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 | |