int * cylinder,unsigned int * head,unsigned int * sector)25 void lba_to_chs(const struct driveinfo *drive_info, const int lba,
26 unsigned int *cylinder, unsigned int *head,
27 unsigned int *sector)
28 {
29 unsigned int track;
30
31 /* Use EDD, if valid */
32 if (drive_info->edd_params.sectors_per_track > 0 &&
33 drive_info->edd_params.heads > 0) {
34 *cylinder = (lba % drive_info->edd_params.sectors_per_track) + 1;
35 track = lba / drive_info->edd_params.sectors_per_track;
36 *head = track % drive_info->edd_params.heads;
37 *sector = track / drive_info->edd_params.heads;
38 } else if (drive_info->cbios) {
39 *cylinder = (lba % drive_info->legacy_sectors_per_track) + 1;
40 track = lba / drive_info->legacy_sectors_per_track;
41 *head = track % (drive_info->legacy_max_head + 1);
42 *sector = track / (drive_info->legacy_max_head + 1);
43 }
44 }
45
46 /**
47 * detect_extensions - detect if we can use extensions
48 *
49 * INT 13 - IBM/MS INT 13 Extensions - INSTALLATION CHECK
50 * AH = 41h
51 * BX = 55AAh
52 * DL = drive (80h-FFh)
53 *
54 * Return: CF set on error (extensions not supported)
55 * AH = 01h (invalid function)
56 * CF clear if successful
57 * BX = AA55h if installed
58 * AH = major version of extensions
59 * 01h = 1.x
60 * 20h = 2.0 / EDD-1.0
61 * 21h = 2.1 / EDD-1.1
62 * 30h = EDD-3.0
63 * AL = internal use
64 * CX = API subset support bitmap (see #00271)
65 * DH = extension version (v2.0+ ??? -- not present in 1.x)
66 *
67 * Note: the Phoenix Enhanced Disk Drive Specification v1.0 uses version 2.0 of
68 * the INT 13 Extensions API
69 *
70 * Bitfields for IBM/MS INT 13 Extensions API support bitmap:
71 * Bit(s) Description (Table 00271)
72 * 0 extended disk access functions (AH=42h-44h,47h,48h) supported
73 * 1 removable drive controller functions (AH=45h,46h,48h,49h,INT 15/AH=52h)
74 * supported
75 * 2 enhanced disk drive (EDD) functions (AH=48h,AH=4Eh) supported
76 * extended drive parameter table is valid (see #00273,#00278)
77 * 3-15 reserved (0)
78 **/
detect_extensions(struct driveinfo * drive_info)79 static int detect_extensions(struct driveinfo *drive_info)
80 {
81 com32sys_t getebios, ebios;
82
83 memset(&getebios, 0, sizeof getebios);
84 memset(&ebios, 0, sizeof ebios);
85
86 getebios.eflags.b[0] = 0x3; /* CF set */
87 getebios.ebx.w[0] = 0x55aa;
88 getebios.edx.b[0] = drive_info->disk;
89 getebios.eax.b[1] = 0x41;
90
91 __intcall(0x13, &getebios, &ebios);
92
93 if (!(ebios.eflags.l & EFLAGS_CF) && ebios.ebx.w[0] == 0xaa55) {
94 drive_info->ebios = 1;
95 drive_info->edd_version = ebios.eax.b[1];
96 drive_info->edd_functionality_subset = ebios.ecx.w[0];
97 return 0;
98 } else
99 return -1; /* Drive does not exist? */
100 }
101
102 /**
103 * get_drive_parameters_with_extensions - retrieve disk parameters via AH=48h
104 *
105 * INT 13 - IBM/MS INT 13 Extensions - GET DRIVE PARAMETERS
106 * AH = 48h
107 * DL = drive (80h-FFh)
108 * DS:SI -> buffer for drive parameters
109 * Return: CF clear if successful
110 * AH = 00h
111 * DS:SI buffer filled
112 * CF set on error
113 * AH = error code (see #00234)
114 * BUG: several different Compaq BIOSes incorrectly report high-numbered
115 * drives (such as 90h, B0h, D0h, and F0h) as present, giving them the
116 * same geometry as drive 80h; as a workaround, scan through disk
117 * numbers, stopping as soon as the number of valid drives encountered
118 * equals the value in 0040h:0075h
119 **/
get_drive_parameters_with_extensions(struct driveinfo * drive_info)120 static int get_drive_parameters_with_extensions(struct driveinfo *drive_info)
121 {
122 com32sys_t inreg, outreg;
123 struct edd_device_parameters *dp;
124
125 memset(&inreg, 0, sizeof inreg);
126
127 /*
128 * The caller shall set this value to the maximum Result Buffer
129 * length, in bytes. If the length of this buffer is less than 30
130 * bytes, this function shall not return the pointer to Drive Parameter
131 * Table (DPT) extension. If the buffer length is 30 or greater on
132 * entry, it shall be set to 30 on exit. If the buffer length is
133 * between 26 and 29, it shall be set to 26 on exit.
134 * If the buffer length is less than 26 on entry an error shall be
135 * returned.
