1 files changed, 126 insertions, 0 deletions
diff --git a/src/arch/x86/boot/boot.S b/src/arch/x86/boot/boot.S
new file mode 100644
index 0000000..02f6e91
--- /dev/null
+++ b/src/arch/x86/boot/boot.S
@@ -0,0 +1,126 @@
+.section .bootstrap_stack, "aw", @nobits
+stack_bottom:
+.skip 16384
+stack_top:
+
+.section .bss, "aw", @nobits
+	.align 4096
+page_directory:
+	.skip 4096
+page_table1:
+	.skip 4096
+page_table2:
+	.skip 4096
+
+
+.set P,		1<<0
+.set RW,	1<<1
+.set FLAGS,	P | RW
+.set KERNEL_VM,	0xC0000000
+
+
+.section .multiboot.text, "a"
+.global _start
+.type _start, @function
+_start:
+_start:
+	cli
+	mov $stack_top - KERNEL_VM, %esp
+	pushl %eax
+	pushl %ebx
+
+	movl $page_table1 - KERNEL_VM + FLAGS, page_directory - KERNEL_VM + 0 * 4
+	movl $page_table2 - KERNEL_VM + FLAGS, page_directory - KERNEL_VM + 1 * 4
+	movl $page_table1 - KERNEL_VM + FLAGS, page_directory - KERNEL_VM + 768 * 4
+	movl $page_table2 - KERNEL_VM + FLAGS, page_directory - KERNEL_VM + 769 * 4
+
+	mov $0, %ecx
+not_done:
+	mov $0x1000, %eax
+	mul %ecx
+	orl $FLAGS, %eax
+	mov %eax, %edi
+
+	// page_table1[%ecx] = 0x1000 * %ecx | 0x3
+	mov $4, %eax
+	mul %ecx
+	add $page_table1 - KERNEL_VM, %eax
+	movl %edi, (%eax)
+
+	// page_table2[%ecx] = 0x1000 * %ecx | 0x3
+	mov $4, %eax
+	mul %ecx
+	add $1024 * 0x1000, %edi
+	add $page_table2 - KERNEL_VM, %eax
+	movl %edi, (%eax)
+
+	inc %ecx
+	cmp $1024, %ecx
+	je done
+	jmp not_done
+done:
+
+	movl $(page_directory - KERNEL_VM), %ecx
+	movl %ecx, %cr3
+
+	movl %cr0, %ecx
+	orl $0x80001000, %ecx
+	movl %ecx, %cr0
+
+	lea 7f, %ecx
+	jmp *%ecx
+
+
+.section .boot32.rodata
+
+gdt:
+gdt_null = . - gdt
+	.quad 0
+kernel_code = . - gdt
+	.long 0xFFFF
+	.byte 0
+	.byte 0x9A
+	.byte 0xCF
+	.byte 0
+kernel_data = . - gdt
+	.long 0xFFFF
+	.byte 0
+	.byte 0x92
+	.byte 0xCF
+	.byte 0
+user_code = . - gdt
+	.long 0xFFFF
+	.byte 0
+	.byte 0xFA
+	.byte 0xCF
+	.byte 0
+user_data = . - gdt
+	.long 0xFFFF
+	.byte 0
+	.byte 0xF2
+	.byte 0xCF
+	.byte 0
+
+.global gdtp
+gdtp:
+	.word . - gdt - 1
+	.long gdt
+
+
+.section .text
+
+7:
+	addl $KERNEL_VM, %esp
+	lgdtl gdtp
+	ljmp $0x08, $code
+
+code:
+	movw $0x10, %ax
+	movw %ax, %ds
+	movw %ax, %es
+	movw %ax, %fs
+	movw %ax, %gs
+	movw %ax, %ss
+
+	call kernel_main
+	hlt