Commit 62607313 authored by H. Peter Anvin's avatar H. Peter Anvin Committed by Linus Torvalds

Assembly header and main routine for new x86 setup code

The assembly header and initialization code, and the main() routine.
main.c also contains some miscellaneous very short routines.
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7052fdd8
/*
* header.S
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Based on bootsect.S and setup.S
* modified by more people than can be counted
*
* Rewritten as a common file by H. Peter Anvin (Apr 2007)
*
* BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
* addresses must be multiplied by 16 to obtain their respective linear
* addresses. To avoid confusion, linear addresses are written using leading
* hex while segment addresses are written as segment:offset.
*
*/
#include <asm/segment.h>
#include <linux/utsrelease.h>
#include <asm/boot.h>
#include <asm/e820.h>
#include <asm/page.h>
#include <asm/setup.h>
#include "boot.h"
SETUPSECTS = 4 /* default nr of setup-sectors */
BOOTSEG = 0x07C0 /* original address of boot-sector */
SYSSEG = DEF_SYSSEG /* system loaded at 0x10000 (65536) */
SYSSIZE = DEF_SYSSIZE /* system size: # of 16-byte clicks */
/* to be loaded */
ROOT_DEV = 0 /* ROOT_DEV is now written by "build" */
SWAP_DEV = 0 /* SWAP_DEV is now written by "build" */
#ifndef SVGA_MODE
#define SVGA_MODE ASK_VGA
#endif
#ifndef RAMDISK
#define RAMDISK 0
#endif
#ifndef ROOT_RDONLY
#define ROOT_RDONLY 1
#endif
.code16
.section ".bstext", "ax"
.global bootsect_start
bootsect_start:
# Normalize the start address
ljmp $BOOTSEG, $start2
start2:
movw %cs, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
xorw %sp, %sp
sti
cld
movw $bugger_off_msg, %si
msg_loop:
lodsb
andb %al, %al
jz bs_die
movb $0xe, %ah
movw $7, %bx
int $0x10
jmp msg_loop
bs_die:
# Allow the user to press a key, then reboot
xorw %ax, %ax
int $0x16
int $0x19
# int 0x19 should never return. In case it does anyway,
# invoke the BIOS reset code...
ljmp $0xf000,$0xfff0
.section ".bsdata", "a"
bugger_off_msg:
.ascii "Direct booting from floppy is no longer supported.\r\n"
.ascii "Please use a boot loader program instead.\r\n"
.ascii "\n"
.ascii "Remove disk and press any key to reboot . . .\r\n"
.byte 0
# Kernel attributes; used by setup. This is part 1 of the
# header, from the old boot sector.
.section ".header", "a"
.globl hdr
hdr:
setup_sects: .byte SETUPSECTS
root_flags: .word ROOT_RDONLY
syssize: .long SYSSIZE
ram_size: .word RAMDISK
vid_mode: .word SVGA_MODE
root_dev: .word ROOT_DEV
boot_flag: .word 0xAA55
# offset 512, entry point
.globl _start
_start:
# Explicitly enter this as bytes, or the assembler
# tries to generate a 3-byte jump here, which causes
# everything else to push off to the wrong offset.
.byte 0xeb # short (2-byte) jump
.byte start_of_setup-1f
1:
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
.word 0x0206 # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
start_sys_seg: .word SYSSEG
.word kernel_version-512 # pointing to kernel version string
# above section of header is compatible
# with loadlin-1.5 (header v1.5). Don't
# change it.
type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
# Bootlin, SYSLX, bootsect...)
# See Documentation/i386/boot.txt for
# assigned ids
# flags, unused bits must be zero (RFU) bit within loadflags
loadflags:
LOADED_HIGH = 1 # If set, the kernel is loaded high
CAN_USE_HEAP = 0x80 # If set, the loader also has set
# heap_end_ptr to tell how much
# space behind setup.S can be used for
# heap purposes.
# Only the loader knows what is free
#ifndef __BIG_KERNEL__
.byte 0
#else
.byte LOADED_HIGH
#endif
setup_move_size: .word 0x8000 # size to move, when setup is not
# loaded at 0x90000. We will move setup
# to 0x90000 then just before jumping
# into the kernel. However, only the
# loader knows how much data behind
# us also needs to be loaded.
code32_start: # here loaders can put a different
# start address for 32-bit code.
#ifndef __BIG_KERNEL__
.long 0x1000 # 0x1000 = default for zImage
#else
.long 0x100000 # 0x100000 = default for big kernel
#endif
ramdisk_image: .long 0 # address of loaded ramdisk image
# Here the loader puts the 32-bit
# address where it loaded the image.
# This only will be read by the kernel.
ramdisk_size: .long 0 # its size in bytes
bootsect_kludge:
.long 0 # obsolete
heap_end_ptr: .word _end+1024 # (Header version 0x0201 or later)