136 */
137 dp = lmalloc(sizeof *dp);
138 if (!dp)
139 return -1;
140
141 dp->len = sizeof(struct edd_device_parameters);
142
143 inreg.esi.w[0] = OFFS(dp);
144 inreg.ds = SEG(dp);
145 inreg.edx.b[0] = drive_info->disk;
146 inreg.eax.b[1] = 0x48;
147
148 __intcall(0x13, &inreg, &outreg);
149
150 /* CF set on error */
151 if (outreg.eflags.l & EFLAGS_CF) {
152 lfree(dp);
153 return outreg.eax.b[1];
154 }
155
156 memcpy(&drive_info->edd_params, dp, sizeof drive_info->edd_params);
157 lfree(dp);
158
159 return 0;
160 }
161
162 /**
163 * get_drive_parameters_without_extensions - retrieve drive parameters via AH=08h
164 *
165 * INT 13 - DISK - GET DRIVE PARAMETERS (PC,XT286,CONV,PS,ESDI,SCSI)
166 * AH = 08h
167 * DL = drive (bit 7 set for hard disk)
168 *
169 * Return: CF set on error
170 * AH = status (07h) (see #00234)
171 * CF clear if successful
172 * AH = 00h
173 * AL = 00h on at least some BIOSes
174 * BL = drive type (AT/PS2 floppies only) (see #00242)
175 * CH = low eight bits of maximum cylinder number
176 * CL = maximum sector number (bits 5-0)
177 * high two bits of maximum cylinder number (bits 7-6)
178 * DH = maximum head number
179 * DL = number of drives
180 * ES:DI -> drive parameter table (floppies only)
181 *
182 * Notes:
183 * - may return successful even though specified drive is greater than the
184 * number of attached drives of that type (floppy/hard); check DL to
185 * ensure validity
186 * - for systems predating the IBM AT, this call is only valid for hard
187 * disks, as it is implemented by the hard disk BIOS rather than the
188 * ROM BIOS
189 * - Toshiba laptops with HardRAM return DL=02h when called with DL=80h,
190 * but fail on DL=81h. The BIOS data at 40h:75h correctly reports 01h.
191 * may indicate only two drives present even if more are attached; to
192 * ensure a correct count, one can use AH=15h to scan through possible
193 * drives
194 * - for BIOSes which reserve the last cylinder for testing purposes, the
195 * cylinder count is automatically decremented
196 * on PS/1s with IBM ROM DOS 4, nonexistent drives return CF clear,
197 * BX=CX=0000h, and ES:DI = 0000h:0000h
198 * - the PC-Tools PCFORMAT program requires that AL=00h before it will
199 * proceed with the formatting
200 *
201 * BUG: several different Compaq BIOSes incorrectly report high-numbered
202 * drives (such as 90h, B0h, D0h, and F0h) as present, giving them the
203 * same geometry as drive 80h; as a workaround, scan through disk
204 * numbers, stopping as soon as the number of valid drives encountered
205 * equals the value in 0040h:0075h
206 *
207 * SeeAlso: AH=06h"Adaptec",AH=13h"SyQuest",AH=48h,AH=15h,INT 1E
208 * SeeAlso: INT 41"HARD DISK 0"
209 **/
get_drive_parameters_without_extensions(struct driveinfo * drive_info)210 static int get_drive_parameters_without_extensions(struct driveinfo *drive_info)
211 {
212 com32sys_t getparm, parm;
213
214 memset(&getparm, 0, sizeof getparm);
215 memset(&parm, 0, sizeof parm);
216
217 /* Ralf Brown recommends setting ES:DI to 0:0 */
218 getparm.esi.w[0] = 0;
219 getparm.ds = 0;
220 getparm.edx.b[0] = drive_info->disk;
221 getparm.eax.b[1] = 0x08;
222
223 __intcall(0x13, &getparm, &parm);
224
225 /* CF set on error */
226 if (parm.eflags.l & EFLAGS_CF)
227 return parm.eax.b[1];
228
229 /* DL contains the maximum drive number (it starts at 0) */
230 drive_info->legacy_max_drive = parm.edx.b[0];
231
232 // XXX broken
233 /* Drive specified greater than the bumber of attached drives */
234 //if (drive_info->disk > drive_info->drives)
235 // return -1;
236
237 drive_info->legacy_type = parm.ebx.b[0];
238
239 /* DH contains the maximum head number (it starts at 0) */
240 drive_info->legacy_max_head = parm.edx.b[1];
241
242 /* Maximum sector number (bits 5-0) per track */
243 drive_info->legacy_sectors_per_track = parm.ecx.b[0] & 0x3f;
244
245 /*
246 * Maximum cylinder number:
247 * CH = low eight bits of maximum cylinder number
248 * CL = high two bits of maximum cylinder number (bits 7-6)
249 */
250 drive_info->legacy_max_cylinder = parm.ecx.b[1] +
251 ((parm.ecx.b[0] & 0xc0) << 2);
252
253 if (drive_info->legacy_sectors_per_track > 0)
254 drive_info->cbios = 1; /* Valid geometry */
255
256 return 0;
257 }
258
259 /**
260 * get_drive_parameters - retrieve drive parameters
261 * @drive_info: driveinfo structure to fill
262 **/
get_drive_parameters(struct driveinfo * drive_info)263 int get_drive_parameters(struct driveinfo *drive_info)
264 {
265 int return_code;
266
267 if (detect_extensions(drive_info))
268 return -1;
269
270 return_code = get_drive_parameters_without_extensions(drive_info);
271
272 /* If geometry isn't valid, no need to try to get more info about the drive */
273 /* Looks like in can confuse some optical drives */
274 if (drive_info->ebios && drive_info->cbios)
275 get_drive_parameters_with_extensions(drive_info);
276
277 return return_code;
278 }
279