From: "Wiles, Keith" <keith.wiles@intel.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: Thomas Monjalon <thomas.monjalon@6wind.com>,
"Loftus, Ciara" <ciara.loftus@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH] net/vhost: Add function to retreive the 'vid' for a given port id
Date: Fri, 23 Sep 2016 21:23:11 +0000 [thread overview]
Message-ID: <A7E0C46D-F68F-497E-BD7C-82EDBF20F084@intel.com> (raw)
In-Reply-To: <20160923042641.GP23158@yliu-dev.sh.intel.com>
Regards,
Keith
> On Sep 23, 2016, at 12:26 AM, Yuanhan Liu <yuanhan.liu@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. Not sure what any application would need with the FD here, as it could cause some problems.
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);
>
> 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
next prev parent reply other threads:[~2016-09-23 21:23 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 13:47 Ciara Loftus
2016-09-13 15:10 ` Thomas Monjalon
2016-09-14 4:43 ` Yuanhan Liu
2016-09-14 7:10 ` Thomas Monjalon
2016-09-14 7:21 ` Yuanhan Liu
2016-09-14 8:35 ` Thomas Monjalon
2016-09-18 8:27 ` Yuanhan Liu
2016-09-21 13:07 ` Thomas Monjalon
2016-09-22 2:36 ` Yuanhan Liu
2016-09-22 16:43 ` Thomas Monjalon
2016-09-23 4:26 ` Yuanhan Liu
2016-09-23 8:43 ` Thomas Monjalon
2016-09-23 9:16 ` Yuanhan Liu
2016-09-23 9:26 ` Loftus, Ciara
2016-09-23 21:23 ` Wiles, Keith [this message]
2016-09-26 3:19 ` Yuanhan Liu
2016-09-26 13:12 ` Thomas Monjalon
2016-09-26 13:18 ` Bruce Richardson
2016-09-26 14:26 ` Thomas Monjalon
2016-09-26 14:34 ` Bruce Richardson
2016-09-26 16:24 ` Iremonger, Bernard
2016-09-26 16:55 ` Thomas Monjalon
2016-09-26 17:05 ` Wiles, Keith
2016-09-28 16:59 ` Mcnamara, John
2016-09-29 9:21 ` Mcnamara, John
2016-09-29 9:30 ` Thomas Monjalon
2016-09-29 12:08 ` Yuanhan Liu
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