[qemu.git] / include / qemu / processor.h

/*
 * Copyright (C) 2016, Emilio G. Cota <[email protected]>
 *
 * License: GNU GPL, version 2.
 *   See the COPYING file in the top-level directory.
 */
#ifndef QEMU_PROCESSOR_H
#define QEMU_PROCESSOR_H

#include "qemu/atomic.h"

#if defined(__i386__) || defined(__x86_64__)
# define cpu_relax() asm volatile("rep; nop" ::: "memory")

#elif defined(__aarch64__)
# define cpu_relax() asm volatile("yield" ::: "memory")

#elif defined(__powerpc64__)
/* set Hardware Multi-Threading (HMT) priority to low; then back to medium */
# define cpu_relax() asm volatile("or 1, 1, 1;" \
                                  "or 2, 2, 2;" ::: "memory")

#else
# define cpu_relax() barrier()
#endif

#endif /* QEMU_PROCESSOR_H */
Commit	Line	Data
462cda50 EC	1	/*
	2	* Copyright (C) 2016, Emilio G. Cota <[email protected]>
	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
462cda50 EC	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 */