Anthony Liguori wrote: > Avi Kivity wrote: >> Anthony Liguori wrote: >> >>> + case VIRTIO_PCI_QUEUE_NOTIFY: >>> + if (val < VIRTIO_PCI_QUEUE_MAX) >>> + virtio_ring_kick(vdev, &vdev->vq[val]); >>> + break; >>> >> >> I see you're not using hypercalls for this, presumably for compatibility >> with -no-kvm. > > More than just that. By stick to PIO, we are compatible with just > about any VMM. For instance, we get Xen support for free. If we used > hypercalls, even if we agreed on a way to determine which number to > use and how to make those calls, it would still be difficult to > implement in something like Xen. >
But pio through the config space basically means you're committed to handling it in qemu. We want a more flexible mechanism. Detecting how to make hypercalls can be left to paravirt_ops. (for Xen you'd use an event channel; and for kvm the virtio kick hypercall). >> Well I think I have a solution: advertise vmcall, >> vmmcall, pio to some port, and int $some_vector as hypercall feature >> bits in cpuid (for kvm, kvm, qemu, and kvm-lite respectively). Early >> setup code could patch the instruction as appropriate (I hear code >> patching is now taught in second grade). >> > > That ties our device to our particular hypercall implementation. If > we were going to do this, I'd prefer to advertise it in the device I > think. I really would need to look at the performance though of > vmcall and an edge triggered interrupt. It would have to be pretty > compelling to warrant the additional complexity I think. vmcall costs will go down, and we don't want to use different mechanisms for high bandwidth and low bandwidth devices. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
