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1.1 root 1: /*
2: * Ported to boot 386BSD by Julian Elischer ([email protected]) Sept 1992
3: *
4: * Mach Operating System
5: * Copyright (c) 1992, 1991 Carnegie Mellon University
6: * All Rights Reserved.
7: *
8: * Permission to use, copy, modify and distribute this software and its
9: * documentation is hereby granted, provided that both the copyright
10: * notice and this permission notice appear in all copies of the
11: * software, derivative works or modified versions, and any portions
12: * thereof, and that both notices appear in supporting documentation.
13: *
14: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
15: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
16: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
17: *
18: * Carnegie Mellon requests users of this software to return to
19: *
20: * Software Distribution Coordinator or [email protected]
21: * School of Computer Science
22: * Carnegie Mellon University
23: * Pittsburgh PA 15213-3890
24: *
25: * any improvements or extensions that they make and grant Carnegie Mellon
26: * the rights to redistribute these changes.
27: */
28:
29: /*
30: * HISTORY
31: * $Log: table.c,v $
32: * Revision 1.1 1993/03/21 18:08:47 cgd
33: * after 0.2.2 "stable" patches applied
34: *
35: * Revision 2.2 92/04/04 11:36:43 rpd
36: * Fix Intel Copyright as per B. Davies authorization.
37: * [92/04/03 rvb]
38: * Taken from 2.5 bootstrap.
39: * [92/03/30 rvb]
40: *
41: * Revision 2.2 91/04/02 14:42:22 mbj
42: * Add Intel copyright
43: * [90/02/09 rvb]
44: *
45: */
46:
47: /*
48: Copyright 1988, 1989, 1990, 1991, 1992
49: by Intel Corporation, Santa Clara, California.
50:
51: All Rights Reserved
52:
53: Permission to use, copy, modify, and distribute this software and
54: its documentation for any purpose and without fee is hereby
55: granted, provided that the above copyright notice appears in all
56: copies and that both the copyright notice and this permission notice
57: appear in supporting documentation, and that the name of Intel
58: not be used in advertising or publicity pertaining to distribution
59: of the software without specific, written prior permission.
60:
61: INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
62: INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
63: IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
64: CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
65: LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
66: NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
67: WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
68: */
69:
70: #define NGDTENT 6
71: #define GDTLIMIT 48 /* NGDTENT * 8 */
72:
73: /* Segment Descriptor
74: *
75: * 31 24 19 16 7 0
76: * ------------------------------------------------------------
77: * | | |B| |A| | | |1|0|E|W|A| |
78: * | BASE 31..24 |G|/|0|V| LIMIT |P|DPL| TYPE | BASE 23:16 |
79: * | | |D| |L| 19..16| | |1|1|C|R|A| |
80: * ------------------------------------------------------------
81: * | | |
82: * | BASE 15..0 | LIMIT 15..0 |
83: * | | |
84: * ------------------------------------------------------------
85: */
86:
87: struct seg_desc {
88: unsigned short limit_15_0;
89: unsigned short base_15_0;
90: unsigned char base_23_16;
91: unsigned char bit_15_8;
92: unsigned char bit_23_16;
93: unsigned char base_31_24;
94: };
95:
96:
97: struct seg_desc Gdt[NGDTENT] = {
98: {0x0, 0x0, 0x0, 0x0, 0x0, 0x0}, /* 0x0 : null */
99: {0xFFFF, 0x0, 0x0, 0x9F, 0xCF, 0x0}, /* 0x08 : kernel code */
100: {0xFFFF, 0x0, 0x0, 0x93, 0xCF, 0x0}, /* 0x10 : kernel data */
101: {0xFFFF, 0x0000, 0x9, 0x9E, 0x40, 0x0}, /* 0x18 : boot code */
102: {0xFFFF, 0x0000, 0x9, 0x92, 0x40, 0x0}, /* 0x20 : boot data */
103: {0xFFFF, 0x0000, 0x9, 0x9E, 0x0, 0x0} /* 0x28 : boot code, 16 bits */
104: };
105:
106:
107: struct pseudo_desc {
108: unsigned short limit;
109: unsigned short base_low;
110: unsigned short base_high;
111: };
112:
113: struct pseudo_desc Gdtr = { GDTLIMIT, 0x0400, 9 };
114: struct pseudo_desc Gdtr2 = { GDTLIMIT, 0xfe00, 9 };
115: /* boot is loaded at 0x90000, Gdt is at boot+1024 */
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