LXR qemu/include/qemu/processor.h

   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