/* ----------------------------------------------------------------------- * * * 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: xorl %ebx, %ebx # Flag to indicate this is a boot movl %edx, %esi # Pointer to boot_params table movl %eax, 2f # Patch ljmpl instruction jmp 1f # Short jump to flush instruction q. 1: movw $__BOOT_DS, %cx movl %cr0, %edx orb $1, %dl # Protected mode (PE) bit movl %edx, %cr0 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