Re: [dpdk-dev] [RFC v2] meter: fix ABI break due to experimental tag removal

From: Luca Boccassi <bluca@debian.org>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: Ferruh Yigit <ferruh.yigit@intel.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	 Cristian Dumitrescu <cristian.dumitrescu@intel.com>,
	Eelco Chaudron <echaudro@redhat.com>,
	dev@dpdk.org, David Marchand <david.marchand@redhat.com>,
	Bruce Richardson <bruce.richardson@intel.com>,
	 Ian Stokes <ian.stokes@intel.com>,
	Andrzej Ostruszka <amo@semihalf.com>
Subject: Re: [dpdk-dev] [RFC v2] meter: fix ABI break due to experimental tag removal
Date: Thu, 30 Jan 2020 16:04:47 +0000	[thread overview]
Message-ID: <3a08271e0d811359f7dc1cc732b6bdc89cc98a4e.camel@debian.org> (raw)
In-Reply-To: <5634584.alqRGMn8q6@xps>

On Thu, 2020-01-30 at 16:55 +0100, Thomas Monjalon wrote:
> 30/01/2020 15:21, Luca Boccassi:
> > On Thu, 2020-01-30 at 15:17 +0100, Thomas Monjalon wrote:
> > > 30/01/2020 13:57, Luca Boccassi:
> > > > On Thu, 2020-01-30 at 13:33 +0100, Thomas Monjalon wrote:
> > > > > Hi,
> > > > > 
> > > > > I disagree with the need of this patch.
> > > > > The symbol was experimental, meaning we can change it.
> > > > > Removing experimental tag is not an ABI break.
> > > > 
> > > > Hi,
> > > > 
> > > > This symbol change was requested for backport in 19.11.x, and
> > > > experimental or not I'm not too keen on backward incompatible
> > > > changes
> > > > to the public interface in an _LTS point release_. The
> > > > compromise
> > > > was
> > > > to see if we could support both symbols version, which makes
> > > > the
> > > > change
> > > > backward compatible.
> > > > 
> > > > If you prefer not to have this patch in mainline I'm also fine
> > > > in
> > > > taking it just for the LTS. I agree with you that it is not
> > > > required
> > > > for mainline releases (although nicer for me if it's a backport
> > > > rather
> > > > than a new change).
> > > 
> > > I would like to avoid opening the door for maintaining the
> > > experimental ABI
> > > in the mainline. Please take it directly in the LTS.
> > > 
> > > The next question is to know whether we really want to have such
> > > patch in LTS.
> > > Anyway, 19.11.0 has this symbol as experimental.
> > > How adding a non-experimental version of the function in 19.11.1
> > > will
> > > change
> > > the ABI status of the whole 19.11 branch?
> > 
> > The problem is not adding the new symbol, but removing the
> > experimental
> > one. Changing the version of the symbol was requested by OVS for
> > inclusion in 19.11.
> 
> Yes, sorry, this is what I meant.
> Given 19.11.0 already has the symbol as experimental,
> and that applications like OVS had to accept it as experimental,
> why removing experimental tag in 19.11.1?

I think it was mentioned that it was preferred not to suppress the
compiler warning to avoid any accidental use in the future, but the OVS
maintainer(s) should answer as I might remember wrongly.

-- 
Kind regards,
Luca Boccassi