Le 20/04/2016 01:07, Emilio G. Cota a écrit :
Taken from the linux kernel.
Reviewed-by: Richard Henderson <r...@twiddle.net>
Signed-off-by: Emilio G. Cota <c...@braap.org>
---
include/qemu/processor.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
create mode 100644 include/qemu/processor.h
diff --git a/include/qemu/processor.h b/include/qemu/processor.h
new file mode 100644
index 0000000..675a00a
--- /dev/null
+++ b/include/qemu/processor.h
@@ -0,0 +1,28 @@
Hi,
Does this file need a license?
Fred
+#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")
+#endif
+
+#ifdef __ia64__
+#define cpu_relax() asm volatile("hint @pause" ::: "memory")
+#endif
+
+#ifdef __aarch64__
+#define cpu_relax() asm volatile("yield" ::: "memory")
+#endif
+
+#if 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")
+#endif
+
+#ifndef cpu_relax
+#define cpu_relax() barrier()
+#endif
+
+#endif /* QEMU_PROCESSOR_H */
