Function set_kernel_signal_facts 

pub const fn set_kernel_signal_facts(
    backend: &mut BackendCapabilities,
    on: bool,
)

Sets supports_blocked_wait_signal_interruption and the four capabilities Detcore read from it until A5 step 3c.0 split them out (kernel_signal_state_is_guests, kernel_signal_targets_are_predictable, host_task_reads_reach_guest_threads, host_timed_signals_are_physical) to on, together. Every backend has the five equal, so a configuration that set or cleared the one field before the split sets or clears all five with this, and behaves as it did.