Re: [dpdk-dev] [PATCH v6 4/4] docs: Add ABI documentation

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

2015-01-21 09:59, Neil Horman:
> On Wed, Jan 21, 2015 at 11:25:48AM +0100, Thomas Monjalon wrote:
> > 2015-01-20 16:17, Neil Horman:
> > > Adding a document describing rudimentary ABI policy and adding notice space for
> > > any deprecation announcements
> > > 
> > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> > > CC: Thomas Monjalon <thomas.monjalon@6wind.com>
> > > CC: "Richardson, Bruce" <bruce.richardson@intel.com>
> > > 
> > > ---
> > > Change notes:
> > > 
> > > v5) Updated documentation to add notes from Thomas M.
> > > 
> > > v6) Moved abi.txt to guides/rel_notes/abi.rst
> > 
> > You didn't integrate this file in the index.
> > 
> Shiobahn indicated that its just a plain text file, so I left it as a plain text
> file.  I guess we have different definitions of plain text files.
> 
> > [...]
> > 
> > > --- /dev/null
> > > +++ b/doc/guides/rel_notes/abi.rst
> > > @@ -0,0 +1,38 @@
> > > +ABI policy
> > > +==========
> > > +	ABI versions are set at the time of major release labeling, and ABI may
> > > +change multiple times between the last labeling and the HEAD label of the git
> > > +tree without warning
> > > +
> > > +	ABI versions, once released are available until such time as their
> > > +deprecation has been noted here for at least one major release cycle, after it
> > > +has been tagged.  E.g. the ABI for DPDK 1.8 is shipped, and then the decision to
> > > +remove it is made during the development of DPDK 1.9.  The decision will be
> > > +recorded here, shipped with the DPDK 1.9 release, and actually removed when DPDK
> > > +1.10 ships.
> > 
> > As previously said, speaking about 2.0/2.1 would be more coherent.
> > 
> As previously mentioned, I really don't see this as relevant, as it will be out
> of date within a release, and I think we can agree, no one is going to update
> this paragraph every release.
> 
> > > +
> > > +	ABI versions may be deprecated in whole, or in part as needed by a given
> > > +update.
> > > +
> > > +	Some ABI changes may be too significant to reasonably maintain multiple
> > > +versions of.  In those events ABI's may be updated without backward
> > > +compatibility provided.  The requirements for doing so are:
> > > +	1) At least 3 acknoweldgements of the need on the dpdk.org
> > > +	2) A full deprecation cycle must be made to offer downstream consumers
> > > +sufficient warning of the change.  E.g. if dpdk 2.0 is under development when
> > > +the change is proposed, a deprecation notice must be added to this file, and
> > > +released with dpdk 2.0.  Then the change may be incorporated for dpdk 2.1
> > > +	3) The LIBABIVER variable in the makefilei(s) where the ABI changes are
> > > +incorporated must be incremented in parallel with the ABI changes themselves
> > > +
> > > +	Note that the above process for ABI deprecation should not be undertaken
> > > +lightly.  ABI stability is extreemely important for downstream consumers of the
> > > +DPDK, especially when distributed in shared object form.  Every effort should be
> > > +made to preserve ABI whenever possible.  For instance, reorganizing public
> > > +structure field for astetic or readability purposes should be avoided as it will
> > > +cause ABI breakage.  Only significant (e.g. performance) reasons should be seen
> > > +as cause to alter ABI.
> > 
> > When applying the patch, there are these (minor) warnings:
> > 
> > /home/thomas/projects/dpdk/dpdk/.git/rebase-apply/patch:52: trailing whitespace.
> > /home/thomas/projects/dpdk/dpdk/.git/rebase-apply/patch:55: new blank line at EOF.
> > 
> > When building the documentation, there are these errors:
> > make doc-guides-html
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:4: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:8: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:15: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:18: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:20: ERROR: Unexpected indentation.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:22: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:25: ERROR: Unexpected indentation.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:26: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:29: WARNING: Block quote ends without a blank line; unexpected unindent.
> > /home/thomas/projects/dpdk/dpdk/doc/guides/rel_notes/abi.rst:: WARNING: document isn't included in any toctree
> > 
> > Please check it.
> > 
> Again, I guess we have separate definitions of what a plain text file is, but
> I'll look into it.
> 
> 
> > Other comment, what about the additions I suggested about macros and structure renaming?
> > 
> Considered and answered already.  I'm in favor of listing macros and structure
> changes in the abi document, but I think an exhaustive list isn't needed.  If it
> is, we could spend pages diving into minute.  Better to point out the need for
> abi noticies as patches get posted.

I'm afraid you don't understand what I'm saying. Copy/paste:
"No, I was suggesting to explain in this doc that macro removal must be
announced with a deprecation notice,
and that in case structure must be reworked, the name must change if we
want to preserve ABI compatibility with old structure."
Rewording: if you agree with this policy, please add it in this document.

> > Neil, we expect that you consider comments done previously and that you test your patch.
> > Otherwise, we are losing time in useless reviews.
> > 
> Thomas, I have considered your comments, I simply don't agree with all of them,
> and I made that clear.
> 
> As for losing time, you let the first attempt at this
> patch rot on the list in 1.7 and have done the same thing for the 1.8 cycle
> until I yelled for reviews.

Now, I'm really upset of your wrong assumptions.
You sent your first proposal on september, during 1.8 cycle, not 1.7 !
And during this cycle, the decision was to postpone it for 2.0 release.

I don't understand what's wrong with you.
You don't make any effort to understand what we are saying and
you make no effort to understand what is this doc directory.
You prefer crying that your patch is not applied.
And I still don't understand if you are willing to work on a test tool for ABI?

> No doubt when all is said and done here you'll
> complain because this series likely won't work when you apply it for all the
> patches you take between the time I posted it and now.  So lets be careful about
> complaining over wasted time.

Note that I'm sure we can do some good work together. And I'd prefer more
pleasant discussions. Life is too short to have this kind of conflict.

-- 
Thomas