2016-03-08 08:36, Dumitrescu, Cristian: > From: Thomas Monjalon [mailto:thomas.monjalon at 6wind.com] > > If this struct is used in a table, changing its size will break the ABI. > > This structure is already present in the API of the source port in file > librte_port/rte_port_source_sink.h, this patch is simply adding two new > fields at the end of it. I think we accepted adding parameters at the end of > the API parameter structures in other parts of DPDK without considering them > ABI breakages?
It depends of the struct but generally it is considered an ABI break. > Per Panu's previous comment, this structure is indeed used within an array of > unions in the ip_pipeline application, but (1) it is very unlikely a > "regular" user application will use it this same way; and (2) somebody using > the ip_pipeline application will upgrade both the library and the application > at the same time. > > If you guys still think this is breaking the ABI, please let us know asap and > we'll go with your suggestion. Yes it is. > > More generally, are you sure of the benefits of exposing a configuration > > structure in the API? > > This is not an internal (implementation side) structure, it is the external > (API side) structure with the parameters required from the user for creating > this object, I am not sure I understand your comment? There are 2 ways of passing parameters: struct or individual params. By using some functions with individual params, you can avoid ABI break (see librte_compat). In this case you would have a function pcap_config(). Just an idea.
