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Re: toolchain/47503: Request automated addition of gfortran to base compiler set

On 2/5/13 7:20 AM, Valeriy E. Ushakov wrote:
The following reply was made to PR toolchain/47503; it has been noted by GNATS.

From: "Valeriy E. Ushakov"<>
Subject: Re: toolchain/47503: Request automated addition of gfortran to base 
compiler set
Date: Tue, 5 Feb 2013 17:18:38 +0400

  On Mon, Feb 04, 2013 at 22:55:08 +0000, Jason Bacon wrote:

  >   RHEL and CentOS already include gfortran in the base, so a GCC package
  >   is unnecessary here.

  Does a typical Linux distribution even have a "base" in the same sense
  we speak about base system in BSDs?  My impression from my limited
  exposure is that in NetBSD terms their "base" gcc is what we would
  call a gcc package.
Not exactly. RHEL/CentOS don't necessarily have any development tools out of the box, but a Yum package in the 'base' category installs them into /usr/bin. This would be the first and usually only compiler suite on the system, so it's akin to the BSD base compilers.

The development tools "group" (like a metapackage) is what most people use. It installs all
the compilers, flex, bison, subversion, etc.

  >   We could get by with a GCC package on NetBSD, but since GCC 4.5 is now
  >   being used as the base compiler, and pkgsrc already contains the logic
  >   to use a base gfortran if it's present, I think it would make sense to
  >   have gfortran in the base (at least as an option).  This would ensure
  >   object code compatibility with code compiled by the base gcc and g++ as
  >   well.

  Are there some known ABI issues between recent 4.x series, or is it
  more in the bad vibes area? (I use it as a neutral technical (sic!:)
  term here)
I'm not aware of any issues between recent 4.x compilers, but that does not make me confident that they don't exist. I'll be more worried with GCC 5.0 becomes the preferred

  >   I think it would take fewer man-hours in the long run to put it
  >   in the base, and the end result would be cleaner and safer.

  ... for as long as gfortran in gcc 4.5 is considered ok, until some
  horrible bug that triggers only under rare conditions makes it
  unsuitable because you can't trust it any more.

  ... or when gcc 4.N+1 has optimizer improvements that cut you batch
  wall time by days and you absolutely want to use 4.N+1 instead of that
  old base 4.5

  ... or until we decide to upgrade the base compiler to, say, gcc 4.7
  and it turns out newer gfortran have issues.

  I'm sure pkgsrc folks can continute the list.

  From the base system persepective I'd say it would take fewer
  man-hours in the long run to make sure gfortran packages work smoothly.

  . de facto, optional code tends to bit-root

  . de jure, once in base, optional code is, effectively, mandatory

  . it's "mandatory optional" on *all* ports, including those no-one
    would ever going to use for HPC (vax heyday is over; jornada 680

  . it will have to be in the standard builds, so limited resources of
    netbsd autobuid cluster will be spent on building it (for all
This is why I initially suggested only providing instructions or a script for rebuilding the base compiler suite with gfortran enabled, rather than including it in the generic installation. Based on my experience with manual GCC builds, once you get the build working, adding
Fortran is unlikely to cause many issues.

  . we will have to solve *exactly the same* ABI compatibility issues
    (if any) during base gcc upgrade as pkgsrc needs to solve for a gcc
The ABI issues I'm worried about stem from the fact that the GCC package chosen as a prerequisite might be a different version than the base compilers and might be built with different options. Rebuilding the base suite guarantees the same
version, --build, --host, --target, etc.

  So the last item is the same for base and pkgsrc and all previous
  items are extra work for base.

  It's most likely that my perception of this problem is affected by my
  wearing base-hacker hat (mine might have -5 penalty to wisdom and
  cursed), so, please, excuse me if this mail might come across as a bit
  antagonistic - it's not inteded that way.


No worries. I see this as collaborative discourse, not a flame war. The least that can come of it is we all end up with a better understanding of the issues.

I won't be offended if the developers doesn't agree with my suggestions.  I
just want to have a discussion to raise awareness of the issues, and
offer some ideas for solving them.


Jason W. Bacon

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