On 03/21/2013 07:43 AM, Michael S. Tsirkin wrote: >> >> The reason to support this is that a guest written to only handle one or >> the other doesn't prevent the hypervisor from offering the other to >> guests. We probably want to specify that if the guest doesn't care, it >> should use the first one offered by the host. >> > > What are the configurations where having many ways is helpful? > Any examples? > In BIOS (e.g. SeaBIOS), using MMIO is very difficult, so your boot ROM probably wants to use I/O space even if MMIO is available. If you are preferring I/O space because it is faster (vmexit), then you still want to allow MMIO if the resource is not available. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
