Hi Thoms > -----Original Message----- > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > Sent: Friday, September 23, 2016 2:15 PM > To: Richardson, Bruce <bruce.richardson at intel.com>; Iremonger, Bernard > <bernard.iremonger at intel.com> > Cc: dev at dpdk.org; Jerin Jacob <jerin.jacob at caviumnetworks.com>; Shah, > Rahul R <rahul.r.shah at intel.com>; Lu, Wenzhuo <wenzhuo.lu at intel.com>; > azelezniak <alexz at att.com> > Subject: Re: [dpdk-dev] [RFC PATCH v2 3/5] librte_ether: add API's for VF > management > > 2016-09-23 09:53, Richardson, Bruce: > > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > > > 2016-09-23 10:20, Bruce Richardson: > > > > On Thu, Sep 22, 2016 at 07:04:37PM +0200, Thomas Monjalon wrote: > > > > > 2016-09-15 16:46, Iremonger, Bernard: > > > > > > > > > Do we really need to expose VF specific functions here? > > > > > > > > > It can be generic(PF/VF) function indexed only through > > > port_id. > > > > > > > > > (example: as rte_eth_dev_set_vlan_anti_spoof(uint8_t > > > > > > > > > port_id, uint8_t on)) For instance, In Thunderx PMD, We > > > > > > > > > are not exposing a separate port_id for PF. We only > > > > > > > > > enumerate 0..N VFs as 0..N ethdev port_id > > > > > > > > > > > > > > > > Our intention with this patch is to control the VF from the PF. > > > > > > > > > > > > > > > > The following librte_ether functions already work in a > > > > > > > > similar > > > way: > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_rxmode(uint8_t port_id, uint16_t vf, > > > > > > > > uint16_t rx_mode, uint8_t on) > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_rx(uint8_t port_id, uint16_t vf, > > > > > > > > uint8_t > > > > > > > > on) > > > > > > > > > > > > > > > > rte_eth_dev_set_vf_tx(uint8_t port_id, uint16_t vf, > > > > > > > > uint8_t > > > > > > > > on) > > > > > > > > > > > > > > > > int rte_eth_set_vf_rate_limit(uint8_t port_id, uint16_t > > > > > > > > vf, uint16_t tx_rate, uint64_t q_msk) > > > > > > > > > > > > > > I have a bad feeling with these functions dedicated to VF from PF. > > > > > > > Are we sure there is no other way? > > > > > > > I mean we just need to know the VF with a port ID. > > > > > > > > > > > > When the VF is used in a VM the port ID of the VF is not > > > > > > visible to > > > the PF. > > > > > > I don't think there is another way to do this. > > > > > > > > > > I don't understand why we could not assign a port id to the VF > > > > > from the host instead of having the couple PF port id / VF id. > > > > > Can we enumerate all the VFs associated to a PF? > > > > > Then can we allocate them a port id in the array rte_eth_devices? > > > > > > > > Hi Thomas, > > > > > > > > The VF is not a port visible to DPDK, though, so it shouldn't have > > > > a port id IMHO. DPDK can't actually do anything with it. > > > > > > You say the contrary below. > > > > Well, yes and no. The driver can manipulate things for the VF, but DPDK > doesn't actually have a device that corresponds to the VF. There are no PCI > bar mappings for it, DPDK can't do RX and TX with it etc.? > > Very good point. > There are only few ethdev functions which are supported by every drivers, > like Rx/Tx and would not be available for VF from PF interface. > > > > > The PCI device for the VF is likely passed through to a different > > > > VM and being used there. Unfortunately, the VF still needs certain > > > > things done for it by the PF, so if the PF is under DPDK control, > > > > it needs to provide the functionality to assist the VF. > > > > > > Why not have a VF_from_PF driver which does the mailbox things? > > > So you can manage the VF from the PF with a simple port id. > > > It really seems to be the cleanest design to me. > > > > While I see your point, and it could work, I just want to be sure that we > > are > ok with the results of that. Suppose we do create ethdevs for the VFs > controlled by the PF. Does the new VF get counted in the > rte_eth_dev_count() value (I assume yes)? How are apps meant to use the > port? Do they have to put in a special case when iterating through all the > port > ids to check that it's not a pseudo port that can't do anything. None of the > standard ethdev calls from an app will work on it, you can't configure nb > rx/tx > queues on it, you can't start or stop it, you can't do rx or tx on it, etc, > etc. > > Yes these devices would be special because their supported API would be > quite different. I was thinking that in the future you could add most of the > configuration functions through the VF mailbox. > But the Intel mailbox currently support only some special configurations > which are not supported by other devices even its own VF device (except > setting MAC address). > And when I read "set drop enable bit in the VF split rx control register", it > becomes clear it is really specific and has nothing to do in the generic > ethdev > API. > That's why it is a NACK. > > When we want to use these very specific features we are aware of the > underlying device and driver. So we can directly include a header from the > driver. I suggest to retrieve a handler for the device which is not a port id > and > will allow to call ixgbe functions directly. > It could be achieved by adding an ethdev function like discussed here: > http://dpdk.org/ml/archives/dev/2016-September/047392.html >
I have been reading the net/vhost mail thread above. The following quote is from this thread. "It means I would be in favor of introducing API in drivers for very specific features." At present all the PMD functions are accessed through the eth_dev_ops structure, there are no PMD API's. Is your proposal to add API(s) to the DPDK ixgbe PMD (similar to a driver ioctl API) which can be accessed through a generic API in the ethdev? What will this generic API look like? Regards, Bernard.