# space from here (exclusive) down to
# end of setup code can be used by setup
# for local heap purposes.
pad1: .word 0
cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
# If nonzero, a 32-bit pointer
# to the kernel command line.
# The command line should be
# located between the start of
# setup and the end of low
# memory (0xa0000), or it may
# get overwritten before it
# gets read. If this field is
# used, there is no longer
# anything magical about the
# 0x90000 segment; the setup
# can be located anywhere in
# low memory 0x10000 or higher.
ramdisk_max: .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
# (Header version 0x0203 or later)
# The highest safe address for
# the contents of an initrd
kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
#required for protected mode
#kernel
#ifdef CONFIG_RELOCATABLE
relocatable_kernel: .byte 1
#else
relocatable_kernel: .byte 0
#endif
pad2: .byte 0
pad3: .word 0
cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
#added with boot protocol
#version 2.06
# End of setup header #####################################################
.section ".inittext", "ax"
start_of_setup:
#ifdef SAFE_RESET_DISK_CONTROLLER
# Reset the disk controller.
movw $0x0000, %ax # Reset disk controller
movb $0x80, %dl # All disks
int $0x13
#endif
# We will have entired with %cs = %ds+0x20, normalize %cs so
# it is on par with the other segments.
pushw %ds
pushw $setup2
lretw
setup2:
# Force %es = %ds
movw %ds, %ax
movw %ax, %es
cld
# Stack paranoia: align the stack and make sure it is good
# for both 16- and 32-bit references. In particular, if we
# were meant to have been using the full 16-bit segment, the
# caller might have set %sp to zero, which breaks %esp-based
# references.
andw $~3, %sp # dword align (might as well...)
jnz 1f
movw $0xfffc, %sp # Make sure we're not zero
1: movzwl %sp, %esp # Clear upper half of %esp
sti
# Check signature at end of setup
cmpl $0x5a5aaa55, setup_sig
jne setup_bad
# Zero the bss
movw $__bss_start, %di
movw $_end+3, %cx
xorl %eax, %eax
subw %di, %cx
shrw $2, %cx
rep; stosl
# Jump to C code (should not return)
calll main
# Setup corrupt somehow...
setup_bad:
movl $setup_corrupt, %eax
calll puts
# Fall through...
.globl die
.type die, @function
die:
hlt
jmp die
.size die, .-due
.section ".initdata", "a"
setup_corrupt:
.byte 7
.string "No setup signature found..."
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/main.c
*
* Main module for the real-mode kernel code
*/
#include "boot.h"
struct boot_params boot_params __attribute__((aligned(16)));
char *HEAP = _end;
char *heap_end = _end; /* Default end of heap = no heap */
/*
* Copy the header into the boot parameter block. Since this
* screws up the old-style command line protocol, adjust by
* filling in the new-style command line pointer instead.
*/
#define OLD_CL_MAGIC 0xA33F
#define OLD_CL_ADDRESS 0x20
static void copy_boot_params(void)
{
struct old_cmdline {
u16 cl_magic;
u16 cl_offset;
};
const struct old_cmdline * const oldcmd =
(const struct old_cmdline *)OLD_CL_ADDRESS;
BUILD_BUG_ON(sizeof boot_params != 4096);
memcpy(&boot_params.hdr, &hdr, sizeof hdr);
if (!boot_params.hdr.cmd_line_ptr &&
oldcmd->cl_magic == OLD_CL_MAGIC) {
/* Old-style command line protocol. */
u16 cmdline_seg;
/* Figure out if the command line falls in the region
of memory that an old kernel would have copied up
to 0x90000... */
if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
cmdline_seg = ds();
else
cmdline_seg = 0x9000;
boot_params.hdr.cmd_line_ptr =
(cmdline_seg << 4) + oldcmd->cl_offset;
}
}
/*
* Set the keyboard repeat rate to maximum. Unclear why this
* is done here; this might be possible to kill off as stale code.
*/
static void keyboard_set_repeat(void)
{
u16 ax = 0x0305;
u16 bx = 0;
asm volatile("int $0x16"
: "+a" (ax), "+b" (bx)
: : "ecx", "edx", "esi", "edi");
}
/*
* Get Intel SpeedStep IST information.
*/
static void query_speedstep_ist(void)
{
asm("int $0x15"
: "=a" (boot_params.speedstep_info[0]),
"=b" (boot_params.speedstep_info[1]),
"=c" (boot_params.speedstep_info[2]),
"=d" (boot_params.speedstep_info[3])
: "a" (0x0000e980), /* IST Support */
"d" (0x47534943)); /* Request value */
}
/*
* Tell the BIOS what CPU mode we intend to run in.
*/
static void set_bios_mode(void)
{
#ifdef CONFIG_X86_64
u32 eax, ebx;
eax = 0xec00;
ebx = 2;
asm volatile("int $0x15"
: "+a" (eax), "+b" (ebx)
: : "ecx", "edx", "esi", "edi");
#endif
}
void main(void)
{
/* First, copy the boot header into the "zeropage" */
copy_boot_params();
/* End of heap check */
if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
heap_end = (char *)(boot_params.hdr.heap_end_ptr
+0x200-STACK_SIZE);
} else {
/* Boot protocol 2.00 only, no heap available */
puts("WARNING: Ancient bootloader, some functionality "
"may be limited!\n");
}
/* Make sure we have all the proper CPU support */
if (validate_cpu()) {
puts("Unable to boot - please use a kernel appropriate "
"for your CPU.\n");
die();
}
/* Tell the BIOS what CPU mode we intend to run in. */
set_bios_mode();
/* Detect memory layout */
detect_memory();
/* Set keyboard repeat rate (why?) */
keyboard_set_repeat();
/* Set the video mode */
set_video();
/* Query MCA information */
query_mca();
/* Voyager */
#ifdef CONFIG_X86_VOYAGER
query_voyager();
#endif
/* Query SpeedStep IST information */
query_speedstep_ist();
/* Query APM information */
#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
query_apm_bios();
#endif
/* Query EDD information */
#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
query_edd();
#endif
/* Do the last things and invoke protected mode */
go_to_protected_mode();
}
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