| 39,13 → 39,55 |
|---|
| # switch to protected mode. |
| # |
| kernel_image_start: |
| cli |
| xorw %ax,%ax |
| movw %ax,%ds |
| movw %ax,%ss # initialize stack segment register |
| movl $0x7c00,%esp # initialize stack pointer |
| |
| call memmap_arch_init |
| |
| mov $0x80000000, %eax |
| cpuid |
| cmp $0x80000000, %eax # any function > 80000000h? |
| jbe no_long_mode |
| mov $0x80000001, %eax # Extended function code 80000001 |
| cpuid |
| bt $29, %edx # Test if long mode is supported. |
| jnc no_long_mode |
| |
| meeting_point: |
| .code32 |
| # Fill out GDTR.base, IDTR.base |
| leal gdtr, %eax |
| movl gdt_addr, %ebx |
| movl %ebx, 2(%eax) |
| |
| movl idt_addr, %ebx |
| leal idtr, %eax |
| movl %ebx, 2(%eax) |
| |
| .section K_DATA_START |
| # Load gdtr, idtr |
| lgdt gdtr |
| lidt idtr |
| |
| mov $1, %eax # Enable protected mode (CR0.PE = 1) |
| mov %eax, %cr0 |
| |
| jmpl $8, $now_in_prot |
| |
| now_in_prot: |
| |
| |
| no_long_mode: |
| 1: |
| jmp 1b |
| |
| |
| .section K_DATA_START |
| .align 4096 |
| page_directory: |
| .space 4096, 0 |
| |
| gdt_addr: |
| .quad gdt + 0x80000000 |
| idt_addr: |
| .quad idt + 0x80000000 |