gdt_ptr
static struct gdt_ptr gdt;
static const struct gdt_ptr null_idt = {0, 0};
struct desc_ptr gdt_ptr;
native_store_gdt(&gdt_ptr);
gdt = (struct desc_struct *)((void *)(gdt_ptr.address));
input->vp_context.gdtr.limit = gdt_ptr.size;
input->vp_context.gdtr.base = gdt_ptr.address;