diff options
Diffstat (limited to 'qemu-barrier.h')
| -rw-r--r-- | qemu-barrier.h | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/qemu-barrier.h b/qemu-barrier.h index b77fce23a9..735eea6cf9 100644 --- a/qemu-barrier.h +++ b/qemu-barrier.h @@ -1,10 +1,38 @@ #ifndef __QEMU_BARRIER_H #define __QEMU_BARRIER_H 1 -/* FIXME: arch dependant, x86 version */ -#define smp_wmb() asm volatile("" ::: "memory") - /* Compiler barrier */ #define barrier() asm volatile("" ::: "memory") +#if defined(__i386__) || defined(__x86_64__) + +/* + * Because of the strongly ordered x86 storage model, wmb() is a nop + * on x86(well, a compiler barrier only). Well, at least as long as + * qemu doesn't do accesses to write-combining memory or non-temporal + * load/stores from C code. + */ +#define smp_wmb() barrier() + +#elif defined(__powerpc__) + +/* + * We use an eieio() for a wmb() on powerpc. This assumes we don't + * need to order cacheable and non-cacheable stores with respect to + * each other + */ +#define smp_wmb() asm volatile("eieio" ::: "memory") + +#else + +/* + * For (host) platforms we don't have explicit barrier definitions + * for, we use the gcc __sync_synchronize() primitive to generate a + * full barrier. This should be safe on all platforms, though it may + * be overkill. + */ +#define smp_wmb() __sync_synchronize() + +#endif + #endif |