Re: [dpdk-dev] How to replace rte_eth_dev_attach with rte_eal_hotplug_add

["Gaëtan Rivet" <gaetan.rivet@6wind.com>]

On Thu, Sep 20, 2018 at 05:46:37PM +0900, Hideyuki Yamashita wrote:
> Hello,
> 
> From dpdk 18.08 release rte_eth_dev_attach and 
> rte_eth_dev_detach becom deprecated API and 
> it is recommended to replace with rte_eal_hotplug_add
> and rte_eal_hotplug_remove.
> 
> My program uses  above mentioned deprecated APIs
> and have to replace those.
> Note that my program uses attach to attach vhost, pcap pmd.
> 
> My question is whether it is correct to replace those as following:
> find rte_eth_dev_attach function in rte_ethdev.c and
> migrate those content into my program.
> 
> e.g. 
> lib/librte_ethdev/rte_ethdev.c line 643-686 for attach
> lib/librte_ethdev/rte_ethdev.c line 690-720 for detach
> 
> Your advice/guidance are much appreciated.
> Thanks!
> 
> BR,
> Hideyuki Yamashita
> -----------------------------------------
> Hideyuki Yamashita
> NTT TechnoCross
> -----------------------------------------
> 
> 

Hello Hideyuki,

You could use this code for guidance, while leaving the ethdev
specificities such as verifying the eth_dev_count_total(). The hotplug
function would already return an error if the PMD was not able to create
the necessary devices.

The main issue might be to find the port_id of your new port.
You won't be able to use eth_dev_last_created_port, so you would have to
iterate over the ethdev using RTE_ETH_FOREACH_DEV and find the one
matching your parameters (you might for example match the rte_device
name with the name you used in hotplug_add, as there is no standard
naming scheme at the ethdev level).

An possible issue with the deprecation planned for those two functions is
that the hotplug API is also meant to evolve [1] this release (not in a big
way however, it would mostly simplify your usage of it).

[1]: https://mails.dpdk.org/archives/dev/2018-September/111142.html

Best,
-- 
Gaëtan Rivet
6WIND