wip: assembly to switch to long-mode

4 files changed, 165 insertions, 18 deletions

diff --git a/src/boot.s b/src/boot.s
deleted file mode 100644
index 2530d18..0000000
--- a/src/boot.s
+++ /dev/null
@@ -1,17 +0,0 @@
-.global _start
-.type _start, @function
-
-.code32
-// Entry point. It puts the machine into a consistent state,
-// starts the kernel and then waits forever.
-_start:
-    mov _sstack, %esp  // Setup the stack.
-
-    push %ebx   // Pass multiboot info structure.
-    push %eax   // Pass multiboot magic code.
-    call kmain  // Call the kernel.
-
-    // Halt the CPU.
-    cli
-    hlt
-
diff --git a/src/boot32.s b/src/boot32.s
new file mode 100644
index 0000000..04b509f
--- /dev/null
+++ b/src/boot32.s
@@ -0,0 +1,143 @@
+.global _start
+.extern long_mode_start
+
+.section .text
+.code32
+
+// Entry point. It puts the machine into a consistent state and starts long mode.
+_start:
+    mov $0x80000, %esp  // Setup the stack.
+    push %ebx           // Pass multiboot info structure.
+    push %eax           // Pass multiboot magic code.
+
+	call check_multiboot
+	call check_cpuid
+	call check_long_mode
+
+	//call setup_page_tables
+	//call enable_paging
+
+	//lgdt [gdt64.pointer]
+	//jmp gdt64.code_segment:long_mode_start
+
+	call halt
+halt:
+	hlt
+
+check_multiboot:
+	cmp $0x36d76289, %eax 
+	jne .no_multiboot
+	ret
+.no_multiboot:
+	mov 'M', %al 
+	jmp error
+
+check_cpuid:
+	pushfd
+	pop %eax
+	mov %eax, %ecx 
+	xor $(1 << 21), %eax 
+	push %eax
+	popfd
+	pushfd
+	pop %eax
+	push %ecx
+	popfd
+	cmp %eax, %ecx
+	je .no_cpuid
+	ret
+.no_cpuid:
+	mov 'C', %al 
+	jmp error
+
+check_long_mode:
+	mov $0x80000000, %eax 
+	cpuid
+	cmp $0x80000001, %eax 
+	jb .no_long_mode
+
+	mov $0x80000001, %eax 
+	cpuid
+	test $(1 << 29), %edx 
+	jz .no_long_mode
+	
+	ret
+.no_long_mode:
+	mov 'L', %al 
+	jmp error
+
+//setup_page_tables:
+//	mov eax, page_table_l3
+//	or eax, 0b11 ; present, writable
+//	mov [page_table_l4], eax
+//	
+//	mov eax, page_table_l2
+//	or eax, 0b11 ; present, writable
+//	mov [page_table_l3], eax
+//
+//	mov ecx, 0 ; counter
+//.loop:
+//
+//	mov eax, 0x200000 ; 2MiB
+//	mul ecx
+//	or eax, 0b10000011 ; present, writable, huge page
+//	mov [page_table_l2 + ecx * 8], eax
+//
+//	inc ecx ; increment counter
+//	cmp ecx, 512 ; checks if the whole table is mapped
+//	jne .loop ; if not, continue
+//
+//	ret
+//
+//enable_paging:
+//	; pass page table location to cpu
+//	mov eax, page_table_l4
+//	mov cr3, eax
+//
+//	; enable PAE
+//	mov eax, cr4
+//	or eax, 1 << 5
+//	mov cr4, eax
+//
+//	; enable long mode
+//	mov ecx, 0xC0000080
+//	rdmsr
+//	or eax, 1 << 8
+//	wrmsr
+//
+//	; enable paging
+//	mov eax, cr0
+//	or eax, 1 << 31
+//	mov cr0, eax
+//
+//	ret
+
+error:
+	// // print "ERR: X" where X is the error code
+	movl $0x4f524f45, 0xb8000 
+	// mov dword [0xb8004], 0x4f3a4f52
+	// mov dword [0xb8008], 0x4f204f20
+	// mov byte  [0xb800a], al
+	hlt
+
+//section .bss
+//align 4096
+//page_table_l4:
+//	resb 4096
+//page_table_l3:
+//	resb 4096
+//page_table_l2:
+//	resb 4096
+//stack_bottom:
+//	resb 4096 * 4
+//stack_top:
+//
+//section .rodata
+//gdt64:
+//	dq 0 ; zero entry
+//.code_segment: equ $ - gdt64
+//	dq (1 << 43) | (1 << 44) | (1 << 47) | (1 << 53) ; code segment
+//.pointer:
+//	dw $ - gdt64 - 1 ; length
+//	dq gdt64 ; address
+//
\ No newline at end of file
diff --git a/src/boot64.s b/src/boot64.s
new file mode 100644
index 0000000..493912b
--- /dev/null
+++ b/src/boot64.s
@@ -0,0 +1,16 @@
+.global long_mode_start
+.extern kmain
+
+.section .text
+.code64
+long_mode_start:
+    // load null into all data segment registers
+    mov $0, %ax
+    mov %ax, %ss 
+    mov %ax, %ds 
+    mov %ax, %es 
+    mov %ax, %fs 
+    mov %ax, %gs 
+
+	call kmain
+    hlt
\ No newline at end of file
diff --git a/src/main.zig b/src/main.zig
index f3ea424..5534a84 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,8 +1,10 @@
 comptime {
-    asm (@embedFile("boot.s"));
+    asm (@embedFile("boot64.s"));
+    asm (@embedFile("boot32.s"));
 }
 
 const debug = @import("debugcon.zig");
+const console = @import("console.zig");
 
 const ALIGN = 1 << 0;
 const MEMINFO = 1 << 1;
@@ -37,6 +39,9 @@ export fn kmain() noreturn {
     vga[0] = 0x2f4f;
     vga[1] = 0x2f4b;
 
+    console.initialize();
+    console.puts("test");
+
     // write debug data
     debug.outb(0xe9, 'H');
     debug.outb(0xe9, 'i');