diff options
Diffstat (limited to 'arch/x86/boot/pmjump.S')
| -rw-r--r-- | arch/x86/boot/pmjump.S | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S new file mode 100644 index 0000000..2e55923 --- /dev/null +++ b/arch/x86/boot/pmjump.S @@ -0,0 +1,54 @@ +/* ----------------------------------------------------------------------- * + * + * 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 |