Re: [PATCH] Cleanup MIPS preconfigure script

[Steve Ellcey <sellcey at mips dot com>]

On Thu, 2014-09-04 at 23:29 +0100, Maciej W. Rozycki wrote:

>  Hmm, that's quite a change in the interpretation of host triplets, but 
> I'm leaning towards finding it acceptable, I think we have sufficient 
> means in GCC nowadays to control the default ABI so that we don't have to 
> rely on suffixes in the triplets.  I wonder if a sanity check wouldn't be 
> good to have though, such as rejecting mips64* with the compiler set to 
> the 32-bit ABI to trap accidental silly use.

Someone might want to use a 32 bit ABI on mips64 though, how about a
warning instead of an error for that case?

>  Your change has a flaw though, you can't rely on _MIPS_ISA being set 
> exactly to _MIPS_ISA_MIPS64 on determining if you want a 64-bit or a 
> 32-bit configuration, there are other 64-bit ISAs, starting from 
> _MIPS_ISA_MIPS3, e.g. I have an n64 MIPS III compiler.  I think you can 
> just skip this check altogether, GCC will have set the ABI and the ISA 
> consistently already and you can merge the two legs of this conditional 
> into one.  You may just sanity-check that a 64-bit ABI is not used 
> together with the MIPS16 option as we have no 64-bit MIPS16 PIC support.

I like the idea of not using _MIPS_ISA.  The other difference between
the 32 and 64 branches is setting 'base_machine' and it doesn't look to
me that we use base_machine anywhere.  The only use of it anywhere in
glibc that I see is in the x86_64 preconfigure script.  I agree that
using mips16 with n32 or n64 should be an error.  I will update the
patch.

Steve Ellcey