Re: Problems building FreeBSD 9.2 on FreeBSD 10

Trimmed CC a bit.

On Mon, Jun 23, 2014 at 11:42:20PM -0600, Warner Losh wrote:
> On Jun 23, 2014, at 8:24 PM, Glen Barber <gjb_at_freebsd.org> wrote:
> > I sort of typed what I meant a bit backwards from what I intended to
> > write.  What I meant (sort of) is, "I would like to discuss our forward
> > thinking on backward-compatibility."
> > 
> > I fully understand forward-compatibility is not feasible.
> 
> We already build current back to the stable/8 branch. 7.x is no longer feasible, supported or tested. stable/10 is the only one that is required, but enough people use stable/9 machines it will work. stable/8 has one customer that is keeping it going, so I suspect it will stop working in the coming years, maybe before 11 is branched.
> 

To be clear, I am talking about the other direction.  Meaning, being
able to "reliably" build N-2 from head/, without needing to do silliness
like 'make make buildworld', or "not using -jN."

> > I hate to even suggest this, but the ports tree (ab)uses the notion of
> > using the kern.osreldate for certain things.  This, however, requires
> > proper bumping of __FreeBSD_version when needed, and maintenance of the
> > Makefiles for the kern.osreldate-specific things.
> 
> We already do that. It mostly works most of the time, so long as the delta isn’t too great, and we don’t have high compiler/tools/make velocity… Except we don’t use the kernel version, but rather the installed tools version as indicated by a .h file. That’s more robust.
> 

True.  Thank you for the sanity check.

> > The benefit to this is that it would help prevent pissing off ports
> > developers and make their lives a bit easier when userland / kernel
> > things change.  It would, however, (expectedly) is that it would force
> > src committers to do the right thing.  Win-win, IMHO.
> 
> What should we do we aren’t doing today?
> 

There have been a number of times where changes that should deem
a __FreeBSD_version bump necessary either 1) do not bump
__FreeBSD_version at all, or 2) bump __FreeBSD_version several days (or
longer) later.  So, we're left with a window of time where something is
"different enough", but there is no corresponding version change to
reference.

This is somewhat tangential to my original annoyance here though. :)

> > Personally, and no I won't discuss more on this, I'm in the camp of "I
> > don't really see clang as a feature."  It caused our ports developers
> > and maintainers a mountain of headache to convert to the "invisibly new
> > great thing", it increases our overall buildworld by a non-insignificant
> > amount of time, and it has personally caused me headaches (still
> > ongoing) trying to figure out what the correct incantation of evil to
> > wish over the cauldron to get BeagleBone images to build.  (They're
> > failing because gcc is not being installed on both head/ and stable/10/,
> > and despite the game of "musical KNOBS" I've been playing over the past
> > few days, I'm running out of hair to pull out of my head.)
> 
> Yea, if you are using crochet, that’s because crochet uses xdev rather than a ports compiler (which in all fairness didn’t exist when it started) to build u-boot, which basically requires gcc.
> 
> The compiler rework in head is still a work in progress. What’s there now is better than before, but still isn’t quite right. I do plan on fixing that before summer is out.
> 

It isn't just head that is a problem with crochet, though.  stable/10
has been a problem since, as far as I can tell, roughly early May.

> >> But 9.2 will never build on head because it is broken with bmake, which is now standard for head. Since 9.2 cannot be changed, and since we’ve removed (or nearly) fmake in current, chances are quite good it will never build on head again without some special handling.
> >> 
> >> In summary, good luck! there’s a lot of use cases here, and it will take time and effort of multiple people over the long haul to keep it working. Best effort may be larger than you estimate… I won’t stand in your way, but I’m afraid my time available to help is limited.
> >> 
> > 
> > As Ozzy once sang:
> > 
> >    "I'm just a dreamer
> >    I dream my life away
> >    I'm just a dreamer
> >    Who dreams of better days”
> 
> Since I was commenting on the opposite problem of what you were wanting comments on, my harshness is justified.
> 

My comment wasn't a comment on your comment. :-)

> What you want though, we largely already do, though maybe with a few more warts than necessary (which we should try to fix). Most of the warts are due to gcc/clang division being done badly and unsustainable initially and the cleanup taking a bit of time, not specific version issues.
> 
> Back to your basic point, the issue becomes a testability one: not all committers can reasonable be expected to have 8 or 9 systems to test every change. Having a 10.x system to test changes is a bit of a stretch as it is, but it is the official policy that many folks play fast and loose with the rules because they haven’t been burned too often by it… VMs, Jails, etc of various flavors can help, but some info does leak through (mostly the info leaks are bugs or kludges that well meaning people shouldn’t have done given the historical knowledge we have about the ill effects of certain ways to do conditional compilation).
> 

To be fair, we do have reference machines in the cluster running head/,
stable/10, and stable/9.

Glen