SEG_DESC_UNUSABLE
if (SEG_DESC_UNUSABLE(access) || !SEG_DESC_PRESENT(access))
if (SEG_DESC_UNUSABLE(desc->access))
assert(!SEG_DESC_UNUSABLE(access) && SEG_DESC_PRESENT(access));
if (SEG_DESC_UNUSABLE(desc->access)) {
if (SEG_DESC_UNUSABLE(desc->access))