1 // SPDX-License-Identifier: GPL-2.0-only
2 /* -*- linux-c -*- ------------------------------------------------------- *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007 rPath, Inc. - All Rights Reserved
6 * Copyright 2009 Intel Corporation; author H. Peter Anvin
8 * ----------------------------------------------------------------------- */
11 * Main module for the real-mode kernel code
13 #include <linux/build_bug.h>
18 struct boot_params boot_params
__attribute__((aligned(16)));
20 struct port_io_ops pio_ops
;
23 char *heap_end
= _end
; /* Default end of heap = no heap */
26 * Copy the header into the boot parameter block. Since this
27 * screws up the old-style command line protocol, adjust by
28 * filling in the new-style command line pointer instead.
30 static void copy_boot_params(void)
36 const struct old_cmdline
* const oldcmd
= absolute_pointer(OLD_CL_ADDRESS
);
38 BUILD_BUG_ON(sizeof(boot_params
) != 4096);
39 memcpy(&boot_params
.hdr
, &hdr
, sizeof(hdr
));
41 if (!boot_params
.hdr
.cmd_line_ptr
&& oldcmd
->cl_magic
== OLD_CL_MAGIC
) {
42 /* Old-style command line protocol */
46 * Figure out if the command line falls in the region
47 * of memory that an old kernel would have copied up
50 if (oldcmd
->cl_offset
< boot_params
.hdr
.setup_move_size
)
55 boot_params
.hdr
.cmd_line_ptr
= (cmdline_seg
<< 4) + oldcmd
->cl_offset
;
60 * Query the keyboard lock status as given by the BIOS, and
61 * set the keyboard repeat rate to maximum. Unclear why the latter
62 * is done here; this might be possible to kill off as stale code.
64 static void keyboard_init(void)
66 struct biosregs ireg
, oreg
;
70 ireg
.ah
= 0x02; /* Get keyboard status */
71 intcall(0x16, &ireg
, &oreg
);
72 boot_params
.kbd_status
= oreg
.al
;
74 ireg
.ax
= 0x0305; /* Set keyboard repeat rate */
75 intcall(0x16, &ireg
, NULL
);
79 * Get Intel SpeedStep (IST) information.
81 static void query_ist(void)
83 struct biosregs ireg
, oreg
;
86 * Some older BIOSes apparently crash on this call, so filter
87 * it from machines too old to have SpeedStep at all.
93 ireg
.ax
= 0xe980; /* IST Support */
94 ireg
.edx
= 0x47534943; /* Request value */
95 intcall(0x15, &ireg
, &oreg
);
97 boot_params
.ist_info
.signature
= oreg
.eax
;
98 boot_params
.ist_info
.command
= oreg
.ebx
;
99 boot_params
.ist_info
.event
= oreg
.ecx
;
100 boot_params
.ist_info
.perf_level
= oreg
.edx
;
104 * Tell the BIOS what CPU mode we intend to run in.
106 static void set_bios_mode(void)
109 struct biosregs ireg
;
114 intcall(0x15, &ireg
, NULL
);
118 static void init_heap(void)
122 if (boot_params
.hdr
.loadflags
& CAN_USE_HEAP
) {
123 stack_end
= (char *) (current_stack_pointer
- STACK_SIZE
);
124 heap_end
= (char *) ((size_t)boot_params
.hdr
.heap_end_ptr
+ 0x200);
125 if (heap_end
> stack_end
)
126 heap_end
= stack_end
;
128 /* Boot protocol 2.00 only, no heap available */
129 puts("WARNING: Ancient bootloader, some functionality may be limited!\n");
135 init_default_io_ops();
137 /* First, copy the boot header into the "zeropage" */
140 /* Initialize the early-boot console */
142 if (cmdline_find_option_bool("debug"))
143 puts("early console in setup code\n");
145 /* End of heap check */
148 /* Make sure we have all the proper CPU support */
149 if (validate_cpu()) {
150 puts("Unable to boot - please use a kernel appropriate for your CPU.\n");
154 /* Tell the BIOS what CPU mode we intend to run in */
157 /* Detect memory layout */
160 /* Set keyboard repeat rate (why?) and query the lock flags */
163 /* Query Intel SpeedStep (IST) information */
166 /* Query APM information */
167 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
171 /* Query EDD information */
172 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
176 /* Set the video mode */
179 /* Do the last things and invoke protected mode */
180 go_to_protected_mode();