[dpdk-dev] [PATCH v5 0/9] ethdev: support SubFunction representor

[Andrew Rybchenko]

On 2/4/21 5:15 PM, Xueming(Steven) Li wrote:
> 
>> -----Original Message-----
>> From: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>
>> Sent: Monday, February 1, 2021 4:39 PM
>> To: Xueming(Steven) Li <xuemingl at nvidia.com>
>> Cc: dev at dpdk.org; Slava Ovsiienko <viacheslavo at nvidia.com>; Asaf Penso <asafp at nvidia.com>
>> Subject: Re: [dpdk-dev] [PATCH v5 0/9] ethdev: support SubFunction representor
>>
>> On 1/28/21 5:31 PM, Xueming(Steven) Li wrote:
>>> <snip>
>>>>> The patch of device SF capability, but seems I misunderstood your suggestion.
>>>>> Let me explain process to create a SF:
>>>>> 1. SF can be created on the fly with scripts, unlike VF which is statically pre-created.
>>>>
>>>> Is there a maximum index and maximum total number of SF's created? How to find it?
>>>
>>> The maximum index is defined by firmware configuration, all SF's
>>> information could be found from sysfs. To create a SF, both PCI and sfnum have to be specified.
>>
>> sysfs is obviously Linux specific. I think the information should be available via DPDK API.
> 
> Yes, the new api discussed below should resolve this issue.
> 
>>
>>>>
>>>>> 2. SF is created on a PF with a SF number. SF number is named per PF, different PF may have same SF number.
>>>>> 3. For standalone PF, hot plug to DPDK using "PF#_BDF,representor=sf#", no need to use pf#sf# here.
>>>>> 4. For bonding netdev, hot plug to DPDK using "PF0_BDF,representor=pf#sf#"
>>>>> If using new api to return all representor IDs, need some way locate
>>>>> the new created SF by PF and SF number, that's why "pf#sf#" is used in this patch set.
>>>>
>>>> I think the API should simply reserve/report space for maximum number
>>>> of SFs. So, IDs are stable across restart/reboot in assumption that NIC is not reconfigured (changed maximum number of VF or
>> maximum number of SFs of any PF).
>>>
>>> Yes, IDs should be stable as long as no  NIC firmware configuration change.
>>>
>>> Just clarify, this api should be common enough to report all devices that a bus device supports:
>>> 1. name, might contains controller and pf info, example: "eth:representor:c0pf1vf"
>>> 2. ID range, example: 0-127
>>> The api describes ID ranges for each sub device type, users have to query the api and choose representor ID to probe.
>>>
>>> Prototype:
>>> struct rte_bus_device_range {
>>> 	char name[64];
>>> 	uint32_t base;
>>> 	uint32_t number;
>>> }
>>> /* return number of ranges filled, or number of ranges if list is
>>> NULL. */ int rte_bus_ dev_range_get(struct rte_bus_device_range *list,
>>> int n);
>>
>> Hm, I thought about more port representor specific API.
>> For me it is hard to tell if such generic naming is good or bad. I think it should be proven that such generic API makes sense. Any other
>> potential users / use cases?
> 
> I was thinking about SF, but SF is PCI specific, not suitable for this api. So I'm fine to make it as ethdev api.
> To append new api into eth_dev_ops, is there ABI concern?

No, eth_dev_ops are internal

>> I've considered ethdev API which returns (in similar way as
>> above) list of possible port representors which could be controlled by the device. Also I think it would be useful to include type
>> information (enum with PF, VF, SF), controller ID.
> 
> Agree. 
> 
> There is a new concern from orchestration side, currently, no interface in openstack and OVS to retrieve representor ID range info,
> It will take time to adapt this solution. To probe a representor, orchestration need to know how to calculate representor ID, 
> and the ID might vary on different max SF number, i.e. VF4 on PP1 might got different ID. Representor ID change before that will
> break the product.

I see.

> Considering both orchestration and testpmd users, how about keeping both solution together? This will bring max flexibility IMHO.

As I said before I don't mind and I really think it is a good
idea to add suggested interface to specify representor
(i.e. cXpfYvfZ), but the problem is making bitmap from
representor ID.

ethdev API should use new representor info API to
make a representor ID from controller/PF/{VF,SF}.
Or do you see any problems with such approach?

> In struct rte_eth_dev_data, reserved bits could be used to define controller and port, this will avoid bitmap. How do you think?

Could you add a bit more on it? Just a bit more details to
the idea since I don't understand what exactly you mean and
how it could help.

>>
>> There is one more bit which is not in the picture yet - switch_info.port_id. Should it be equal to representor ID? Or different and
>> provided in the info structure?
> 
> Not exactly same AFAIK, the id used in e-switch.
> 
>