Struct Folio

pub struct Folio { /* private fields */ }

The ownership of a contiguous page-aliged memory region.

To summarize:

• The memory block address is page-aligned (typically 4KB).
• The memory block size is also page-aligned.
• The memory block is physically contiguous.

When to use

Use folio when you need a physically contiguous memory region. The common case is when you need to allocate a DMA buffer in a device driver (strictly speaking, when IOMMU is not available).

Prefer Box<T> over folio

Unless you need low-level control over memory allocation, use containers like Vec<T> or Box<T> memory regions directly, such as DMA buffers, MMIO regions, and shared instead of folio. Folio is intended for OS services that need to manage memory between processes.

You may want MappedFolio instead

If you want to access the memory region, use MappedFolio instead.

Why “folio”?

Because it’s a sheet of paper (pages).

Implementations

impl Folio

pub fn create(len: usize) -> Result<Folio, FtlError>

pub fn handle(&self) -> &OwnedHandle

pub fn paddr(&self) -> Result<PAddr, FtlError>