Struct ChainBuilder 

pub struct ChainBuilder<M: MemOps, P: BufferProvider + Clone> { /* private fields */ }

Builder for configuring a descriptor chain’s buffer layout.

If dropped without building, no resources are leaked (allocations are deferred to build).

Implementations

impl<M: MemOps, P: BufferProvider + Clone> ChainBuilder<M, P>

pub fn readable(self, cap: usize) -> Self

Request a device-readable buffer of cap bytes.

The producer writes data into readable buffers before submission; the consumer reads that data after polling the chain. The actual allocation is deferred to build.

pub fn writable(self, cap: usize) -> Self

Request a device-writable buffer of cap bytes.

The writable buffer is filled by the consumer and returned via VirtqProducer::poll as UsedChain.

Multiple writable buffers are completed as ordered Segments. The consumer writes them sequentially, because the virtio used ring reports one aggregate written length rather than per-descriptor lengths.

pub fn build(self) -> Result<SendChain<M, P>, VirtqError>

Allocate buffers and return a SendChain for writing.

Errors

• VirtqError::InvalidState - No buffers requested
• VirtqError::Alloc - Pool exhausted