Re: [PATCH] MIPS: Allow R6 compact branch policy to be left unspecified

[Maciej W. Rozycki]

On Wed, 11 May 2016, Ralf Baechle wrote:

> I was wondering if we should simply probe for the availability of the
> GCC option and not use it, if using an older GCC, then change the
> help text for the option accordingly.  This approach would allow
> make randconfig or similar to work as expected with older compilers.

 Well, if the default is `optimal' anyway, then I think we can simply omit 
the option unless someone has requested an override.  In which case I 
think the compilation should fail if the option is not supported, under 
the principle of the least surprise -- if someone has requested a feature, 
then they ought to be informed that it is absent rather than silently 
fooled into thinking it has been enabled while in fact it has not.

 I agree probing for the presence of the option requested and then failing 
gracefully (e.g. "Toolchain feature FOO not available, please upgrade or 
reconfigure without BAR" or suchlike) is a better idea than just aborting 
midway through, and I think `randconfig' and similar validators should be 
prepared for it and handle gracefully as well (i.e. not a kernel bug).

 FWIW,

  Maciej