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
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* Get EDD BIOS disk information
*/
#include "boot.h"
#include <linux/edd.h>
#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
/*
* Read the MBR (first sector) from a specific device.
*/
static int read_mbr(u8 devno, void *buf)
{
u16 ax, bx, cx, dx;
ax = 0x0201; /* Legacy Read, one sector */
cx = 0x0001; /* Sector 0-0-1 */
dx = devno;
bx = (size_t)buf;
asm volatile("pushfl; stc; int $0x13; setc %%al; popfl"
: "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx)
: : "esi", "edi", "memory");
return -(u8)ax; /* 0 or -1 */
}
static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
{
int sector_size;
char *mbrbuf_ptr, *mbrbuf_end;
u32 buf_base, mbr_base;
extern char _end[];
sector_size = ei->params.bytes_per_sector;
if (!sector_size)
sector_size = 512; /* Best available guess */
/* Produce a naturally aligned buffer on the heap */
buf_base = (ds() << 4) + (u32)&_end;
mbr_base = (buf_base+sector_size-1) & ~(sector_size-1);
mbrbuf_ptr = _end + (mbr_base-buf_base);
mbrbuf_end = mbrbuf_ptr + sector_size;
/* Make sure we actually have space on the heap... */
if (!(boot_params.hdr.loadflags & CAN_USE_HEAP))
return -1;
if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
return -1;
if (read_mbr(devno, mbrbuf_ptr))
return -1;
*mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
return 0;
}
static int get_edd_info(u8 devno, struct edd_info *ei)
{
u16 ax, bx, cx, dx, di;
memset(ei, 0, sizeof *ei);
/* Check Extensions Present */
ax = 0x4100;
bx = EDDMAGIC1;
dx = devno;
asm("pushfl; stc; int $0x13; setc %%al; popfl"
: "+a" (ax), "+b" (bx), "=c" (cx), "+d" (dx)
: : "esi", "edi");
if ((u8)ax)
return -1; /* No extended information */
if (bx != EDDMAGIC2)
return -1;
ei->device = devno;
ei->version = ax >> 8; /* EDD version number */
ei->interface_support = cx; /* EDD functionality subsets */
/* Extended Get Device Parameters */
ei->params.length = sizeof(ei->params);
ax = 0x4800;
dx = devno;
asm("pushfl; int $0x13; popfl"
: "+a" (ax), "+d" (dx), "=m" (ei->params)
: "S" (&ei->params)
: "ebx", "ecx", "edi");
/* Get legacy CHS parameters */
/* Ralf Brown recommends setting ES:DI to 0:0 */
ax = 0x0800;
dx = devno;
di = 0;
asm("pushw %%es; "
"movw %%di,%%es; "
"pushfl; stc; int $0x13; setc %%al; popfl; "
"popw %%es"
: "+a" (ax), "=b" (bx), "=c" (cx), "+d" (dx), "+D" (di)
: : "esi");
if ((u8)ax == 0) {
ei->legacy_max_cylinder = (cx >> 8) + ((cx & 0xc0) << 2);
ei->legacy_max_head = dx >> 8;
ei->legacy_sectors_per_track = cx & 0x3f;
}
return 0;
}
void query_edd(void)
{
char eddarg[8];
int do_mbr = 1;
int do_edd = 1;
int be_quiet;
int devno;
struct edd_info ei, *edp;
u32 *mbrptr;
if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip"))
do_mbr = 0;
else if (!strcmp(eddarg, "off"))
do_edd = 0;
}
be_quiet = cmdline_find_option_bool("quiet");
edp = boot_params.eddbuf;
mbrptr = boot_params.edd_mbr_sig_buffer;
if (!do_edd)
return;
/* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe,
* so give a hint if this happens.
*/
if (!be_quiet)
printf("Probing EDD (edd=off to disable)... ");
for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) {
/*
* Scan the BIOS-supported hard disks and query EDD
* information...
*/
get_edd_info(devno, &ei);
if (boot_params.eddbuf_entries < EDDMAXNR) {
memcpy(edp, &ei, sizeof ei);
edp++;
boot_params.eddbuf_entries++;
}
if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
}
if (!be_quiet)
printf("ok\n");
}
#endif
|
