[dpdk-dev] Clarification for eth_driver changes

[Jianbo Liu]

Hi Thomas,

On 10 November 2016 at 16:58, Thomas Monjalon <thomas.monjalon at 6wind.com> wrote:
> 2016-11-10 14:12, Shreyansh Jain:
>> On Thursday 10 November 2016 01:33 PM, Thomas Monjalon wrote:
>> > 2016-11-10 15:51, Jianbo Liu:
>> >> On 10 November 2016 at 15:26, Shreyansh Jain <shreyansh.jain at nxp.com> wrote:
>> >>> This is what the current outline of eth_driver is:
>> >>>
>> >>> +------------------------+
>> >>> | eth_driver             |
>> >>> | +---------------------+|
>> >>> | | rte_pci_driver      ||
>> >>> | | +------------------+||
>> >>> | | | rte_driver       |||
>> >>> | | |  name[]          |||
>> >>> | | |  ...             |||
>> >>> | | +------------------+||
>> >>> | |  .probe             ||
>> >>> | |  .remove            ||
>> >>> | |  ...                ||
>> >>> | +---------------------+|
>> >>> |  .eth_dev_init         |
>> >>> |  .eth_dev_uninit       |
>> >>> +------------------------+
>> >>>
>> >>> This is what I was thinking:
>> >>>
>> >>> +---------------------+        +----------------------+
>> >>> | rte_pci_driver      |        |eth_driver            |
>> >>> | +------------------+|       _|_struct rte_driver *p |
>> >>> | | rte_driver       <-------/ | .eth_dev_init        |
>> >>> | |  ...             ||        | .eth_dev_uninit      |
>> >>> | |  name            ||        +----------------------+
>> >>> | |  <more>          ||
>> >>> | +------------------+|
>> >>> |  <PCI specific info>|
>> >>> +---------------------+
>> >>>
>> >>> ::Impact::
>> >>> Various drivers use the rte_pci_driver embedded in the eth_driver object for
>> >>> device initialization.
>> >>>  == They assume that rte_pci_driver is directly embedded and hence simply
>> >>> dereference.
>> >>>  == e.g. eth_igb_dev_init() in drivers/net/e1000/igb_ethdev.c file
>> >>>
>> >>> With the above change, such drivers would have to access rte_driver and then
>> >>> perform container_of to obtain their respective rte_xxx_driver.
>> >>>  == this would be useful in case there is a non-PCI driver
>> >>>
>> >>> ::Problem::
>> >>> I am not sure of reason as to why eth_driver embedded rte_pci_driver in
>> >>> first place - other than a convenient way to define it before PCI driver
>> >>> registration.
>> >>>
>> >>> As all the existing PMDs are impacted - am I missing something here in
>> >>> making the above change?
>> >>>
>> >>
>> >> How do you know eth_driver->p is pointing to a rte_pci_driver or rte_soc_driver?
>> >> Maybe you need to add a type/flag in rte_driver.
>> >
>> > Why do you need any bus information at ethdev level?
>>
>> AFAIK, we don't need it. Above text is not stating anything on that
>> grounds either, I think. Isn't it?
>
> No, I was replying to Jianbo.
> Anyway, David made a more interesting comment.

Indeed, no need as I checked the code.
It's not even a issue if using David's design.

Thanks!
Jianbo