[dpdk-dev] Clarification for eth_driver changes

[Shreyansh Jain <shreyansh.jain@nxp.com>]

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?

Probably, similar is the case for rte_eth_dev.

-
Shreyansh