Initial commit

src/entry.S

@@ -0,0 +1,71 @@
+.section .multiboot
+.include "multiboot2header.S"
+
+.section .bss
+
+.align 16
+stackBottom:
+.skip 16384
+stackTop:
+
+.align 4096
+_tempPgDir:
+.skip 4096
+_tempIdentityMap:
+.skip 4096
+_tempPgTable:
+.skip 4096
+
+.section .text
+.global _start
+.type _start, @function
+_start:
+	cmp $0x36d76289, %eax
+	jne _err
+
+	movb $64, 0xB8000
+
+	mov $0, %ecx
+1:	mov %ecx, %eax
+	mov $4096, %edx
+	mul %edx
+	add $PHYSICAL_BASE, %eax
+	or $3, %eax
+	mov $_tempPgTable, %edi
+	mov %eax, (%edi, %ecx, 4)
+	mov $_tempIdentityMap, %edi
+	mov %eax, 1024(%edi, %ecx, 4)
+	inc %ecx
+	cmp $IMAGE_SIZE, %ecx
+	jne 1b
+
+	mov $_tempIdentityMap, %eax
+	or $3, %eax
+	mov %eax, (_tempPgDir)
+
+	mov $_tempPgTable, %eax
+	or $3, %eax
+	mov %eax, (_tempPgDir + 3072)
+
+	mov $_tempPgDir, %eax
+	mov %eax, %cr3
+
+	mov %cr0, %eax
+	or $0x80010000, %eax
+	mov %eax, %cr0
+	lea 2f, %eax
+	jmp *%eax
+2:	movl $0, (_tempIdentityMap)
+	mov %cr3, %eax
+	mov %eax, %cr3
+
+	mov $stackTop, %esp
+
+	call main
+
+_err:
+	cli
+3:	hlt
+	jmp 3b
+
+.size _start, . - _start