Struct ArenaSnapshot 

#[non_exhaustive]
pub struct ArenaSnapshot {
    pub pages: Vec<ArenaPage>,
    pub truncated: bool,
    pub declared_pages: u64,
    pub span_capped: bool,
    pub kern_vm_start: u64,
    pub user_vm_start: u64,
}

Snapshot of one arena map’s mapped pages.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

pages: Vec<ArenaPage>

Mapped pages, in pgoff order (skipped over unmapped pgoffs). Sequential prefix (pgoffs 0..MAX_ARENA_PAGES) followed by any stride-probe hits in the sparse tail (pgoffs sampled across MAX_ARENA_PAGES..declared_pages).

truncated: bool

True when the walker stopped sequential enumeration at MAX_ARENA_PAGES before finishing the user_vm window. The stride sweep that follows samples the tail at coarse intervals, so a hit reaches pages even when this flag is set; pgoffs between sampled positions are still silently skipped.

declared_pages: u64

Total declared page count. Derived from max_entries * page_size (the BPF map’s declared page capacity, with page_size resolved from the guest’s TCR_EL1 via guest_page_size), not the user_vm window. Reflects any MAX_VM_RANGE_BYTES cap. Surfaced alongside pages.len() so consumers can see the allocated-vs-declared ratio.

span_capped: bool

True when max_entries * page_size exceeded MAX_VM_RANGE_BYTES (4 GiB) and the walker capped the span before computing declared_pages. Indicates a torn / corrupt bpf_arena struct or a freeze-time race against initialization; the rendered pages still come from valid translates, so the snapshot is usable.

kern_vm_start: u64

Kernel-side base of the arena’s user_vm window: bpf_arena.kern_vm->addr + GUARD_HALF. Surfaces here so downstream consumers (notably the super::sdt_alloc tree walker) can translate __arena pointers without re-reading struct bpf_arena themselves. 0 when the snapshot bailed before computing the value (kern_vm_kva NULL, vm_addr NULL, or any of the upstream translates failed).

Always serialized — the zero value carries diagnostic information (“walker reached this point but couldn’t compute the base”), so suppressing it would mask the failure. Mirrors the policy used for the sibling declared_pages field.

user_vm_start: u64

User-side base of the arena window: the value of bpf_arena.user_vm_start, the address space the BPF program (and any captured __arena pointer) sees. [user_vm_start .. user_vm_start + 4 GiB) is the kernel-enforced upper bound (bpf_arena_alloc_pages clamps to SZ_4G). Consumers use it to classify a pointer as “lives in this arena” before chasing into Self::pages.

0 when the snapshot bailed before reading arena.user_vm_start (e.g. arena_pa translate failed). On the syscall backend this comes from bpf_map.map_extra which the kernel pins at create time (lib/arena_map.h hardcodes 1<<44 on x86, 1<<32 on aarch64). On the guest-memory backend it’s read directly from bpf_arena.user_vm_start via the resolved offset.

Always serialized for the same diagnostic reason as Self::kern_vm_start.

Trait Implementations

impl Clone for ArenaSnapshot

fn clone(&self) -> ArenaSnapshot

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ArenaSnapshot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ArenaSnapshot

fn default() -> ArenaSnapshot

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ArenaSnapshot

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ArenaSnapshot

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.