Interrupt handler works, sort of??

Something seems to be wrong with the iret out of it

rust_experiments/src/lib.rs

@@ -56,7 +56,7 @@ pub extern fn rust_main() {
             timer = 0;
         }
 
-        if count > 200 {
+        if count > 200 && count < 300 {
             unsafe {
                 call_interrupt();
             }

rust_experiments/src/long_mode_init.asm

@@ -22,6 +22,14 @@ long_mode_start:
     hlt
 
 
+spin_loop_64:
+    mov rcx, 0xffff_ffff
+    .loop:
+    dec rcx
+    cmp rcx, 0
+    jne spin_loop_64.loop
+    ret
+
 error:
     mov rbx, 0x4f4f4f524f524f45
     mov [0xb8000], rbx
@@ -62,17 +70,29 @@ get_rdtsc:
     ret
 
 call_interrupt:
-    int 50
+    int 49
     ret
 
+sample_handler:
+    mov word [0x8b000], 0x4f72
+    call spin_loop_64
+    iret
+
 setup_IDT:
     lidt [idt64.pointer]
+    mov rax, sample_handler
+    mov [idt64 + 49*16], ax
+    mov word [idt64 + 49*16 +2], cs
+    mov word [idt64 + 49*16 + 4], 0x8e00
+    shr rax, 16
+    mov [idt64 + 49*16 + 6], ax
+    shr rax, 16
+    mov [idt64 + 49*16 + 8], ax
     ret
 
-section .rodata
-    idt64:
-        resb 50*16
-    .pointer:
-        dw .pointer - idt64
-        dq idt64
+idt64:
+    resb 50*16
+.pointer:
+    dw .pointer - idt64
+    dq idt64