orion_old/kernel/arch/i386/boot.S

59 lines
1.3 KiB
ArmAsm

# Declare constants for the multiboot header.
.set ALIGN, 1<<0 # align loaded modules on page boundaries
.set MEMINFO, 1<<1 # provide memory map
.set FLAGS, ALIGN | MEMINFO # this is the Multiboot 'flag' field
.set MAGIC, 0x1BADB002 # 'magic number' lets bootloader find the header
.set CHECKSUM, -(MAGIC + FLAGS) # checksum of above, to prove we are multiboot
# Declare a header as in the Multiboot Standard.
.section .multiboot
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM
# Reserve a stack for the initial thread.
.section .bss
.align 16
stack_bottom:
.skip 16384 # 16 KiB
stack_top:
# The kernel entry point.
.section .text
.global _start
.type _start, @function
_start:
movl $stack_top, %esp
# Call the global constructors.
call _init
# Call early kernel (init GDT, IDT and other)
call kernel_early_main
# Transfer control to the main kernel.
call kernel_main
# Hang if kernel_main unexpectedly returns.
cli
1: hlt
jmp 1b
.size _start, . - _start
.global gdt_flush
gdt_flush:
cli
mov 0x4(%esp),%eax
sgdtl (%eax)
mov $0x10,%ax
mov %eax,%ds
mov %eax,%es
mov %eax,%fs
mov %eax,%gs
mov %eax,%ss
ljmp $0x8,$.flush
.flush:
ret