909cce0f5d
On Redox the kernel's sys:cpu scheme is a single file (kernel/src/scheme/ sys/cpu.rs) whose contents start with 'CPUs: N\n', not a per-CPU directory. The kernel does not create /dev/cpu/ at all, so the prior read_dir-based enumeration always fell through to the single-CPU fallback on Redox — hiding the fact that the kernel had successfully brought up the APs and reporting only CPU 0 to the governor / power TUI. Read /scheme/sys/cpu and parse the 'CPUs:' line first; fall back to /dev/cpu/ for Linux hosts.