1/*
2 * Copyright (C) 2016, Emilio G. Cota <cota@braap.org>
3 *
4 * License: GNU GPL, version 2.
5 * See the COPYING file in the top-level directory.
6 */
7#ifndef QEMU_PROCESSOR_H
8#define QEMU_PROCESSOR_H
9
10#include "qemu/atomic.h"
11
12#if defined(__i386__) || defined(__x86_64__)
13# define cpu_relax() asm volatile("rep; nop" ::: "memory")
14
15#elif defined(__aarch64__)
16# define cpu_relax() asm volatile("yield" ::: "memory")
17
18#elif defined(__powerpc64__)
19/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */
20# define cpu_relax() asm volatile("or 1, 1, 1;" \
21 "or 2, 2, 2;" ::: "memory")
22
23#else
24# define cpu_relax() barrier()
25#endif
26
27#endif /* QEMU_PROCESSOR_H */
28