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1.1 nbrk 1: /*-
2: * Copyright (c) 2005-2007, Kohsuke Ohtani
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. Neither the name of the author nor the names of any co-contributors
14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: */
29:
30: /*
31: * head.S - low level platform support
32: */
33:
34: #include <conf/config.h>
35: #include "platform.h"
36:
37: #define SCREEN_80x25 1
38: /* #define SCREEN_80x50 1 */
39:
40: #define SEL_CODE32 0x10
41: #define SEL_DATA32 0x18
42:
43: #define ENTRY(x) .global x; .align; x##:
44:
45: .text
46: .code16
47:
48: /*
49: * boot_entry - Entry point for prex boot loader
50: */
51: ENTRY(boot_entry)
52: cld
53: cli
54:
55: /*
56: * Relocate boot loader
57: */
58: movw %cs, %ax
59: movw %ax, %ds
60: xorw %si, %si
61: movw %si, %es
62: movw $0x4000, %di /* Relocation address 0:4000 */
63: movw $0x800, %cx /* size 0x2000 */
64: rep movsl
65: ljmp $0x0000, $(reset_cs)
66: reset_cs:
67:
68: movw %cs, %ax /* Reset segment registers */
69: movw %ax, %ds
70:
71: xorw %ax, %ax /* Reset stack */
72: movw %ax, %ss
73: movw $(BOOT_STACK+0x800), %sp
74:
75: call setup_screen
76: call get_memsize
77: cli /* Disable all interrupts */
78: call enable_a20 /* Enable A20 line */
79:
80: lgdt gdt_desc /* Load GDT */
81:
82: movl %cr0, %eax /* Switch to protected mode */
83: orl $0x1, %eax
84: movl %eax, %cr0
85:
86: .byte 0x66 /* 32-bit long jump to reset CS */
87: .byte 0xea
88: .long go_prot
89: .word SEL_CODE32
90: .code32
91: .align 4
92: go_prot:
93: movw $(SEL_DATA32), %ax /* Reset data segments */
94: movw %ax, %ds
95: movw %ax, %es
96: movw %ax, %ss
97: movw %ax, %fs
98: movw %ax, %gs
99: /*
100: * Relocate archive file
101: */
102: movl $(ARCHIVE_START), %edi /* Relocation target */
103: movl $0x32000, %esi
104: movl $0x1B8000, %ecx /* size 0x6e000 */
105: rep movsl
106:
107: jmp loader_main /* Jump to main routine in C */
108:
109: /*
110: * get_memsize - Get memory size
111: */
112: .code16
113: get_memsize:
114: xorl %eax, %eax
115: int $0x12 /* Get conventional memory size */
116: movl %eax, lo_mem /* ax = K bytes */
117:
118: mov $0x88, %ah
119: int $0x15
120: andb $0xfc, %al /* Adjust to page boundary */
121: movl %eax, hi_mem /* ax = K bytes at 100000h */
122: ret
123:
124: /*
125: * enable_a20 - Enable A20
126: */
127: .code16
128: enable_a20:
129: call empty_8042
130: movb $0xd1, %al
131: outb %al, $0x64
132: call empty_8042
133: movb $0xdf, %al
134: outb %al, $0x60
135: call empty_8042
136: wait_enable:
137: ret
138:
139: /*
140: * empty_8042 - Empty 8042
141: */
142: empty_8042:
143: pushw %ax
144: retry:
145: call io_delay
146: inb $0x64, %al
147: testb $1, %al
148: jz no_output
149:
150: call io_delay
151: inb $0x60, %al
152: jmp retry
153:
154: no_output:
155: testb $2, %al
156: jnz retry
157: popw %ax
158: ret
159:
160: /*
161: * io_delay - I/O delay
162: */
163: io_delay:
164: pushw %ax
165: inb $0x80, %al
166: inb $0x80, %al
167: popw %ax
168: ret
169:
170: /*
171: * Setup screen
172: */
173: setup_screen:
174: pushaw
175: pushw %es
176: pushw %ds
177: pushw %bp
178: movb $0x2e, %al /* print '.' for verify */
179: movb $0x0e, %ah
180: movw $0x07, %bx
181: int $0x10
182:
183: movw $0x3, %ax /* Use mode-3 */
184: int $0x10
185: movw $0x1202, %ax /* 400 scan lines */
186: movb $0x30, %bl
187: int $0x10
188: #if SCREEN_80x50
189: movw $0x1112, %ax /* Load 8x8 character set */
190: movb $0x0, %bl
191: int $0x10
192: movw $0x1201, %ax /* Turn off cursor emulation */
193: movb $0x34, %bl
194: int $0x10
195: movb $0x01, %ah /* Set cursor type */
196: movw $0x0607, %cx
197: int $0x10
198: #endif
199: popw %bp
200: popw %ds
201: popw %es
202: popaw
203: ret
204:
205: .code32
206: /*
207: * Start kernel
208: */
209: ENTRY(start_kernel)
210: movl 4(%esp), %eax
211: movl 8(%esp), %ebx /* Store multiboot information in EBX */
212: movl %eax, kern_start
213: jmp code_flush
214: code_flush:
215:
216: /* Prepare registers for kernel */
217: movw $(SEL_DATA32), %ax
218: movw %ax, %ds
219: movw %ax, %es
220: movw %ax, %fs
221: movw %ax, %gs
222:
223: xorl %eax, %eax
224: movl %eax, %ecx
225: movl %eax, %edx
226: movl %eax, %esi
227: movl %eax, %edi
228:
229: movl $0x2BADB002, %eax /* Store multiboot magic in EAX */
230: cli
231:
232: .byte 0xea
233: kern_start:
234: .long 0
235: .word SEL_CODE32
236:
237: /*
238: * Data
239: */
240: .align 16
241: gdt:
242: .word 0x0,0x0,0x0,0x0 /* 0x00 - Null descritor */
243: .word 0x0,0x0,0x0,0x0 /* 0x08 - Null descritor */
244: .word 0xffff,0x0,0x9a00,0xcf /* 0x10 - 32 bit code segment */
245: .word 0xffff,0x0,0x9200,0xcf /* 0x18 - 32 bit data segment */
246: .word 0xffff,0x0,0x9a00,0x0 /* 0x20 - 16 bit code segment */
247: .word 0xffff,0x0,0x9200,0x0 /* 0x28 - 16 bit data segment */
248:
249: gdt_desc:
250: .word 0x2F /* limit */
251: .long gdt /* address */
252:
253: .word 0x0 /* alignment */
254: idt_desc:
255: .word 0x0
256: .long 0x0
257:
258: e820_buf:
259: .space 20
260:
261: .align 16
262: .global lo_mem, hi_mem
263: lo_mem:
264: .long 0x0
265: hi_mem:
266: .long 0x0
267:
268: /*
269: * Pad data
270: */
271: .section .tail,"a"
272: dummy:
273: .byte 0xff