Module frame

Frame (physical memory page) management.

A frame is an aligned, contiguous range of bytes in physical memory. The sizes of base frames and huge frames (that are mapped as “huge pages”) are architecture-dependent. A frame can be mapped to virtual address spaces using the page table.

Frames can be accessed through frame handles, namely, Frame. A frame handle is a reference-counted pointer to a frame. When all handles to a frame are dropped, the frame is released and can be reused. Contiguous frames are managed with Segment.

There are various kinds of frames. The top-level grouping of frame kinds are “typed” frames and “untyped” frames. Typed frames host Rust objects that must follow the visibility, lifetime and borrow rules of Rust, thus not being able to be directly manipulated. Untyped frames are raw memory that can be manipulated directly. So only untyped frames can be

• safely shared to external entities such as device drivers or user-space applications.
• or directly manipulated with readers and writers that neglect Rust’s “alias XOR mutability” rule.

The kind of a frame is determined by the type of its metadata. Untyped frames have its metadata type that implements the AnyUFrameMeta trait, while typed frames don’t.

Frames can have dedicated metadata, which is implemented in the meta module. The reference count and usage of a frame are stored in the metadata as well, leaving the handle only a pointer to the metadata slot. Users can create custom metadata types by implementing the AnyFrameMeta trait.

Re-exports

pub use allocator::GlobalFrameAllocator;

pub use segment::Segment;

Modules

allocator

The physical memory allocator.

frame_ref 🔒

linked_list

Enabling linked lists of frames without heap allocation.

meta

Metadata management of frames.

segment

A contiguous range of frames.

unique

The unique frame pointer that is not shared with others.

untyped

Untyped physical memory management.

Structs

Frame

A smart pointer to a frame.

FrameRef

A struct that can work as &'a Frame<M>.

Statics

MAX_PADDR 🔒

Functions

inc_frame_ref_count 🔒 ^⚠

Increases the reference count of the frame by one. For a frame derived from paddr

max_paddr 🔒

Returns the maximum physical address that is tracked by frame metadata.