Function sidecar_node_is_empty 

fn sidecar_node_is_empty(
    overrides: &PerCpuState,
    base_vp: usize,
    size: usize,
) -> bool

Returns true if, with per-CPU sidecar overrides active, the sidecar node whose VPs are base_vp..base_vp + size has no application processors left for sidecar to start (every AP is kernel-started).

The first VP of a node is its base VP and is always kernel-started, so sidecar only ever starts the remaining VPs.