/* Original Open Agila Multiboot v1 entry. QEMU x86-64/BIOS target only. */
.section .multiboot,"a"
.balign 4
.long 0x1badb002
.long 0x00000003
.long -(0x1badb002 + 0x00000003)
.section .text.boot,"ax"
.code32
.global _start
.type _start,@function
_start:
    cli
    cld
    mov %eax, boot_magic
    mov $stack_top, %esp
    /* GRUB enters 32-bit protected mode. Map the first GiB with 2 MiB pages.
       These writable executable boot mappings are NOT process isolation. */
    mov $pdpt, %eax
    or $3, %eax
    mov %eax, pml4
    mov $page_directory, %eax
    or $3, %eax
    mov %eax, pdpt
    xor %ecx, %ecx
1:
    mov %ecx, %eax
    shl $21, %eax
    or $0x83, %eax
    mov %eax, page_directory(,%ecx,8)
    inc %ecx
    cmp $512, %ecx
    jne 1b
    mov %cr4, %eax
    or $0x20, %eax
    mov %eax, %cr4
    mov $pml4, %eax
    mov %eax, %cr3
    mov $0xc0000080, %ecx
    rdmsr
    or $0x100, %eax
    wrmsr
    lgdt gdt_pointer
    mov %cr0, %eax
    or $0x80000000, %eax
    mov %eax, %cr0
    ljmp $0x08, $long_mode
.code64
long_mode:
    mov $0x10, %ax
    mov %ax, %ds
    mov %ax, %es
    mov %ax, %ss
    xor %eax, %eax
    mov %ax, %fs
    mov %ax, %gs
    mov $stack_top, %rsp
    xor %rbp, %rbp
    mov boot_magic(%rip), %edi
    call agila_boot_main
2:  cli
    hlt
    jmp 2b
.section .rodata,"a"
.balign 8
gdt:
    .quad 0
    .quad 0x00af9a000000ffff
    .quad 0x00cf92000000ffff
gdt_end:
gdt_pointer:
    .word gdt_end-gdt-1
    .long gdt
.section .bss,"aw",@nobits
.balign 4
boot_magic: .skip 4
.balign 4096
pml4: .skip 4096
pdpt: .skip 4096
page_directory: .skip 4096
.balign 16
stack_bottom: .skip 65536
stack_top:
.section .note.GNU-stack,"",@progbits