所以我在四天后碰壁了。我正在使用 OSDev tut 并且已经搜索了两天。我什么都试过了。首先我意识到我在尝试 64 编译是愚蠢的，这就是为什么我得到一个“..relocation truncated to fit: rva32 against..”。我搬到了 Cygwin 32 上，现在我看不到内核中的 main 。
抱歉，如果这很愚蠢，我正在尝试在课间做这件事，但我被烧死了
boot.asm 用 >>> nasm -f elf boot.asm -o boot.o 编译
MBALIGN equ 1<<0 ; align loaded modules on page boundaries
MEMINFO equ 1<<1 ; provide memory map
FLAGS equ MBALIGN | MEMINFO ; this is the Multiboot 'flag' field
MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header
CHECKSUM equ -(MAGIC + FLAGS) ; checksum of above, to prove we are multiboot
section .multiboot
align 4
dd MAGIC
dd FLAGS
dd CHECKSUM
section .bootstrap_stack
align 4
stack_bottom:
times 16384 db 0
stack_top:
section .text
global _start
_start:
mov esp, stack_top
call kernel_main
cli
.hang:
hlt
jmp .hang
使用 >>> g++ -c kernel.cpp -o kernel.o -ffreestanding -O2 -Wall -Wextra -fno-exceptions -fno-rtti 编译的内核
#include <stddef.h>
#include <stdint.h>
/* Hardware text mode color constants. */
enum vga_color
{
COLOR_BLACK = 0,
COLOR_BLUE = 1,
COLOR_GREEN = 2,
COLOR_CYAN = 3,
COLOR_RED = 4,
COLOR_MAGENTA = 5,
COLOR_BROWN = 6,
COLOR_LIGHT_GREY = 7,
COLOR_DARK_GREY = 8,
COLOR_LIGHT_BLUE = 9,
COLOR_LIGHT_GREEN = 10,
COLOR_LIGHT_CYAN = 11,
COLOR_LIGHT_RED = 12,
COLOR_LIGHT_MAGENTA = 13,
COLOR_LIGHT_BROWN = 14,
COLOR_WHITE = 15,
};
uint8_t make_color(enum vga_color fg, enum vga_color bg)
{
return fg | bg << 4;
}
uint16_t make_vgaentry(char c, uint8_t color)
{
uint16_t c16 = c;
uint16_t color16 = color;
return c16 | color16 << 8;
}
size_t strlen(const char* str)
{
size_t ret = 0;
while ( str[ret] != 0 )
ret++;
return ret;
}
static const size_t VGA_WIDTH = 80;
static const size_t VGA_HEIGHT = 24;
size_t terminal_row;
size_t terminal_column;
uint8_t terminal_color;
uint16_t* terminal_buffer;
void terminal_initialize()
{
terminal_row = 0;
terminal_column = 0;
terminal_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
terminal_buffer = (uint16_t*) 0xB8000;
for ( size_t y = 0; y < VGA_HEIGHT; y++ )
{
for ( size_t x = 0; x < VGA_WIDTH; x++ )
{
const size_t index = y * VGA_WIDTH + x;
terminal_buffer[index] = make_vgaentry(' ', terminal_color);
}
}
}
void terminal_setcolor(uint8_t color)
{
terminal_color = color;
}
void terminal_putentryat(char c, uint8_t color, size_t x, size_t y)
{
const size_t index = y * VGA_WIDTH + x;
terminal_buffer[index] = make_vgaentry(c, color);
}
void terminal_putchar(char c)
{
terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
if ( ++terminal_column == VGA_WIDTH )
{
terminal_column = 0;
if ( ++terminal_row == VGA_HEIGHT )
{
terminal_row = 0;
}
}
}
void terminal_writestring(const char* data)
{
size_t datalen = strlen(data);
for ( size_t i = 0; i < datalen; i++ )
terminal_putchar(data[i]);
}
extern "C"
{
void kernel_main()
{
terminal_initialize();
/* Since there is no support for newlines in terminal_putchar yet, \n will
produce some VGA specific character instead. This is normal. */
terminal_writestring("Hello, kernel World!\n");
}
}
链接器调用 >>> g++ -T linker.ld -o myos.bin -ffreestanding -O2 -nostdlib -fno-exceptions boot.o kernel.o -lgcc
ENTRY(_start)
SECTIONS
{
/* Begin @ 1 MB*/
. = 1M;
/* multiboot header -> text */
.text BLOCK(4K) : ALIGN(4K)
{
*(.multiboot)
*(.text)
}
/* Read only data */
.rodata BLOCK(4K) : ALIGN(4K)
{
*(.rodata)
}
/* Read-write data */
.data BLOCK(4K) : ALIGN(4K)
{
*(.data)
}
/* Read, write, and stack */
.bss BLOCK(4K) : ALIGN(4K)
{
*(COMMON)
*(.bss)
*(.bootstrap_stack)
}
/* Additional Here */
}
也许我只是被烧毁了，没有看到简单的东西，但这就是我在这里的原因