Thomas, Changchun,
On 29/07/2015 14:56, Thomas Monjalon wrote:
> Back on this old patch, it seems justified but nobody agreed.
>
> --- a/lib/librte_pmd_virtio/virtio_ethdev.c
> +++ b/lib/librte_pmd_virtio/virtio_ethdev.c
> @@ -1288,7 +1288,6 @@ virtio_dev_configure(struct rte_eth_dev *dev)
> && !vtpci_with_feature(hw, VIRTIO_NET_F_CTRL_VLAN)) {
> PMD_DRV_LOG(NOTICE,
> "vlan filtering not available on this host");
> - return -ENOTSUP;
> }
>
> 2015-03-06 08:24, Stephen Hemminger:
>> "Ouyang, Changchun" <changchun.ouyang at intel.com> wrote:
>>>> From: Stephen Hemminger
>>>> Vlan filtering is an option, and not a requirement.
>>>> If host does not support filtering then it can be done in software.
+1 with Stephen, remove return -ENOTSUP;
applications must not fail, software stacks will handle it. We did
experiment some issues when testpmd was failing while it was supposed to
run. A notice would be good enough.
>>>
>>> The question is that guest only send command, no real action to do the vlan
>>> filter.
>>> So if both host and guest have no real action for vlan filter, who will do
>>> it?
>>
>> The virtio driver has features.
>> Guest can not send commands to host where feature bit not enabled.
>> Application can call filter_set and check if filter worked or not.
>>
>> Our code already had to do MAC and VLAN validation of incoming packets
>> therefore if hardware can't do vlan match, there is no problem.
>> I would expect other applications would do the same thing.
>>
>> Failing during configuration is bad. DPDK API should never force
>> application to play "guess the working configuration" with the device
>> driver or do string match on "which device is this anyway"
Agree, it is not a failure of a configuration, it is a failure of
negotiation of virtio's capabilities.
Let's use another example: we do not expect a guest kernel to panic()
because it is not properly negotiated? So why should a DPDK application
fail and return -ENOTSUP?
Thank you,
Vincent
