Struct devices::virtio::DescriptorChain

pub struct DescriptorChain {
    mem: GuestMemory,
    index: u16,
    pub reader: Reader,
    pub writer: Writer,
    pub id: Option<u16>,
    pub count: u16,
}

A virtio descriptor chain.

This is a low-level representation of the memory regions in a descriptor chain. Most code should use virtio::Reader and virtio::Writer rather than working with DescriptorChain memory regions directly.

Fields

mem: GuestMemory

index: u16

Index into the descriptor table.

reader: Reader

The readable memory regions that make up the descriptor chain.

writer: Writer

The writable memory regions that make up the descriptor chain.

id: Option<u16>

The descriptor chain id(only if it is a packed virtqueue descriptor chain)

count: u16

Number of descriptor in descriptor chain

Implementations

impl DescriptorChain

pub fn new( chain: impl DescriptorChainIter, mem: &GuestMemory, index: u16 ) -> Result<DescriptorChain>

Read all descriptors from chain into a new DescriptorChain instance.

This function validates the following properties of the descriptor chain:

• The chain contains at least one descriptor.
• Each descriptor has a non-zero length.
• Each descriptor’s memory falls entirely within a contiguous region of mem.
• The total length of the descriptor chain data is representable in u32.

If these properties do not hold, Err will be returned.

Arguments

• chain - Iterator that will be walked to retrieve all of the descriptors in the chain.
• mem - The GuestMemory backing the descriptor table and descriptor memory regions.
• index - The index of the first descriptor in the chain.

fn validate_mem_regions( mem: &GuestMemory, readable_regions: &[MemRegion], writable_regions: &[MemRegion] ) -> Result<()>

pub fn mem(&self) -> &GuestMemory

Returns a reference to the GuestMemory instance.

pub fn index(&self) -> u16

Returns the index of the first descriptor in the chain.