Consensus: Tuning runtime behaviour with environment variables.

[Rich Felker]

On Wed, May 29, 2013 at 12:56:50AM -0400, Carlos O'Donell wrote:
> Community,
> 
> I'd like to drive some consensus around the idea of using
> environment variables to tune runtime behaviour in glibc.

Like Roland, I'm largely opposed to environment variables or any means
of tuning the library behavior for an already-built/installed
application. However, if the community deems them desirable, my hope
would be that, at the very least:

- Aside from a few existing grandfathered-in ones, environment
  variables or other tunables should merely transform the library from
  one conforming implementation to a different conforming
  implementation. No settings should make it non-conforming.

- Any settings which could cause a conforming application which works
  correctly with the default settings to stop working correctly should
  be ignored completely when the program is suid or AT_SECURE is set
  in the aux vector.

- The namespace for glibc tuning variables should be clearly defined
  in such a way that they can be mechanically removed from the
  environment without having to worry that future additions will be
  missed by the stripping code.

Rich