Re: git: e2650af157bc - main - Make CPU_SET macros compliant with other implementations

On Fri, Dec 31, 2021 at 11:34:34AM -0700, Warner Losh wrote:
> On Fri, Dec 31, 2021 at 11:29 AM Konstantin Belousov <kostikbel@gmail.com>
> wrote:
> 
> > On Fri, Dec 31, 2021 at 01:08:25PM -0500, Ed Maste wrote:
> > > Some time ago I started a best practises doc for potentially
> > > disruptive src changes (and have received some feedback, including
> > > from folks on this thread). I'll paste it here for further discussion.
> > > ---
> > > This is the suggested process for introducing tool chain and other
> > > changes in the src tree that may cause significant disruption to
> > > ports. Some examples of potentially disruptive changes are:
> > >
> > > - major compiler updates
> > > - OpenSSL updates
> > > - adding a library or system call (such as memfd) that is already
> > > present on other systems
> > > - changing the semantics or APIs of existing libraries
> > >
> > > The goal of this document is not to be overly prescriptive, but to
> > > document a process that has produced good results in the past, avoid
> > > surprises among ports committers and maintainers, and clarify the
> > > expectation on port maintainers to collaborate on addressing fallout
> > > from the potentially disruptive change. The project gets the best
> > > results when everybody works together, in good faith, to solve
> > > problems with disruptive changes.
> > >
> > > Disruptive change process:
> > >
> > > 1. Request a ports exp-run with the desired change. This is used to
> > > determine the initial impact of the change. If the exp-run shows no
> > > impact or minimal impact the rest of the process may be skipped.
> > >
> > > 2. Verify that important packages build, and fix identified failures.
> > > Maintainers of important packages should be prepared to assist.
> > > Important (critical?) packages include:
> > >
> > > - pkg
> > > - binutils
> > > - gcc
> > > … (need to expand this list)
> > >
> > > 3. Post a Heads-Up email to at least the FreeBSD-current and
> > > FreeBSD-ports mailing lists with a proposed schedule. Where
> > > appropriate add other mailing lists, such as FreeBSD-toolchain. Allow
> > > at least three weeks between the Heads-Up email and the commit.
> > >
> > > 4. In the period between the Heads-Up email and the commit, developers
> > > proposing the change and maintainers of ports affected by the change
> > > work together to resolve any ports failures.
> > And what to do if developers are not 'collaborative'?  For my case, there
> > was a silence from ports maintainers, even after
> > - a tool was proposed
> > - a request for feedback was issued
> >
> 
> There's a timeout in ports. If the maintainer is unresponsive, you can
> proceed.
> There's some tweaking we can do to the timeouts, to be sure, but I've had
> several
> things time out and I was good to proceed with my changes.
Timeouts in ports are only for maintainer approval of ports changes.
If you need somebody to (help) develop the changes, timeout does not
provide any support.

> 
> For base changes in ABI, maybe we need a faster expectation for feedback as
> well as allowing breakage when the timeout is reached and there aren't some
> compelling reasons not to proceed.
[We do not allow ABI changes at all, except additions of interfaces FWIW]

> 
> 
> > >
> > > 5. Request additional exp-runs as necessary (by adding a comment in
> > > the existing PR).
> > >
> > > 6. Commit may proceed once all important/critcal ports build, and either:
> > >
> > > - The deadline proposed in the Heads-Up email has been reached
> > > - There is a concensus that remaining failures are insignificant (for
> > > example, a small number of unmaintained leaf ports are the only
> > > outstanding failures)
> > >
> > > 7. Collaborate on fixing any outstanding issues (e.g. broken leaf ports)
> >
> > This is good wishes, at best. This assessment is backed by my experience
> > both with ino64, and with sched_get/setaffinity. Either source changes
> > are blocked indefinitely, or source committer is tasked with fixing all
> > broken ports.
> >
> 
> It's never that absolute: I've made changes I knew would break ports that
> were deemed to be unsupported enough to just mark broken. But having a list
> of things that might be broken allowed me to work with portmgr to make this
> call.

In this case, I did not expected that addition of two functions would
break anything. Apparently it did, because autoconf software checked
linkage with them, ignoring availability of prototype. And after the
functions presence was detected, software assumed that whole set of
glibc-compatible API of CPU_XXX is there.

Requesting exp-runs for addition of each exported function is not
constructive.