Struct VirtioBufferRef 

pub struct VirtioBufferRef<'a> { /* private fields */ }

Describes a buffer that can be submitted to a virtio queue.

A buffer describes the memory used by a virtio device to read the input and write the output for a task. The description is a list of VirtioMemoryRange. Each memory range must be contiguous in the PCI device’s addressable space.

The driver submits a buffer to ask the virtio device to perform a task. Submitting a buffer transfers the driver’s ownership of the buffer to the device. The device returns the buffer when it completes the task. Returning the buffer transfers ownership back to the driver.

For convenience, we say that a buffer is submitted when it is owned by the device. We also say that a memory range is submitted when the buffer that it belongs to is submitted. The device may only access the memory submitted buffers, which are the buffers that it owns.

The list of memory regions must first contain the regions storing the task’s input (using VirtioMemoryRangeAccess::Input), followed by the regions storing the task’s output (using VirtioMemoryRangeAccess::Output).

Implementations

impl<'a> VirtioBufferRef<'a>

pub const MAX_LENGTH: usize = 32768

The maximum number of contiguous memory regions in a buffer.

The upper bound is based on the fact that a buffer’s memory regions must fit in a virtqueue’s descriptor table, so the number of memory regions is capped by the virtqueue descriptor table size.

pub fn new(range_list: &'a [VirtioMemoryRange]) -> VirtioBufferRef<'a>

Panics if the list of ranges is empty, or if a range with VirtioMemoryRangeAccess::Input access follows a range with VirtioMemoryRangeAccess::Output access.

pub fn len(&self) -> NonZero<u16>

Returns the number of memory ranges in the buffer.

Trait Implementations

impl<'a> AsRef<[VirtioMemoryRange]> for VirtioBufferRef<'a>

fn as_ref(&self) -> &[VirtioMemoryRange]

Converts this type into a shared reference of the (usually inferred) input type.