Struct Virtqueue

pub struct Virtqueue {
    pub descriptor_table: Mapped<[Descriptor]>,
    pub available_ring: Mapped<AvailableRing>,
    pub used_ring: Mapped<UsedRing>,
    /* private fields */
}

A virtqueue is the mechanism used for bulk data transport to and from Virtio devices. We use the split virtqueue representation - the first format of virtqueue supported by Virtio.

Buffers can be added to the virtqueue to make requests of the device. Devices then execute these requests, and when complete, mark the buffers as ‘used’ by the device.

A split virtqueue is comprised of three “areas”, each of which can be separately allocated:

• The Descriptor Table (of size 16 * Queue Size)
• The Available Ring (of size 6 + 2 * Queue Size)
• The Used Ring (of size 6 + 8 * Queue Size) The queue size is found in a transport-specific way (and is a maximum of 32768).

Fields

descriptor_table: Mapped<[Descriptor]>

available_ring: Mapped<AvailableRing>

used_ring: Mapped<UsedRing>

Implementations

impl Virtqueue

pub fn new<M>(queue_size: u16, mapper: &M) -> Virtqueue

where M: Mapper,

pub fn push_descriptor(&mut self, index: u16, descriptor: Descriptor)

Push a descriptor into the descriptor table, returning its index. Returns None if there is no space left in the table.

pub fn make_descriptor_available(&mut self, index: u16)

Make the descriptor chain starting at index available to the device, allowing it to start servicing the described request.

pub fn alloc_descriptor(&mut self) -> Option<u16>

pub fn free_descriptor(&mut self, index: u16)