2016-11-28 16:28, Maxime Coquelin: > On 11/24/2016 04:24 PM, Kavanagh, Mark B wrote: > > DPDK v16.04 added support for vHost User TSO; as such, by default, > > TSO is advertised to guest devices as an available feature during > > feature negotiation with QEMU. > > However, while the vHost user backend sets up the majority of the > > mbuf fields that are required for TSO, there is still a reliance > > on the associated DPDK application (i.e. in this case OvS-DPDK) > > to set the remaining flags and/or offsets. > > Since OvS-DPDK doesn't currently provide that functionality, it is > > necessary to explicitly disable TSO; otherwise, undefined behaviour > > will ensue. > > Thanks Mark for the clarification. > > In this case, maybe we could add a DPDK build option to disable Vhost's > TSO support, that would be selected for OVS packages?
Why do you prefer a build-time option rather than the run-time config with rte_vhost_feature_disable()? Because we need to lock the features? Reminder: build-time configuration options are forbidden in DPDK for such usage. It would prevent other applications from using the feature in a given distribution, just because it is not implemented in OVS. > Does that sound reasonable? Maybe I'm missing something but I feel it is more reasonnable to implement the missing code in OVS. If something is missing in DPDK, do not hesitate to request or add more helper functions.
