1/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 *   Copyright (C) 1991, 1992 Linus Torvalds
4 *   Copyright 2007 rPath, Inc. - All Rights Reserved
5 *   Copyright 2009 Intel Corporation; author H. Peter Anvin
6 *
7 *   This file is part of the Linux kernel, and is made available under
8 *   the terms of the GNU General Public License version 2.
9 *
10 * ----------------------------------------------------------------------- */
11
12/*
13 * Main module for the real-mode kernel code
14 */
15
16#include "boot.h"
17#include "string.h"
18
19struct boot_params boot_params __attribute__((aligned(16)));
20
21char *HEAP = _end;
22char *heap_end = _end;		/* Default end of heap = no heap */
23
24/*
25 * Copy the header into the boot parameter block.  Since this
26 * screws up the old-style command line protocol, adjust by
27 * filling in the new-style command line pointer instead.
28 */
29
30static void copy_boot_params(void)
31{
32	struct old_cmdline {
33		u16 cl_magic;
34		u16 cl_offset;
35	};
36	const struct old_cmdline * const oldcmd =
37		(const struct old_cmdline *)OLD_CL_ADDRESS;
38
39	BUILD_BUG_ON(sizeof boot_params != 4096);
40	memcpy(&boot_params.hdr, &hdr, sizeof hdr);
41
42	if (!boot_params.hdr.cmd_line_ptr &&
43	    oldcmd->cl_magic == OLD_CL_MAGIC) {
44		/* Old-style command line protocol. */
45		u16 cmdline_seg;
46
47		/* Figure out if the command line falls in the region
48		   of memory that an old kernel would have copied up
49		   to 0x90000... */
50		if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
51			cmdline_seg = ds();
52		else
53			cmdline_seg = 0x9000;
54
55		boot_params.hdr.cmd_line_ptr =
56			(cmdline_seg << 4) + oldcmd->cl_offset;
57	}
58}
59
60/*
61 * Query the keyboard lock status as given by the BIOS, and
62 * set the keyboard repeat rate to maximum.  Unclear why the latter
63 * is done here; this might be possible to kill off as stale code.
64 */
65static void keyboard_init(void)
66{
67	struct biosregs ireg, oreg;
68	initregs(&ireg);
69
70	ireg.ah = 0x02;		/* Get keyboard status */
71	intcall(0x16, &ireg, &oreg);
72	boot_params.kbd_status = oreg.al;
73
74	ireg.ax = 0x0305;	/* Set keyboard repeat rate */
75	intcall(0x16, &ireg, NULL);
76}
77
78/*
79 * Get Intel SpeedStep (IST) information.
80 */
81static void query_ist(void)
82{
83	struct biosregs ireg, oreg;
84
85	/* Some older BIOSes apparently crash on this call, so filter
86	   it from machines too old to have SpeedStep at all. */
87	if (cpu.level < 6)
88		return;
89
90	initregs(&ireg);
91	ireg.ax  = 0xe980;	 /* IST Support */
92	ireg.edx = 0x47534943;	 /* Request value */
93	intcall(0x15, &ireg, &oreg);
94
95	boot_params.ist_info.signature  = oreg.eax;
96	boot_params.ist_info.command    = oreg.ebx;
97	boot_params.ist_info.event      = oreg.ecx;
98	boot_params.ist_info.perf_level = oreg.edx;
99}
100
101/*
102 * Tell the BIOS what CPU mode we intend to run in.
103 */
104static void set_bios_mode(void)
105{
106#ifdef CONFIG_X86_64
107	struct biosregs ireg;
108
109	initregs(&ireg);
110	ireg.ax = 0xec00;
111	ireg.bx = 2;
112	intcall(0x15, &ireg, NULL);
113#endif
114}
115
116static void init_heap(void)
117{
118	char *stack_end;
119
120	if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
121		asm("leal %P1(%%esp),%0"
122		    : "=r" (stack_end) : "i" (-STACK_SIZE));
123
124		heap_end = (char *)
125			((size_t)boot_params.hdr.heap_end_ptr + 0x200);
126		if (heap_end > stack_end)
127			heap_end = stack_end;
128	} else {
129		/* Boot protocol 2.00 only, no heap available */
130		puts("WARNING: Ancient bootloader, some functionality "
131		     "may be limited!\n");
132	}
133}
134
135void main(void)
136{
137	/* First, copy the boot header into the "zeropage" */
138	copy_boot_params();
139
140	/* Initialize the early-boot console */
141	console_init();
142	if (cmdline_find_option_bool("debug"))
143		puts("early console in setup code\n");
144
145	/* End of heap check */
146	init_heap();
147
148	/* Make sure we have all the proper CPU support */
149	if (validate_cpu()) {
150		puts("Unable to boot - please use a kernel appropriate "
151		     "for your CPU.\n");
152		die();
153	}
154
155	/* Tell the BIOS what CPU mode we intend to run in. */
156	set_bios_mode();
157
158	/* Detect memory layout */
159	detect_memory();
160
161	/* Set keyboard repeat rate (why?) and query the lock flags */
162	keyboard_init();
163
164	/* Query MCA information */
165	query_mca();
166
167	/* Query Intel SpeedStep (IST) information */
168	query_ist();
169
170	/* Query APM information */
171#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
172	query_apm_bios();
173#endif
174
175	/* Query EDD information */
176#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
177	query_edd();
178#endif
179
180	/* Set the video mode */
181	set_video();
182
183	/* Do the last things and invoke protected mode */
184	go_to_protected_mode();
185}
186