在 2013-8-18，22:07，Paolo Bonzini <pbonzini@xxxxxxxxxx> 写道： > Il 15/08/2013 09:59, Arthur Chunqi Li ha scritto: >>>> volatile u32 stage? And we have barrier() to avoid reordering. >> Reordering here is not a big deal here, though it is actually needed >> here. I occurred the following problem: >> >> stage = 1; >> do something that causes vmexit; >> stage = 2; >> >> Then the compiler will optimize "stage = 1" and "stage = 2" to one >> instruction "stage =2", since instructions between them don't use >> "stage". Can volatile solve this problem? > > I'm not sure if volatile stores are reordered against non-volatile stores. > > Better keep set_stage() but write it as > > barrier(); > stage = s; > barrier(); Yep. I have done it like this in the 2nd version. Arthur > > Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
