Re: [libvirt] qemu: hotplug virtio_scsi over lsilogic when sicsi controller is not present?

On Tue, Jul 11, 2017 at 03:47:55PM -0400, Liang Yan wrote: > Hi, > > We hit some problems when we attached some lun devices in our vm, turns > out that libvirt created lsilogic scsi controller automatically for > these scsi devices, however these device works well under virtio_scsi > controller. > > the current code logic is check lsilogic first, if qemu could not > support it, then check virtio_scsi, however is it better to check > virtio_scsi earlier? since it is supported better in qemu level? > It is not in older QEMUs which we need to stay compatible with.

> I am wondering which solution is better? > 1. simple switch sequence and check virtio_scsi first > We can't do that. We have to keep parsing older XMLs (that did not have the model in them) the same way as we were before so that we keep stable guest ABI. > 2. add extra option for "virsh attach-disk" to choose specific > controller type > Or you can first attach the controller and then attach-device with the xml that specifies that particular controller. attach-disk is a syntactic sugar for attach-device IIRC.

> Thanks, > Liang > > > ==================================== > Code part is like below > > qemu_hotplug.c qemuDomainFindOrCreateSCSIDiskController > > /* No SCSI controller present, for backward compatibility we > * now hotplug a controller */ > if (VIR_ALLOC(cont) < 0) > return NULL; > cont->type = VIR_DOMAIN_CONTROLLER_TYPE_SCSI; > cont->idx = controller; > cont->model = -1; > > VIR_INFO("No SCSI controller present, hotplugging one"); > if (qemuDomainAttachControllerDevice(driver, > > > > qemu_domain_address.c qemuDomainSetSCSIControllerModel > > if (qemuDomainIsPSeries(def)) { > *model = VIR_DOMAIN_CONTROLLER_MODEL_SCSI_IBMVSCSI; > } else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_SCSI_LSI)) { > *model = VIR_DOMAIN_CONTROLLER_MODEL_SCSI_LSILOGIC; > } else if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_SCSI)) { > *model = VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI; > } else { > virReportError(VIR_ERR_INTERNAL_ERROR, "%s", > _("Unable to determine model for scsi > controller")); > return -1; > > > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list