Initial commit: SUB-OS 64-Bit Production Monolithic Operating System with LazyBox userland suite

arch/x86_64/cpu/gdt_load.asm

@@ -0,0 +1,29 @@
+[BITS 64]
+
+global gdt_flush
+global tss_flush
+
+section .text
+gdt_flush:
+    lgdt [rdi]
+    ; Reload data segments
+    mov ax, 0x10
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+    mov ss, ax
+
+    ; Reload CS via far return
+    push 0x08
+    lea rax, [rel .reload_cs]
+    push rax
+    retfq
+
+.reload_cs:
+    ret
+
+tss_flush:
+    mov ax, 0x28
+    ltr ax
+    ret