On Fri, Sep 23, 2016 at 09:23:11PM +0000, Wiles, Keith wrote: > > Regards, > Keith > > > On Sep 23, 2016, at 12:26 AM, Yuanhan Liu <yuanhan.liu at linux.intel.com> > > wrote: > > > > On Thu, Sep 22, 2016 at 06:43:55PM +0200, Thomas Monjalon wrote: > >>>>>>>> There could be a similar need in other PMD. > >>>>>>>> If we can get an opaque identifier of the device which is not the > >>>>>>>> port id, > >>>>>>>> we could call some specific functions of the driver not implemented > >>>>>>>> in > >>>>>>>> the generic ethdev API. > >>>>>>> > >>>>>>> That means you have to add/export the PMD API first. Isn't it against > >>>>>>> what > >>>>>>> you are proposing -- "I think we should not add any API to the PMDs" > >>>>>>> ;) > >>>>>> > >>>>>> Yes you are totally right :) > >>>>>> Except that in vhost case, we would not have any API in the PMD. > >>>>>> But it would allow to have some specific API in other PMDs for the > >>>>>> features > >>>>>> which do not fit in a generic API. > >>>>> > >>>>> So, does that mean you are okay with this patch now? I mean, okay to > >>>>> introduce > >>>>> a vhost PMD API? > >>>> > >>>> It means I would be in favor of introducing API in drivers for very > >>>> specific > >>>> features. > >>>> In this case, I am not sure that retrieving an internal id is very > >>>> specific. > >>> > >>> It's not, instead, it's very generic. The "internal id" is actually the > >>> public interface to vhost-user application, like "fd" to file APIs. > >>> > >>> Instead of introducing a few specific wrappers/APIs, I'd prefer to > >>> introduce a generic one to get the handle, and let the application to > >>> call other vhost APIs. > >> > >> Yes it makes sense. > >> I was thinking of introducing a function to get an internal id from ethdev, > >> in order to use it with any driver or underlying library. > >> But it would be an opaque pointer and you need an int. > >> Note that we can cast an int into a pointer, so I am not sure what is best. > > > > Yes, that should work. But I just doubt what the "opaque pointer" could be > > for other PMD drivers, and what the application could do with it. For a > > typical nic PMD driver, I can think of nothing is valuable to export to > > user applications. > > > > But maybe it's valuable to other virtual PMD drives as well, like the TAP > > pmd from Keith? > > I do not see a need in the TAP PMD other then returning the FD for TUN/TAP > device.
Yes, that's what I meant. > Not sure what any application would need with the FD here, as it could cause > some problems. Me, neither. > This feels like we are talking about a IOCTL like generic interface into the > PMD. Then we can add new one types and reject types in the PMD that are not > supported. Would this not be a better method for all future PMD APIs? > > Here is just a thought as to how to solve this problem without a PMD specific > API. A number of current ethdev APIs could be removed to use the API below. > The APIs would be removed from ethdev structure and have the current APIs use > the API below. I know some are not happy with number of APIs in the ethdev > structure. > > The API could be something like this: > struct rte_tlv { /* Type/Length/Value like structure */ > uint16_t type; /* Type of command */ > uint16_t len; /* Length of data section on input and on output */ > uint16_t tlen; /* Total or max length of data buffer */ > uint8_t data[0]; > }; > > int rte_eth_dev_ioctl(int pid, int qid, struct rte_tlv *tlv); Looks like a very clean solution to me! Thomas? --yliu > > > > > If so, we may go that way. > > > > Another thought is that, it may be a bit weird to me to introduce an API > > to get an opaque pointer. I mean, it's a bit hard to document it, because > > it has different meaning for different drivers. Should we list all of > > them then? > > > > --yliu