Struct BuddyAllocator 

pub struct BuddyAllocator<const TOTAL_PAGES: usize, const BITMAP_WORDS: usize> { /* private fields */ }

A buddy allocator managing TOTAL_PAGES of physical memory.

The allocator is entirely stack-allocated with a fixed-size bitmap. TOTAL_PAGES must be a power of two and at most 2^MAX_ORDER * some_count.

Type Parameters

• TOTAL_PAGES: The total number of 4 KiB pages managed. Must be a power of two.
• BITMAP_WORDS: The number of u64 words in the bitmap. Must be at least total_bitmap_bits(TOTAL_PAGES) / 64 + 1. Use BuddyAllocator::REQUIRED_BITMAP_WORDS to compute this.

Implementations

impl<const TOTAL_PAGES: usize, const BITMAP_WORDS: usize> BuddyAllocator<TOTAL_PAGES, BITMAP_WORDS>

pub const REQUIRED_BITMAP_WORDS: usize

The number of bitmap u64 words required for TOTAL_PAGES.

pub fn new(base: PhysAddr) -> RvmResult<Self>

Create a new buddy allocator managing memory starting at base.

All blocks are initially marked as free. base must be page-aligned.

Errors

Returns RvmError::AlignmentError if base is not page-aligned. Returns RvmError::ResourceLimitExceeded if BITMAP_WORDS is insufficient.

pub fn alloc_pages(&mut self, order: usize) -> RvmResult<PhysAddr>

Allocate 2^order contiguous pages.

Returns the base PhysAddr of the allocated block.

Uses trailing_zeros on bitmap words for fast first-free-block scanning: O(1) per 64-bit word instead of checking bit-by-bit.

Errors

Returns RvmError::OutOfMemory if no block of the requested size is available.

pub fn free_pages(&mut self, addr: PhysAddr, order: usize) -> RvmResult<()>

Free a previously allocated block of 2^order pages starting at addr.

The caller must ensure addr was returned by a prior alloc_pages(order) call.

Errors

Returns RvmError::AlignmentError if the address is invalid or misaligned. Returns RvmError::InvalidTierTransition if the order exceeds the maximum. Returns RvmError::InternalError on double-free detection.

pub fn free_page_count(&self) -> usize

Return the total number of free pages across all orders.