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1 /* -*- linux-c -*- ------------------------------------------------------- *
2  *
3  *   Copyright (C) 1991, 1992 Linus Torvalds
4  *   Copyright 2007 rPath, Inc. - All Rights Reserved
5  *
6  *   This file is part of the Linux kernel, and is made available under
7  *   the terms of the GNU General Public License version 2.
8  *
9  * ----------------------------------------------------------------------- */
10 
11 /*
12  * Main module for the real-mode kernel code
13  */
14 
15 #include "boot.h"
16 
17 struct boot_params boot_params __attribute__((aligned(16)));
18 
19 char *HEAP = _end;
20 char *heap_end = _end;		/* Default end of heap = no heap */
21 
22 /*
23  * Copy the header into the boot parameter block.  Since this
24  * screws up the old-style command line protocol, adjust by
25  * filling in the new-style command line pointer instead.
26  */
27 
copy_boot_params(void)28 static void copy_boot_params(void)
29 {
30 	struct old_cmdline {
31 		u16 cl_magic;
32 		u16 cl_offset;
33 	};
34 	const struct old_cmdline * const oldcmd =
35 		(const struct old_cmdline *)OLD_CL_ADDRESS;
36 
37 	BUILD_BUG_ON(sizeof boot_params != 4096);
38 	memcpy(&boot_params.hdr, &hdr, sizeof hdr);
39 
40 	if (!boot_params.hdr.cmd_line_ptr &&
41 	    oldcmd->cl_magic == OLD_CL_MAGIC) {
42 		/* Old-style command line protocol. */
43 		u16 cmdline_seg;
44 
45 		/* Figure out if the command line falls in the region
46 		   of memory that an old kernel would have copied up
47 		   to 0x90000... */
48 		if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
49 			cmdline_seg = ds();
50 		else
51 			cmdline_seg = 0x9000;
52 
53 		boot_params.hdr.cmd_line_ptr =
54 			(cmdline_seg << 4) + oldcmd->cl_offset;
55 	}
56 }
57 
58 /*
59  * Set the keyboard repeat rate to maximum.  Unclear why this
60  * is done here; this might be possible to kill off as stale code.
61  */
keyboard_set_repeat(void)62 static void keyboard_set_repeat(void)
63 {
64 	u16 ax = 0x0305;
65 	u16 bx = 0;
66 	asm volatile("int $0x16"
67 		     : "+a" (ax), "+b" (bx)
68 		     : : "ecx", "edx", "esi", "edi");
69 }
70 
71 /*
72  * Get Intel SpeedStep (IST) information.
73  */
query_ist(void)74 static void query_ist(void)
75 {
76 	/* Some older BIOSes apparently crash on this call, so filter
77 	   it from machines too old to have SpeedStep at all. */
78 	if (cpu.level < 6)
79 		return;
80 
81 	asm("int $0x15"
82 	    : "=a" (boot_params.ist_info.signature),
83 	      "=b" (boot_params.ist_info.command),
84 	      "=c" (boot_params.ist_info.event),
85 	      "=d" (boot_params.ist_info.perf_level)
86 	    : "a" (0x0000e980),	 /* IST Support */
87 	      "d" (0x47534943)); /* Request value */
88 }
89 
90 /*
91  * Tell the BIOS what CPU mode we intend to run in.
92  */
set_bios_mode(void)93 static void set_bios_mode(void)
94 {
95 #ifdef CONFIG_X86_64
96 	u32 eax, ebx;
97 
98 	eax = 0xec00;
99 	ebx = 2;
100 	asm volatile("int $0x15"
101 		     : "+a" (eax), "+b" (ebx)
102 		     : : "ecx", "edx", "esi", "edi");
103 #endif
104 }
105 
init_heap(void)106 static void init_heap(void)
107 {
108 	char *stack_end;
109 
110 	if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
111 		asm("leal %P1(%%esp),%0"
112 		    : "=r" (stack_end) : "i" (-STACK_SIZE));
113 
114 		heap_end = (char *)
115 			((size_t)boot_params.hdr.heap_end_ptr + 0x200);
116 		if (heap_end > stack_end)
117 			heap_end = stack_end;
118 	} else {
119 		/* Boot protocol 2.00 only, no heap available */
120 		puts("WARNING: Ancient bootloader, some functionality "
121 		     "may be limited!\n");
122 	}
123 }
124 
main(void)125 void main(void)
126 {
127 	/* First, copy the boot header into the "zeropage" */
128 	copy_boot_params();
129 
130 	/* End of heap check */
131 	init_heap();
132 
133 	/* Make sure we have all the proper CPU support */
134 	if (validate_cpu()) {
135 		puts("Unable to boot - please use a kernel appropriate "
136 		     "for your CPU.\n");
137 		die();
138 	}
139 
140 	/* Tell the BIOS what CPU mode we intend to run in. */
141 	set_bios_mode();
142 
143 	/* Detect memory layout */
144 	detect_memory();
145 
146 	/* Set keyboard repeat rate (why?) */
147 	keyboard_set_repeat();
148 
149 	/* Query MCA information */
150 	query_mca();
151 
152 	/* Voyager */
153 #ifdef CONFIG_X86_VOYAGER
154 	query_voyager();
155 #endif
156 
157 	/* Query Intel SpeedStep (IST) information */
158 	query_ist();
159 
160 	/* Query APM information */
161 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
162 	query_apm_bios();
163 #endif
164 
165 	/* Query EDD information */
166 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
167 	query_edd();
168 #endif
169 
170 	/* Set the video mode */
171 	set_video();
172 
173 	/* Parse command line for 'quiet' and pass it to decompressor. */
174 	if (cmdline_find_option_bool("quiet"))
175 		boot_params.hdr.loadflags |= QUIET_FLAG;
176 
177 	/* Do the last things and invoke protected mode */
178 	go_to_protected_mode();
179 }
180