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# Multiboot header, for multiboot boot loaders like GNU Grub.
# http://www.gnu.org/software/grub/manual/multiboot/multiboot.html
#
# Using GRUB 2, you can boot xv6 from a file stored in a
# Linux file system by copying kernel or kernelmemfs to /boot
# and then adding this menu entry:
#
# menuentry "xv6" {
# insmod ext2
# set root='(hd0,msdos1)'
# set kernel='/boot/kernel'
# echo "Loading ${kernel}..."
# multiboot ${kernel} ${kernel}
# boot
# }
#include "asm.h"
#include "memlayout.h"
#include "mmu.h"
#include "param.h"
# Multiboot header. Data to direct multiboot loader.
.p2align 2
.text
.globl multiboot_header
multiboot_header:
#define magic 0x1badb002
#define flags 0
.long magic
.long flags
.long (-magic-flags)
# By convention, the _start symbol specifies the ELF entry point.
# Since we haven't set up virtual memory yet, our entry point is
# the physical address of 'entry'.
.globl _start
_start = V2P_WO(entry)
# Entering xv6 on boot processor, with paging off.
.globl entry
entry:
# Turn on page size extension for 4Mbyte pages
movl %cr4, %eax
orl $(CR4_PSE), %eax
movl %eax, %cr4
# Set page directory
movl $(V2P_WO(entrypgdir)), %eax
movl %eax, %cr3
# Turn on paging.
movl %cr0, %eax
orl $(CR0_PG|CR0_WP), %eax
movl %eax, %cr0
# Set up the stack pointer.
movl $(stack + KSTACKSIZE), %esp
# Jump to main(), and switch to executing at
# high addresses. The indirect call is needed because
# the assembler produces a PC-relative instruction
# for a direct jump.
mov $main, %eax
jmp *%eax
.comm stack, KSTACKSIZE