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/* Parameters for the multiboot header */
.set ALIGN, 1<<0
.set MEMINFO, 1<<1
.set FLAGS, ALIGN | MEMINFO
.set MAGIC, 0x1BADB002
.set CHECKSUM, -(MAGIC + FLAGS)
.section .multiboot
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM
/* Allocate room for stack */
.section bss
.align 16
stack_bottom:
.skip 16384 /* 16 KiB */
stack_top:
.section .data
.intel_syntax noprefix
gdt:
null_gdt: /* null descriptor */
.quad 0x00
code_gdt:
.word 0xFFFF /* limit */
.word 0x0000 /* base */
.byte 0x00 /* base */
.byte 0x9A /* type flag (access) */
.byte 0b11001111 /* limit */
.byte 0x00 /* base */
data_gdt:
.word 0xFFFF /* limit */
.word 0x0000 /* base */
.byte 0x00 /* base */
.byte 0x92 /* type flag (access) */
.byte 0b11001111 /* limit */
.byte 0x00 /* base */
end_gdt:
gdt_desc:
.word end_gdt - gdt - 1
.int gdt
.att_syntax
.section .text
.global _start
.type _start, @function
_start:
mov $stack_top, %esp
cli
.intel_syntax noprefix
lgdt [gdt_desc] /* load GDT */
mov ax, 0x10
mov ds, ax
mov ss, ax
mov es, ax
mov fs, ax
mov gs, ax
jmp 0x08:continue
.att_syntax
continue:
call kernel_main
cli
1: hlt
jmp 1b
/* The size of the _start symbol is the current location '.' minus its start. */
.size _start, . - _start
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