Enum AttachOutcome 

pub enum AttachOutcome {
    Attached,
    Died,
    NotAttached(String),
    Unconfirmed,
}

Whether the scheduler positively confirmed it turned on during a verifier VM run.

The guest init’s attach gate (poll_startup + poll_scx_attached in crate::vmm::rust_init::scheduler) already runs on every verifier VM boot: it confirms the scheduler process survived BPF load AND that /sys/kernel/sched_ext/state reached enabled. The kernel sets enabled only after ops.init, per-task init, and switching eligible tasks to the sched_ext class (kernel/sched/ext.c scx_root_enable_workfn), so enabled proves the scheduler turned on and is scheduling — not merely that its BPF loaded.

The verdict is POSITIVE-confirmation, not absence-of-failure: a verifier cell PASSes only when the guest reached its post-attach dispatch phase — a PayloadStarting lifecycle frame, emitted at ktstr_guest_init Phase 5, which is reached ONLY if start_scheduler succeeded in Phase 3. On attach failure the guest emits SchedulerDied / SchedulerNotAttached and force-reboots in Phase 3 BEFORE Phase 5, so no PayloadStarting arrives. A guest that vanishes before Phase 5 with NO frame at all — e.g. a kernel panic, which reboots via the guest’s panic=-1 (an i8042 reset → ExitAction::Shutdown, NOT a host watchdog timeout) — is AttachOutcome::Unconfirmed, also a FAIL. Absence-of-failure alone would false-PASS that vanish case. collect_verifier_output consumes this verdict instead of discarding it. Scheduler-agnostic (kernel sysfs state), so it holds for every declared scheduler.

Variants

Attached

The guest reached its post-attach dispatch phase (a PayloadStarting frame) with no failure frame: the scheduler loaded, stayed alive, and reached sched_ext enabled.

Died

Scheduler process exited during BPF load / startup (LifecyclePhase::SchedulerDied).

NotAttached(String)

Scheduler stayed alive but never reached enabled (LifecyclePhase::SchedulerNotAttached); carries the guest’s reason suffix when present.

Unconfirmed

No failure frame AND no PayloadStarting frame: the guest never reached the post-attach dispatch phase, so attach was never positively confirmed (e.g. an early guest kernel panic that reboots via panic=-1 before Phase 3 — emitting no lifecycle frame and NOT tripping the host watchdog).

Implementations

impl AttachOutcome

pub fn failure_reason(&self) -> Option<String>

Human-readable failure reason, or None when attached.

Trait Implementations

impl Clone for AttachOutcome

fn clone(&self) -> AttachOutcome

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AttachOutcome

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

Formats the value using the given formatter.

impl PartialEq for AttachOutcome

fn eq(&self, other: &AttachOutcome) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for AttachOutcome

impl StructuralPartialEq for AttachOutcome