Struct RingHeader 

#[repr(C, align(64))]
pub struct RingHeader {
    magic: u32,
    capacity: u32,
    slot_size: u32,
    flags: AtomicU32,
    _pad1: [u8; 48],
    head: AtomicU32,
    notify_prod: AtomicU32,
    _pad2: [u8; 56],
    tail: AtomicU32,
    notify_cons: AtomicU32,
    _pad3: [u8; 56],
}

Shared ring header, placed at the start of the first physical page.

Cache-line layout (x86-64, 64-byte lines):

• Line 0: magic, capacity, slot_size, flags (read-mostly, rarely written)
• Line 1: head, notify_prod (written by consumer, read by producer)
• Line 2: tail, notify_cons (written by producer, read by consumer)

Fields

magic: u32

Magic number for validating shared mappings.

capacity: u32

Total number of slots (must be power of two).

slot_size: u32

Usable bytes per slot.

flags: AtomicU32

Flags field (bit 0 = initialised, bit 1 = producer_ready).

_pad1: [u8; 48]

head: AtomicU32

Next slot to read. Written by consumer; read by producer.

notify_prod: AtomicU32

Notification counter for the producer (written by consumer).

_pad2: [u8; 56]

tail: AtomicU32

Next slot to write. Written by producer; read by consumer.

notify_cons: AtomicU32

Notification counter for the consumer (written by producer).

_pad3: [u8; 56]