Re: [dpdk-dev] RFC: DPDK Long Term Support

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-06-05 14:15, Neil Horman:
> On Fri, Jun 03, 2016 at 03:07:49PM +0000, Mcnamara, John wrote:
> > Introduction
> > ------------
> > 
> > This document sets out a proposal for a DPDK Long Term Support release (LTS).
> > 
> > The purpose of the DPDK LTS will be to maintain a stable release of DPDK with
> > backported bug fixes over an extended period of time. This will provide
> > downstream consumers of DPDK with a stable target on which to base
> > applications or packages.
[...]
> I'm not opposed to an LTS release, but it seems to be re-solving the issue of
> ABI breakage.  That is to say, there is alreay a process in place for managing
> ABI changes to the DPDK, which is designed to help ensure that:
> 
> 1) ABI changes are signaled at least 2 releases early
> 2) ABI changes whenever possible are designed such that backward compatibility
> versions can be encoded at the same time with versioning tags

Sorry I don't understand your point.
We are talking about two different things:
1/ ABI care for each new major release
2/ Minor release for bug fixes

I think both may exist.

> Those two mechanism are expressly intended to allow application upgrades of DPDK
> libraries without worrying about ABI breakage.  While LTS releases are a fine
> approach for  some things, they sacrifice upstream efficiency (by creating work
> for backporting teams), while allowing upstream developers more leverage to just
> create ABI breaking changes on a whim, ignoring the existing ABI compatibility
> mechanism

No it was not stated that upstream developers should ignore ABI compatibility.
Do you mean having a stable branch means ABI preservation for the next major
release is less important?

> LTS is a fine process for projects in which API/ABI breakage is either uncommon
> or fairly isolated, but that in my mind doesn't really describe DPDK.

Yes API/ABI breakages are still common in DPDK.
So it's even more important to have some stable branches.