Crate ruvix_physmem 

RuVix Physical Memory Allocator

This crate provides a buddy allocator for physical page frame allocation as part of the RuVix Cognition Kernel (ADR-087).

Overview

The buddy allocator manages physical memory using power-of-two block sizes, enabling efficient allocation and deallocation with minimal fragmentation. It supports block sizes from 4KB (single page) to 2MB (512 pages).

Architecture

+------------------+
| BuddyAllocator   |
|------------------|
| free_lists[10]   | <- One list per order (0-9)
| base_addr        | <- Start of managed memory
| total_pages      | <- Total pages under management
| stats            | <- Allocation statistics
+------------------+
         |
         v
+------------------+
| Free Lists       |
|------------------|
| Order 0: 4KB     | <- Single pages
| Order 1: 8KB     | <- 2 pages
| Order 2: 16KB    | <- 4 pages
| ...              |
| Order 9: 2MB     | <- 512 pages
+------------------+

Features

• std: Enable standard library support
• alloc: Enable alloc crate support
• stats: Enable detailed statistics collection
• debug-alloc: Enable debug assertions for allocation tracking

Example

use ruvix_physmem::{BuddyAllocator, PhysAddr, PAGE_SIZE};

// Create allocator for 16MB of memory starting at physical address 0x1000_0000
let mut allocator = BuddyAllocator::new(PhysAddr::new(0x1000_0000), 4096);

// Allocate 4 contiguous pages (16KB)
if let Some(addr) = allocator.alloc_pages(4) {
    // Use the memory...
    allocator.dealloc_pages(addr, 4);
}

Structs

AllocatorStats

Statistics for the buddy allocator.

BuddyAllocator

A buddy allocator for physical page frames.

PageFrame

A physical page frame.

PageOrder

The order of a page frame block.

PhysAddr

A physical memory address.

Enums

KernelError

Kernel error codes.

PhysMemError

Physical memory allocator errors.

Constants

MAX_BLOCK_PAGES

Maximum block size in pages (2^(MAX_ORDER-1) = 512 pages).

MAX_BLOCK_SIZE

Maximum block size in bytes (2MB).

MAX_ORDER

Maximum order for buddy allocation (2^9 = 512 pages = 2MB).

MIN_ORDER

Minimum allocation unit (single page).

PAGE_SHIFT

Page size shift (log2(PAGE_SIZE)).

PAGE_SIZE

Page size in bytes (4KB).

Functions

align_down

Aligns an address down to the nearest page boundary.

align_up

Aligns an address up to the nearest page boundary.

is_page_aligned

Checks if an address is page-aligned.

order_to_bytes

Calculates the block size in bytes for a given order.

order_to_pages

Calculates the number of pages for a given order.

pages_to_order

Calculates the order required for a given number of pages.