Halt the idle CPUs

ostd/src/arch/riscv/cpu/mod.rs

@@ -4,3 +4,17 @@
 
 pub mod context;
 pub mod local;
+
+/// Halts the CPU.
+///
+/// This function halts the CPU until the next interrupt is received. By
+/// halting, the CPU might consume less power. Internally it is implemented
+/// using the `wfi` instruction.
+///
+/// Since the function sleeps the CPU, it should not be used within an atomic
+/// mode ([`crate::task::atomic_mode`]).
+#[track_caller]
+pub fn sleep_for_interrupt() {
+    crate::task::atomic_mode::might_sleep();
+    riscv::asm::wfi();
+}