x01.os.21: print "Loading..."

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先把目标设低点，开机进入后，在屏幕上打印“Loading..."即可。由于要在 bochs 中运行，首先就是安装 bochs。Oldlinux 中有相关资源，可自行下载。winxp 和 linux 的配置脚本如下：

# for windows bochs config

megs : 

romimage: file=$BXSHARE/BIOS-bochs-latest
vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest

floppya: 1_44="a.img", status=inserted
floppyb: 1_44="b.img", status=inserted
ata0-master: type=disk, path="c.img", cylinders=, heads=, spt=

boot: a

mouse: enabled=

winxp

# for linux bochs config

display_library : sdl
megs : 

romimage : file=/usr/share/bochs/BIOS-bochs-latest
vgaromimage : file=/usr/share/vgabios/vgabios.bin

floppya: 1_44="a.img", status=inserted
floppyb: 1_44="b.img", status=inserted
ata0-master: type=disk, path="c.img", cylinders=, heads=, spt=

boot : a

mouse : enabled=
keyboard_mapping : enabled=, map=/usr/share/bochs/keymaps/sdl-pc-us.map 

linux

当然，这只是作为参考。如是 winxp，建议直接在 bochs-sls1.0 中编译，用 dd 写入 /dev/fd1, 即 b.img；如是 ubuntu，我使用 eclipse，贪图智能提示而已，本质并无区别。github 中的代码为 Ubuntu 系统。由于要求简单，代码自然也简单，分别为 makefile, boot/bootsect.s, tools/build.c 如下：

# makefile

AS86 = as86 - -a
LD86 = ld86 -

AS = as
LD = ld
LDFLAGS = -s -x -M
CC = gcc
CFLAGS = -Wall -O -fstrength-reduce -fomit-frame-pointer -nostdinc -Iinclude
CPP = gcc -E -nostdinc -Iinclude

ROOT_DEV = /dev/hd1

.c.s:
    $(CC) $(CFLAGS) -S -o $*.s $<
.s.o:
    $(AS) -c -o $*.o $<
.c.o:
    $(CC) $(CFLAGS) -c -o $*.o $<

Image: boot/bootsect tools/build
    tools/build boot/bootsect > Image
    sync

boot/bootsect: boot/bootsect.s
    $(AS86) -o boot/bootsect.o boot/bootsect.s
    $(LD86) -o boot/bootsect boot/bootsect.o

tools/build: tools/build.c
    gcc -o tools/build tools/build.c

makefile

! boot/bootsect.s

.text

entry start
start:
    mov ax, #0x07c0
    mov ds, ax
    mov es, ax
    mov ss, ax
    mov sp, #0xff00

    mov cx, #
    mov bx, #0x000c
    mov bp, #msg
    mov ax, #0x1301
    int 0x10 

die:
    jmp die 

msg:
    .byte ,,,
    .ascii "Loading..."
    .byte ,,,

    .org
    .word 0xaa55
    

boot/bootsect.s

/*
 * tools/build.c
 */

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/fs.h>
#include <unistd.h>
#include <fcntl.h>

#define MINIX_HEADER        32
#define GCC_HEADER            1024
#define SYS_SIZE            0x2000
#define DEFAULT_MAJOR_ROOT    3
#define DEFAULT_MINOR_ROOT    1
#define SETUP_SECTS            4

void die(char* str)
{
    fprintf(stderr, "%s\n", str);
    exit();
}

int main(int argc, char** argv)
{
    int i, id, c;
    char buf[];
    char major_root, minor_root;

    if (argc == ) {
    } else {
        major_root = DEFAULT_MAJOR_ROOT;
        minor_root = DEFAULT_MINOR_ROOT;
    }
    fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
    for (i = ; i < sizeof buf; i++)
        buf[i] = ;

    if ((id = open(argv[], O_RDONLY, )) < )
        die("Unable open bootsect");
    if (read(id, buf, MINIX_HEADER) != MINIX_HEADER)
        die("Unable read Minix header");
    i = read(id, buf, sizeof buf);
    fprintf(stderr, "bootsect is %d bytes.\n", i);
    buf[] = (char)major_root;
    buf[] = (char)minor_root;
    if ((*(unsigned short*)(buf + )) != 0xaa55)
        die("boot hasn't '0xaa55' flag.");
    i = write(, buf, );
    if (i != )
        die("write call failed.");
    close(id);

    return ;
}

tools/build.c

源代码：https://github.com/chinax01/Lab

在 ubuntu 中进入目录后运行如下命令即可：

make

make editcopy

bochs