Re: [dpdk-dev] Clarification for eth_driver changes

[Jianbo Liu <jianbo.liu@linaro.org>]

On 10 November 2016 at 15:26, Shreyansh Jain <shreyansh.jain@nxp.com> wrote:
> Hello David, list,
>
> I need some help and clarification regarding some changes I am doing to
> cleanup the EAL code.
>
> There are some changes which should be done for eth_driver/rte_eth_device
> structures:
>
> 1. most obvious, eth_driver should be renamed to rte_eth_driver.
> 2. eth_driver currently has rte_pci_driver embedded in it
>  - there can be ethernet devices which are _not_ PCI
>  - in which case, this structure should be removed.
> 3. Similarly, rte_eth_dev has rte_pci_device which should be replaced with
> rte_device.
>
> 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.

> Probably, similar is the case for rte_eth_dev.
>
> -
> Shreyansh