Struct BitmapFrameAlloc 

pub struct BitmapFrameAlloc {
    bitmap: [u64; 256],
    base: u64,
}

Minimal bitmap-based PMM for 4K frames in a fixed region.

This type manages a fixed region of physical memory, tracking free/used 4K frames using a bitmap. It supports allocation and freeing, but does not require a heap.

Example

use kernel_alloc::frame_alloc::BitmapFrameAlloc;
use kernel_vmem::FrameAlloc;
let mut pmm = BitmapFrameAlloc::new();
let frame = pmm.alloc_4k();
if let Some(pa) = frame {
    // Use the physical address...
    pmm.free_4k(pa);
}

Safety

• Only physical addresses within the managed region are tracked.
• The user must ensure that reserved/used frames (e.g., kernel, bootloader) are marked as used before allocation.
• No synchronization is provided; not thread-safe.

Fields

bitmap: [u64; 256]

base: u64

Implementations

impl BitmapFrameAlloc

pub const fn new() -> Self

pub const fn mark_used(&mut self, frame_idx: usize)

Mark a frame as used (allocated).

pub const fn mark_free(&mut self, frame_idx: usize)

Mark a frame as free.

pub const fn is_used(&self, frame_idx: usize) -> bool

Returns true if the frame is allocated.

Trait Implementations

impl Default for BitmapFrameAlloc

fn default() -> Self

Returns the “default value” for a type.

impl FrameAlloc for BitmapFrameAlloc

fn alloc_4k(&mut self) -> Option<PhysicalPage<Size4K>>

Allocate a zeroed 4 KiB page suitable for a page-table.

fn free_4k(&mut self, pa: PhysicalPage<Size4K>)

Deallocate a zeroed 4 KiB page suitable for a page-table.