On Tue, Nov 26, 2013 at 04:58:53PM +0100, Paolo Bonzini wrote: > Il 26/11/2013 16:35, Avi Kivity ha scritto: > >>>> If we want to ensure, we need to use a different mechanism for > >>>> synchronization than the global RCU. QRCU would work; readers are not > >>>> wait-free but only if there is a concurrent synchronize_qrcu, which > >>>> should be rare. > >>> An alternative path is to convince ourselves that the hardware does not > >>> provide the guarantees that the current code provides, and so we can > >>> relax them. > >> No, I think it's a reasonable guarantee to provide. > > > > Why? > > Because IIUC the semantics may depend not just on the interrupt > controller, but also on the specific PCI device. It seems safer to > assume that at least one device/driver pair wants this to work. > > (BTW, PCI memory writes are posted, but configuration writes are not). > > Paolo You can also do a PCI read and flush out the writes. -- 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
