Struct Region 

pub struct Region { /* private fields */ }

A run of FRESH pages this task was just given by AllocMem, for the §22 P7 stale-translation test.

P7 asks whether a dead task’s translations can outlive it (CLAUDE.md 10.5): a writer stamps its pages, is killed, and a checker spawned after it, given the SAME virtual addresses (every task’s AllocMem grows from one base), must read the zeroes the kernel filled its new pages with. A pattern word there means the checker read through a translation that belonged to the dead writer.

Reading and writing that memory needs a raw pointer, which a test SERVICE must not hold (18.2), so it is wrapped here. The wrapper is sound because a Region can only be made from a successful AllocMem: its pages are mapped, writable, private to this task, and referenced by nothing else - the kernel has just created them, and no Rust object lives there.

Implementations

impl Region

pub fn alloc(ctx: &ServiceContext, pages: usize) -> Option<Region>

Ask the kernel for pages fresh 4 KiB pages. None if it refused.

pub fn base(&self) -> u64

The first virtual address of the region (the same in every task that asks first).

pub fn stamp(&self, word: u32)

Write word into every 32-bit word of the region.

pub fn first_not(&self, want: u32) -> Option<(usize, u32)>

The byte offset and value of the first word that is not want, or None if every word is.