Struct DmaStream &nbsp; Copy item path

impl<D: DmaDirection> DmaStream<D>

pub fn alloc(nframes: usize, is_cache_coherent: bool) -> Result<Self, Error>

Allocates a region of physical memory for streaming DMA access.

The memory of the newly-allocated DMA buffer is initialized to zeros. This method is only available when D is ToDevice or FromAndToDevice, as zeroing requires write access to the buffer.

The is_cache_coherent argument specifies whether the target device that the DMA mapping is prepared for can access the main memory in a CPU cache coherent way or not.

§Comparison with `DmaStream::map`

This method is semantically equivalent to allocating a USegment via FrameAllocOptions::alloc_segment and then mapping it with DmaStream::map. However, DmaStream::alloc combines these two operations and can be more efficient in certain scenarios, particularly in confidential VMs, where the overhead of bounce buffers can be avoided.

pub fn alloc_uninit( nframes: usize, is_cache_coherent: bool, ) -> Result<Self, Error>

Allocates a region of physical memory for streaming DMA access without initialization.

This method is the same as DmaStream::alloc except that it skips zeroing the memory of newly-allocated DMA region.

pub fn map(segment: USegment, is_cache_coherent: bool) -> Result<Self, Error>

Establishes DMA stream mapping for a given USegment.

The is_cache_coherent argument specifies whether the target device that the DMA mapping is prepared for can access the main memory in a CPU cache coherent way or not.

pub fn sync_from_device(&self, byte_range: Range<usize>) -> Result<(), Error>

Synchronizes the streaming DMA mapping data from the device.

This method should be called when the data of the streaming DMA mapping has been updated by the device side. Before the CPU side starts to read (e.g., using read_bytes), it must call the Self::sync_from_device method first.

pub fn sync_to_device(&self, byte_range: Range<usize>) -> Result<(), Error>

Synchronizes the streaming DMA mapping data to the device.

This method should be called when the data of the streaming DMA mapping has been updated by the CPU side (e.g., using write_bytes). Before the CPU side notifies the device side to read, it must call the Self::sync_to_device method first.

Trait Implementations§

impl<D: Debug + DmaDirection> Debug for DmaStream<D>

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

Formats the value using the given formatter. Read more

impl<D: DmaDirection> Drop for DmaStream<D>

fn drop(&mut self)

Executes the destructor for this type. Read more

impl<D: DmaDirection> HasDaddr for DmaStream<D>

fn daddr(&self) -> Daddr

Returns the base address of the mapping in the device address space.

impl<D: DmaDirection> HasPaddr for DmaStream<D>

fn paddr(&self) -> Paddr

Returns the start physical address of the memory object.

impl<D: DmaDirection> HasSize for DmaStream<D>

fn size(&self) -> usize

Returns the size of the memory object in bytes.

impl<D: DmaDirection> HasVmReaderWriter for DmaStream<D>

type Types = VmReaderWriterResult

A marker type that denotes the return types of Self::reader and Self::writer. Read more

fn reader(&self) -> Result<VmReader<'_, Infallible>, Error>

Returns a reader to read data from it.

fn writer(&self) -> Result<VmWriter<'_, Infallible>, Error>

Returns a writer to write data to it.

impl<D: DmaDirection> Split for DmaStream<D>

fn split(self, offset: usize) -> (Self, Self)

Splits the memory object into two at the given byte offset from the start. Read more

Auto Trait Implementations§

impl<D = FromAndToDevice> !UnwindSafe for DmaStream<D>

Blanket Implementations§

impl<T> Any for T
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Gets the TypeId of self. Read more

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fn from(t: T) -> T

Returns the argument unchanged.

impl<T> HasPaddrRange for T
where T: HasPaddr + HasSize,

fn end_paddr(&self) -> usize

Returns the end physical address of the memory object.

fn paddr_range(&self) -> Range<usize>

Returns the physical address range of the memory object.

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Calls U::from(self).

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impl<S> VmIo for S
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fn read(&self, offset: usize, writer: &mut VmWriter<'_>) -> Result<(), Error>

Reads requested data at a specified offset into a given VmWriter. Read more

fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<(), Error>

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fn write(&self, offset: usize, reader: &mut VmReader<'_>) -> Result<(), Error>

Writes all data from a given VmReader at a specified offset. Read more

fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<(), Error>

Writes a specified number of bytes from a given buffer at a specified offset. Read more

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fn fill_zeros(&self, offset: usize, len: usize) -> Result<(), (Error, usize)>

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