| /* ----------------------------------------------------------------------- * |
| * |
| * 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/pmjump.S |
| * |
| * The actual transition into protected mode |
| */ |
| |
| #include <asm/boot.h> |
| #include <asm/segment.h> |
| |
| .text |
| |
| .globl protected_mode_jump |
| .type protected_mode_jump, @function |
| |
| .code16 |
| |
| /* |
| * void protected_mode_jump(u32 entrypoint, u32 bootparams); |
| */ |
| protected_mode_jump: |
| movl %edx, %esi # Pointer to boot_params table |
| movl %eax, 2f # Patch ljmpl instruction |
| |
| movw $__BOOT_DS, %cx |
| xorl %ebx, %ebx # Per the 32-bit boot protocol |
| xorl %ebp, %ebp # Per the 32-bit boot protocol |
| xorl %edi, %edi # Per the 32-bit boot protocol |
| |
| movl %cr0, %edx |
| orb $1, %dl # Protected mode (PE) bit |
| movl %edx, %cr0 |
| jmp 1f # Short jump to serialize on 386/486 |
| 1: |
| |
| movw %cx, %ds |
| movw %cx, %es |
| movw %cx, %fs |
| movw %cx, %gs |
| movw %cx, %ss |
| |
| # Jump to the 32-bit entrypoint |
| .byte 0x66, 0xea # ljmpl opcode |
| 2: .long 0 # offset |
| .word __BOOT_CS # segment |
| |
| .size protected_mode_jump, .-protected_mode_jump |