static AP_REACHED_RUST: AtomicUsizeExpand description
AP ACK: set to apic_id by each AP at start of smp_main(), BSP waits for it. Sentinel usize::MAX means “no ACK yet” (avoids collision with APIC ID 0).
static AP_REACHED_RUST: AtomicUsizeAP ACK: set to apic_id by each AP at start of smp_main(), BSP waits for it. Sentinel usize::MAX means “no ACK yet” (avoids collision with APIC ID 0).