Struct Layout 

pub struct Layout { /* private fields */ }

Layout of a packed virtqueue ring in shared memory.

Describes the memory addresses for the descriptor table and event suppression structures. Use from_base to compute the layout from a base address, or query_size to determine memory requirements.

Memory Layout

The packed ring consists of:

1. Descriptor table: num_descs × 16 bytes, aligned to 16 bytes
2. Driver event suppression: 4 bytes, aligned to 4 bytes
3. Device event suppression: 4 bytes, aligned to 4 bytes

Implementations

impl Layout

pub const unsafe fn from_base( base: u64, num_descs: NonZeroU16, ) -> Result<Self, RingError>

Create a Layout from a base address and number of descriptors.

The base address must be aligned to Descriptor::ALIGN. The number of descriptors must be a power of 2. The memory region starting at base must be at least Layout::query_size(num_descs) bytes.

Safety

• base must be valid for Layout::query_size(num_descs) bytes.
• base must be aligned to Descriptor::ALIGN.
• Memory must remain valid for the lifetime of the ring.

pub const fn desc_table_addr(&self) -> u64

Packed ring descriptor table base in shared memory.

pub const fn desc_table_len(&self) -> u16

Number of descriptors in the ring.

pub const fn drv_evt_addr(&self) -> u64

Driver-written event suppression area in shared memory.

pub const fn dev_evt_addr(&self) -> u64

Device-written event suppression area in shared memory.

pub const fn query_size(num_descs: usize) -> usize

Calculate the memory size needed for a ring with num_descs descriptors, accounting for alignment requirements.

Trait Implementations

impl Clone for Layout

fn clone(&self) -> Layout

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Layout

impl Debug for Layout

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.