xv6-cs450/bootother.S
Frans Kaashoek bd71a45046 Make AP processors boot using bootpgdir
Remove device mapping from bootpgdir
Remove unnecessary vmenable
Set CPUS back to 2 in Makefile
Passes all usertests
2011-08-11 12:25:10 -04:00

84 lines
1.9 KiB
ArmAsm

#include "asm.h"
#include "memlayout.h"
#include "mmu.h"
# Each non-boot CPU ("AP") is started up in response to a STARTUP
# IPI from the boot CPU. Section B.4.2 of the Multi-Processor
# Specification says that the AP will start in real mode with CS:IP
# set to XY00:0000, where XY is an 8-bit value sent with the
# STARTUP. Thus this code must start at a 4096-byte boundary.
#
# Because this code sets DS to zero, it must sit
# at an address in the low 2^16 bytes.
#
# Bootothers (in main.c) sends the STARTUPs one at a time.
# It copies this code (start) at 0x7000.
# It puts the address of a newly allocated per-core stack in start-4,
# the address of the place to jump to (mpboot) in start-8, and the physical
# address of bootpgdir in start-12.
#
#
# This code is identical to bootasm.S except:
# - it does not need to enable A20
# - it uses the address at start-4, start-8, and start-12
.code16
.globl start
start:
cli
xorw %ax,%ax
movw %ax,%ds
movw %ax,%es
movw %ax,%ss
lgdt gdtdesc
movl %cr0, %eax
orl $CR0_PE, %eax
movl %eax, %cr0
//PAGEBREAK!
ljmpl $(SEG_KCODE<<3), $(start32)
.code32
start32:
movw $(SEG_KDATA<<3), %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw $0, %ax
movw %ax, %fs
movw %ax, %gs
# Use bootpgdir as our initial page table
movl (start-12), %eax
movl %eax, %cr3
# Turn on paging.
movl %cr0, %eax
orl $(CR0_PE|CR0_PG|CR0_WP), %eax
movl %eax, %cr0
# Switch to the stack allocated by bootothers()
movl (start-4), %esp
# Call mpboot()
call *(start-8)
movw $0x8a00, %ax
movw %ax, %dx
outw %ax, %dx
movw $0x8ae0, %ax
outw %ax, %dx
spin:
jmp spin
.p2align 2
gdt:
SEG_NULLASM
SEG_ASM(STA_X|STA_R, 0, 0xffffffff)
SEG_ASM(STA_W, 0, 0xffffffff)
gdtdesc:
.word (gdtdesc - gdt - 1)
.long gdt